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Friday, August 31, 2012

Grid Compass Computer - Pioneering the Laptop

1986-GRiD Gridcase 1520 laptop

Video Link...

Pioneering the Laptop - The GRiD Compass

Video Link (1hr 30min)...

Man, these are Cool!:) They were used on the Space Shuttle too... I want one now!


GRiD Compass 1101
Released: 1982
Price: US$8150
Weight: 10 lbs, 12 oz
CPU: Intel 8086 @ 8MHz (?)
Display: 6-inch electroluminescent

80 x 24 text

320 x 240 graphics
Ports: RS-232/422 serial

GPIB parallel port
Storage: internal 384K bubble RAM

external floppy drive(s)

GRiD onboard Space Shuttle "Discovery"
mission STS-51G - June 1985.

Designed to be the ultimate portable computer, the clamshell-style GRiD Compass 1101 is the grand-daddy of all present-day laptop computers.

The Compass is very high-tech, with its flat-black, die-cast magnesium-alloy case, and bright, sharp electroluminescent display (ELD). No other system packed so much speed and power in as small a case, and none had such a unique and large, easy-to-read screen, allowing full 80x24 text.

Of course, all of these great features raised the price significantly. At $8150, the GRiD Compass 1101 was the most expensive personal computer you could buy.

Originally developed for business executives, GRiDs were also used by the U.S. military 'in the field', and by NASA on the Space Shuttles during the 1980's and 90's. It's even been said that the US President's "nuclear football" at one time included a GRiD computer.

Few, if any, non-IBM computers in 1982 ran MS-DOS, and the GRiD is no exception. Although MS-DOS compatibility was eventually added, the original GRiD 1101 ran only the GRiD-OS operating system - its design started in 1979, before MS-DOS or the IBM PC existed.

But GRiD-OS is no slouch - the suite includes:
-GRiDManager  -communication and utility functions
-GRiDPrint -control format and appearance of text files
-GRiDWrite -full-screen text editor
-GRiDPlan -electronic worksheets
-GRiDFile -database facilities
-GRiDPlot -converts data to graphs
-GRiDBASIC -programming language

Controlled almost entirely my menus, GRiD-OS is a full-function, powerful operating system. It displays data by DEVICE, SUBJECT (folder), TITLE (file name), and KIND (file type). Files can be password protected if desired.


Grid Compass

From Wikipedia, the free encyclopedia
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Astronaut John Creighton posing with a Grid Compass aboard a Space Shuttle Discovery mission in 1985. It displays Mr. Spock of Star Trek
Developer Bill Moggridge[1]
Type Portable computer
Release date April 1982
Introductory price 8150 USD [1]
Operating system Grid-OS
CPU Intel 8086
Memory 340 KB magnetic bubble[2]
Display 320 x 240
Connectivity 19-pin "serial", Telephone Line+Audio 1,200 bit/s modem, GPIB[2]
Successor GridCase 1535EXP[2]
The Grid Compass (written GRiD by its manufacturer GRiD Systems Corporation) was one of the first laptop computers when the initial model was introduced in April 1982 (the model 1101[3]).
The computer was designed by British industrial designer Bill Moggridge in 1979, and first sold three years later. The design used a clamshell case (where the screen folds flat to the rest of the computer when closed), which was made from a magnesium alloy. The computer featured an Intel 8086 processor, a 320 × 240-pixel electroluminescent display, 340-kilobyte magnetic bubble memory, and a 1,200 bit/s modem. Devices such as hard drives and floppy drives could be connected via the IEEE-488 I/O (also known as the GPIB or General Purpose Instrumentation Bus). This port made it possible to connect multiple devices to the addressable device bus. It weighed 5 kg (11 lb). The power input is ~110/220 V AC, 47–66 Hz, 75 W.
The Compass ran its own operating system, GRiD-OS. Its specialized software and high price (8–10,000 USD) meant that it was limited to specialized applications. The main buyer was the U.S. government. NASA used it on the Space Shuttle during the early 1980s, as it was both powerful and lightweight. The military Special Forces also purchased the machine, as it could be used by paratroopers in combat.
Along with the Gavilan SC and Sharp PC-5000 released the following year, the GRiD Compass established much of the basic design of subsequent laptop computers, although the laptop concept itself owed much to the Dynabook project developed at Xerox PARC from the late 1960s. The Compass company subsequently earned significant returns on its patent rights as its innovations became commonplace.
The portable Osborne 1 computer sold at around the same time as the GRiD, was more affordable and more popular, and ran the popular CP/M operating system. But, unlike the Compass, the Osborne was not a laptop and lacked the Compass's refinement and small size.
The Compass's manufacturer, Grid Systems Corp., was acquired by Tandy Corporation (RadioShack) in 1988.


  1. ^ a b "World's first laptop. Osborne 1 GRiD Compass 1101.". 090519
  2. ^ a b c "Daves old computers - PC compatibles". 090519
  3. ^ The model 1100 did not exist, except in marketing materials, the released machine was the model 1101. Pioneering the Laptop - The GRiD Compass

External links

Go there...

Grid Compass Computer - Pioneering the Laptop
Grid Compass - Wikipedia, the free encyclopedia
Grid Compass Computer - Google Search
Pioneering the Laptop - The GRiD Compass - YouTube
Grid Compass Computer - Google Search
Grid Compass - Wikipedia, the free encyclopedia
GRiD Compass 1101 computer
DigiBarn Systems: GRiD Compass II
Grid Compass Computer - Google Search
Uncle Roger's Computers -- GRiD Compass 1101
History of Computers and Computing, Birth of the modern computer, Personal computer, Grid Compass
Old Computers - rare, vintage, and obsolete computers
1986-GRiD Gridcase 1520 laptop - YouTube and Vitage Computer info
OLD-COMPUTERS.COM Museum ~ Tandy Radio Shack TRS 80 PC-2 software & screenshots
Space 1999: An isometric action adventure game for your Oric
The Official Blog of Benjamin J Heckendorn
Old computer ads
Old Computers - rare, vintage, and obsolete computers
Sharp PC-7000
Ohio Scientific Superboard II model 600 computer
IBM 5120 / IBM 5110 model 3 / IBM 5110-3 computer system
Processor Technology Sol-20 Terminal Computer
KIM-1 computer
MITS Altair 8800 computer
IMSAI 8080 computer
IBM 5100 computer
Apple 1 computer
Homebrew Computer Club - Wikipedia, the free encyclopedia
Pirates of Silicon Valley - Wikipedia, the free encyclopedia
Apple II computer
Tandy Radio Shack TRS-80 model I computer
Dinosaur Sightings: Computers from the 1970s | TechRepublic
Tandy/Radio Shack TRS-80 model III computer
TRS-80 - Wikipedia, the free encyclopedia
File:TRS-80 Model I - Rechnermuseum Cropped.jpg - Wikipedia, the free encyclopedia
Tandy Corporation - Wikipedia, the free encyclopedia
File:GRiDCompassInSpace.jpg - Wikipedia, the free encyclopedia
Osborne 1 - Wikipedia, the free encyclopedia
Dynabook - Wikipedia, the free encyclopedia
File:Alan Kay and the prototype of Dynabook, pt. 5 (3010032738).jpg - Wikipedia, the free encyclopedia
PARC (company) - Wikipedia, the free encyclopedia
Gavilan SC - Wikipedia, the free encyclopedia
Sharp PC-5000 - Wikipedia, the free encyclopedia
Altair 8800 - Wikipedia, the free encyclopedia
File:Altair 8800 Computer.jpg - Wikipedia, the free encyclopedia
The Internet in 1969 - YouTube
Old Laptop (1988) - YouTube
My Vintage Computer Collection - YouTube

Thursday, August 30, 2012

Radio Shack TRS-80 was Tandy Corporation's desktop microcomputer model line, sold through Tandy's Radio Shack stores in the late 1970s and early 1980s, and one of the earliest mass-produced personal computers

The Radio Shack TRS-80 Computer. Is the one that I let get away. Back in the Day... So now... I am interested in restoring one or maybe adding a new Mother Board to one of the old Systems to make it sort of a Hot Rod Vintage Computer. I almost bought a TRS-80 System, back in the day (early 80's). I can't remember which one I was looking at now. But, I had no experience with Computers and decided that it was a bit of an expensive Toy for me. I didn't end up learning how to use a Computer until 1992. It was a 486 with Windows 3.1 and it was connected to the Internet too!:) Then in 1996, when my health got bad and I couldn't do the same physical jobs, that I use to do. I really got into Computers (on a Packard Bell 486 with Win3.1). I went on through the years with Win98 and WinXP, learning about Windows and Viruses!:O Now, I have been working on and with Computers every day since 1998. I've been running Linux since 2005 as my main OS. And I love to put Linux on old PC's and make them useful again. I have some older Computers. That I experiment, learn and play with from time to time. From a 286, 386, 486, 75MHz P1's to 750MHz P3's. Then there's my TV - Video Watching P4 System. And my Every Day System (a 1.8GHz Core 2 Duo, my newest). I run Fedora 14 Linux, on them both. And they are both setup to Duel or Triple Boot Different OS's. I like Debian Linux allot too. And I still have WinXP on my P4, for those times when I want to run a Windows App. I've tried out at least 100 (lost track now) different Linux Distros over they years on CD -DVD or USB and in Virtual Machines (Virtual Box and Qemu VM's). I'm not a Programmer or a Electronics Engineer. I just like learning about Old and New Electronics. I sometimes wish that I had got into Computing much earlier. But, I might of tired of Computers by now too;) I live in Azle TX and that is about 12 miles from Fort Worth TX. Which was the Head Quarters of Tandy Corp, who owned Radio Shack, back when they made Computers. We actually had a Tandy Manufacturing Plant here in Azle, during the 80's. And I believe it stayed running until the early to mid 90's. So, the Radio Shack - Tandy Computers are of special interest to me. Below are some Videos on the TRS-80's and a bunch of info that I found on the History of Tandy - Radio Shack Computers. And there are plenty of links to more videos and info at the bottom of the page too...


TRS-80 Tandy Radio Shack Model 1

Video Link...


Video Link...

TRS-80 Model 1 vintage computer set up and boot up - part 1

Video Link...

TRS-80 Model 1 vintage computer set up and boot up - part 2

Video Link...

Tandy Color Computer - A Closer Look (TRS-80 CoCo)

Video Link...

Radio Shack TRS-80 Model III

Video Link...

Radio Shack TRS-80 Commercial 1979 1980

Video Link...

Radio Shack TRS-80 MC-10 Micro Color Computer review

Video Link...

Radio Shack TRS-80 Model III
Introduced: July 1980
Price: US $699 base model
US $2495 w/ 32K, dual drives.
CPU: Zilog Z-80, 2.03 MHz
RAM: 4K, 48K max.
Ports: Cassette tape, expansion, serial
Display: 12-inch B/W monitor: 64 X 16 text
Strorage: 0, 1, or 2 internal 178K floppy drives

External cassette @ 500 / 1500 baud
OS: BASIC in ROM, TRS-DOS on disk

The Model III is basically an upgrade of the Model I, which was released three years earlier. It has the same CPU, but it is faster, has more memory, and the floppy drives hold twice as much data, although the Model I could be upgraded to some of these features.


Radio Shack TRS-80
(Model I)
Catalog: 26-1001
Released: August 1977
Price: US $599.95 (with monitor)
How Many: 200,000 (1977-1981)
CPU: Zilog Z-80A, 1.77 MHz
RAM: 4K, 16K max*
Ports: Cassette I/O, video,

Expansion connector*
Display: 12-inch monochrome monitor

64 X 16 text
Expansion: External Expansion Interface*
Storage: Cassette storage*
* Additional capabilties with Expansion Interface

RS=Radio Shack
80=Z-80 microprocessor

Where's the computer? It's in the keyboard! As one of the first home computers ever, the TRS-80 was a great success. Tandy wasn't expecting many sales, but this, their first computer, sold 10,000 units in the first month alone. It includes everything you need to have a real computer of your very own - the computer, monitor and cassette deck for loading and saving data.

Yes, these were the days when you bought, loaded and saved your data and programs on cassette tapes.



From Wikipedia, the free encyclopedia
  (Redirected from Radio Shack TRS-80)
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TRS-80 Model I with Expansion Interface
Type Home computer
Release date August 3, 1977[1]
Discontinued January 1981
CPU Zilog Z80 @ 1.78 MHz
Memory 4 KB ~ 48 KB
TRS-80 was Tandy Corporation's desktop microcomputer model line, sold through Tandy's Radio Shack stores in the late 1970s and early 1980s, and one of the earliest mass-produced personal computers.[2] The first units, ordered unseen, were delivered in November 1977, and rolled out to the stores the third week of December. The line won popularity with hobbyists, home users, and small-businesses. Tandy Corporation's leading position in what Byte Magazine called the "1977 Trinity" (Apple, Commodore and Tandy) had much to do with Tandy's retailing the computer through more than 3,000 of its Radio Shack storefronts.[3] Notable features of the original TRS-80 included its full-stroke QWERTY keyboard, small size, its floating point BASIC programming language, an included monitor, and a starting price of $600.[1] The pre-release price was $500 and a $50 deposit was required, with a money back guarantee at time of delivery. One major drawback of the original system was the massive RF interference it caused in surrounding electronics. Stricter FCC regulations on interference led to the Model I's replacement by the Model III.[4]
By 1979, the TRS-80 had the largest available selection of software in the microcomputer market.[5]

The Model I


In the mid-1970s, Radio Shack was a successful American chain of electronics stores. After Don French, a buyer for the company, purchased a MITS Altair kit computer, he began designing his own and showed it to vice president of manufacturing John V. Roach. Although Roach was unimpressed, Radio Shack hired Steve Leininger from National Semiconductor to evaluate French's design, and they began working together in June 1976. The company envisioned a kit, but Leininger—who had worked at early computer store Byte Shop—persuaded the others that because "too many people can't solder", a preassembled computer would be better.[6][7]
Despite internal opposition to selling a microcomputer, as the popularity of CB radio—at one point more than 20% of Radio Shack's sales—declined, the company sought new products. In December 1976 French and Leininger received official approval for their project but were told to emphasize cost; for example, leaving out lowercase characters saved $1.50 in components and reduced the retail price by $5. In February 1977 they showed their prototype, running a simple tax-accounting program, to Charles Tandy, head of Radio Shack's parent Tandy Corporation. The program quickly crashed as the computer could not handle the $150,000 figure that Tandy typed in as his salary, and the two men added support for floating-point math to its Tiny BASIC to prevent a recurrence. French suggested that the company could sell 50,000 computers, but more skeptical executives disagreed and suggested 1,000 to 3,000 per year at the target $199 price. Roach persuaded Tandy to agree to build 3,500—the number of Radio Shack stores—so that each store could use a computer for inventory purposes if they did not sell.[6][7][8][5][9]
Radio Shack announced the TRS-80 (Tandy Radio Shack) at a New York City press conference on August 3, 1977. It cost $399, or $599 with a 12" monitor and a Radio Shack tape recorder as datacassette storage. Before this, the most expensive product Radio Shack sold was a $500 stereo. The company hoped that the new computer would help Radio Shack move into higher-priced products, and improve its "schlocky" image among customers. Small businesses were the primary target market, followed by education, then consumers and hobbyists. Despite its hobbyist customer base, Radio Shack saw hobbyists as "not the mainstream of the business". Although the press conference did not receive much media attention due to a terrorist bombing elsewhere in the city that day, "six sacks of mail" arrived at company headquarters asking about the computer, and over 15,000 people called Tandy to purchase a TRS-80, paralyzing its switchboard. Unlike competitor Commodore—which had announced its PET several months earlier but had not yet shipped any—Radio Shack began shipping computers by September. Still forecasting 3,000 sales a year, the company sold over 10,000 TRS-80s Model Is in its first one and a half months of sales, and over 200,000 during the product's lifetime.[6][10][7][8][5][11][9][12]:4[13]
Roach became Tandy's CEO in 1981, Leininger became its director of strategic planning, and French founded a software company. Although selling computers did not change Radio Shack's image and its executives disliked the "Trash-80" nickname for its products, by 1984 computers accounted for 35% of its sales, and the company had 500 Tandy Radio Shack Computer Centers.[6][8][11][14]


The Model I combined the mainboard and keyboard into one unit, in what was to be a common case design trend throughout the 8-bit microcomputer era, although it had a separate power supply unit. It used a Zilog Z80 processor clocked at 1.77 MHz (later models were shipped with a Z80A). The basic model originally shipped with 4 KB of RAM, and later 16 KB.[7]


The implementation of the keyboard was unusual. Instead of transferring data through an I/O chip, the hardware mapped the keyboard to dedicated locations in the processor's memory. Performing a read from the keyboard area of the memory would return the state of a particular set of keys.
A version of the computer was produced which replaced the nameplate with a numeric keypad.
Many users complained about the TRS-80 keyboards, which used mechanical switches and suffered from "Keyboard Bounce", resulting in multiple letters being typed accidentally.[15] A Keyboard De-Bounce tape was distributed, which altered the system's software to reduce the effect of bounce and to slow down polling of the keyboard. Eventually, this change was added to a later ROM revision. The keyboard hardware was also changed to be less vulnerable to bounce.


The TRS-80 was accompanied by a white-on-black display, which was a modified RCA XL-100 black and white television. The color of the screen text was light bluish (the standard "P4" phosphor used in black-and white televisions). Green and amber filters, or replacement tubes to make the display easier on the eyes, were common aftermarket items. Later models came with a green-on-black display.
Because of bandwidth problems in the interface card that replaced the TV's tuner, the display would lose horizontal sync if large areas of white were displayed; a simple hardware fix (involving less than half an hour's work) could be applied to correct that.

Layout of characters and pixels on the TRS-80 display
The video hardware could only display text at 64 or 32 characters wide by 16 lines of resolution.[7] This was because the video memory system used a single kilobyte of video memory. Seven of the bits of each byte were used to display ASCII characters, with the eighth bit used to differentiate between text and "semigraphics" characters.
Primitive graphics ("text semigraphics," rather than a true bitmap) could be displayed because the upper 64 characters of the 128 character set displayed as a grid of 2×3 blocks (very similar to Teletext). BASIC routines were provided which could write directly to this virtual 128×48 grid.
The original TRS-80 Model I could not differentiate between upper and lower characters in display memory. With only seven 1-bit-wide memory chips, the 8th bit was faked by circuitry that forced uppercase characters. The display hardware did have lowercase letters, but without descenders. In order to display lower case, one had to add an eighth memory chip. This modification became a popular third-party add-on, along with a character chip with descenders for the lowercase letters. Later models came with the hardware for lowercase character set to be displayed with descenders.
Any access to the screen memory caused "flicker" on the screen. The bus arbitration logic would block video display while access was given to the CPU, causing a short black line. This had little effect on normal BASIC programs, but fast programs made in assembly language could be affected. Many software authors were able to minimize this effect. Notwithstanding this primitive display hardware, many arcade-style games were available for the Tandy TRS-80.
The Model 1 had no sound hardware. Square wave tones could be produced by outputting data to the cassette port and plugging headphones or an amplifier into the Data Out line. Some games used this ability for sound effects.

Cassette tape drive

User data was originally stored on cassette tape. Radio Shack's model CTR-41 cassette recorder was included with the $599 package.[12]:3-4 The cassette tape interface was very slow and erratic;[15] it was sensitive to audio volume changes, and the machine only gave the very crudest indication as to whether the correct volume was set, via a blinking character on screen when data was being loaded. To find the correct volume, one would sometimes have to attempt to load a program once adjusting volume until the machine picked up the data, then reset the machine, rewind the tape and attempt the load again. Users quickly learned to save a file three or more times in hopes that one copy would prove to be readable. Automatic gain control or indicator circuits could be constructed to compensate for this (the owner's manual provided complete circuit diagrams for the whole machine, including the peripheral interfaces, with notes on operation). An alternative tape interface could receive transmissions from the BBC's Chip Shop programme in the UK, which broadcast software for several different microcomputers over the radio. A special program (loaded using the conventional tape interface) was needed to access the custom interface. Tandy eventually replaced the CTR-41 unit with the CTR-80 which had built-in AGC circuitry (and no volume control). This helped the situation, but tape operation was still unreliable.
TRS-80s with Level I BASIC read and wrote tapes at 250 bits per second (31.25 bytes per second); Level II BASIC doubled this to 500 bits per second (62.5 bytes per second). Some programmers wrote machine language programs that would increase the speed to up to 1800 bits per second without loss in reliability.
For loading and storing data, no hardware controller existed. Instead, the processor created the sound itself by switching the output voltage between three states, creating very crude sine wave audio.
The first models of the Model I also had problems reading from the cassette drives. Tandy eventually offered a small board which was installed in a service center to correct earlier models. The ROMs in later models were modified to correct this.

Expansion interface

The TRS-80 did not use the S-100 bus like other Z80-based computers.[7] A proprietary Expansion Interface (E/I) provided several important features - the ability to expand up to 48K of RAM, a floppy disk controller, a real-time clock, a second cassette port, an RS-232 port (as an option) and a Centronics parallel printer port.[16]
Originally, one could not print from the Model I without purchasing an Expansion Interface. However, Tandy Corp. soon sold a printer-only Interface for the Model I for approx. 300 Deutschmark in Germany.
The Expansion Interface was the most troublesome part of the TRS-80 system. It went through several revisions. A pre-production version is said to have looked completely different, and to have had a card cage. Its edge card connectors tended to oxidise due to the use of two different metals in the contacts, and required periodic cleaning with a pencil eraser. The expansion unit required a second power supply, identical to the base unit power supply; an interior recess held both power supplies.
Since the cable connecting the expansion interface carried the system bus, it was kept short (about two inches). This meant that the user had no choice but to place it directly behind the computer with the monitor on top of it. This caused problems if one owned a monitor whose case did not fit the mounting holes. Also, the loose friction fit of the edge connector on the already short interconnect cable created the precarious possibility of disconnecting the system bus from the CPU if either unit happened to be moved during operation. One reviewer compared the resulting collection of wires connecting the TRS-80's various components to the snakes in Raiders of the Lost Ark.[15]

Floppy disk drives

Radio Shack did not offer a floppy drive for the TRS 80 until 1978. To use the Model I with a disk operating system,[16]:14-15 one had to buy the Expansion Interface, which included a single density floppy disk interface (formatted capacity of 85k). This was based on a Western Digital 1771 single density floppy disk controller chip. Four floppy drives could be used with the Model I in a daisy-chain.
Since the interface lacked a separate external data separator, it was very unreliable in practice.[15] Much of the unreliability was due to bugs in Radio Shack's early version(s) of TRS-DOS. The 1771 could not report its status for a short interval (several instruction cycles) after it received a command. A common method of handling this was to issue a command to the 1771, perform several "NOP" instructions, then query the 1771 for command status. Early TRS-DOS neglected to use the required wait period, instead querying the chip immediately after issuing a command, and thus false status was often returned to the OS, causing various errors and crashes. If the 1771 was handled correctly by the OS, it was actually fairly reliable.
Double-density floppy disks
A data separator and a double density disk controller (based on the WD 1791 chip) were made by Percom (a Texas peripheral vendor), LNW, Tandy and others. The Percom Doubler added the ability to boot and use Double Density Floppies (they provided their own modified TRSDOS called DoubleDOS), and included the Data Separator. The LNDoubler added the ability to read and write from 8" diskette drives for over 1.2mb of storage. Near the end of the Model I's lifespan in 1982, double-density drives became available for it.
Double-sided floppy disks
All TRS-80 disk formats were soft-sectored with index-sync, and except for some very early Shugart drives (recognizable by their spiral-cam head positioner), all TRS-80 floppy drives were 40-track double-density models. The combination of 40 tracks and double-density gave a maximum capacity of 180 kilobytes per single-sided floppy disk. However, the use of index-sync meant that a "flippy disk" required a second index hole and write-enable notch. One could also purchase factory-made "flippies", or format the back side for Apple systems (as some software publishers of the era did).
The drives sold by Radio Shack were 35-track models with a 160K capacity.

Hard drive

Radio Shack introduced a 5MB hard-drive unit for the TRS-80. The size of the unit was about the same as a modern desk-top computer enclosure. The unit had a list retail price of approximately $1500.


One unusual peripheral offered was a "Quick Printer", an electrostatic rotary printer that scanned the video memory through the same bus connector used for the expansion interface, and printed an image of the screen onto aluminum-coated paper in about a second.[16]:16 Unfortunately, it was incompatible with both the final, buffered version of the expansion interface, and with the "heartbeat" interrupt used for the real-time clock under Disk BASIC. This could be overcome by using special cabling, and by doing a "dummy" write to the cassette port while triggering the printer.
Two other printers were offered: one for 57 mm metal coated paper, selling for approximately 600 Deutschmark in Germany, and one built by Centronics for normal paper, costing at first 3000 Deutschmark, later sold at approximately 1500 Deutschmark in some stores. It had only 7 pins, so letters with descenders such as lowercase "g" did not reach under the baseline, but were elevated within the normal line.


Three versions of the BASIC programming language were produced for the Model I. Level I BASIC fit in 4 KB of ROM, and Level II BASIC fit into 12 KB of ROM. Level I was single precision only and had a smaller set of commands. Level II introduced double precision floating point support and had a much wider set of commands. Level II was further enhanced when a disk system was added, allowing for the loading of Disk BASIC.[7]
Level I Basic was based on Li-Chen Wang's free Tiny BASIC, additional functions added by Radio Shack.[9] It achieved a measure of noteworthiness due in large part to its outstanding manual,[7] written by David Lien, which presented lessons on programming with text and humorous graphics, making the subjects very easy to understand. It had only two string variables (A$ and B$), 26 numeric variables (A - Z) and one array, A(). Code for functions like SIN(), COS() and TAN() was not included in ROM but printed at the end of the book. The only error messages were: "WHAT?" for syntax errors, "HOW?" for arithmetic errors such as division by zero, and "SORRY" for out of memory errors.
Level I BASIC was not tokenized—reserved words were stored literally. In order to maximize the code that could be crammed into 4K of memory users could enter abbreviations for reserved words. For example, writing "P." instead of "PRINT" thus saving 3 bytes.
Level II BASIC was licensed from Microsoft. It was a cut-down version of the 16 KB Extended BASIC, since the Model I had 12 KB of ROM space. The accompanying manual was not nearly as colorful and suited for beginning programmers as the Level I BASIC manual. Original Level I BASIC-equipped machines could be retrofitted to Level II through a ROM replacement performed by Radio Shack for a fee (originally $199). Users with Level I BASIC programs stored on cassette had to convert these to the non-tokenized Level II BASIC before use. A utility for this was provided with the Level II ROMS.
Disk BASIC added the ability to perform disk I/O, and in some cases (NewDos/80, MultiDOS, DosPlus, LDOS) added powerful sorting, searching, full screen editing, and other features. Level II BASIC recognized some of these commands and issued a "?L3 ERROR", suggesting that a behind-the-scenes change of direction intervened between the recording of the Level II ROMs and the introduction of Disk BASIC.
Microsoft also marketed a tape-cassette based enhanced BASIC called Level III BASIC. This added most of the functions in the full 16 KB version of BASIC.

Software applications

Blackjack and backgammon came with the TRS-80 for free, and at its debut Radio Shack offered four payroll, personal finance, and educational programs, all on cassette.[7][12]:3 Many leading developers, and independent software companies such as Big Five, produced unlicensed versions of popular arcade hits like Namco's Pac-Man and Galaxian, Atari's Centipede, Exidy's Targ and Stern Electronics' Berzerk (with digitized speech). Some companies ported games from other home computers of the era, such as the original Zork adventure game. There were also many games unique to the TRS-80, including shooters like Cosmic Fighter and Defence Command and strange experimental programs such as Dancing Demon, which was not strictly speaking a game but did have significant entertainment value.
A full suite of office applications were also available, including the VisiCalc and As-Easy-As spreadsheets and the Lazy Writer, Electric Pencil and Scripsit word processors.
Utility software such as Stewart Software's Toolkit offered the first sorted directory, decoding or reset of passwords, and the ability to eliminate parts of TRS-DOS that were not needed in order to free up floppy disk space. They also produced the On-Line 80 BBS, a TRS-DOS based Bulletin Board System.
TRS-DOS—Radio Shack's operating system for its TRS-80 computers—had significant limitations, opening the market for various alternative OSes, including NewDOS, a third-party rival sold by a company called Apparat Personal Computers, which went out of business in 1987. Others included DoubleDOS, DOSPlus, LDOS, MicroDOS, NEWDOS/80, UltraDOS, later called Multidos, and VTOS. The last versions (6.x) of TRSDOS were actually renamed LS-DOS (aka, LDOS).
CP/M became a standard OS for business use on Z80-based machines, and all TRS-80s got versions of it. However, the Model I's CP/M proved largely useless since the computer had its video memory in the normal location where the OS loaded. This meant that CP/M software had to be explicitly rewritten for the Model I, destroying its main advantage of portability (normally CP/M applications such as WordStar could be interchanged between different incompatible machines with a configuration program being used to set up things such as the video display format).


TRS-80 Model I clone, the DGT-100 by DIGITUS Ind. Com. Serv. de Eletrônica Ltda.
Many clones of the TRS-80 Model I came on the market: the Lobo Max-80 (Lobo also produced their own version of the Expansion Interface), the LNW-80 Models I/II and Team computers (LNW also produced an alternate version of the Expansion Interface), and the Dutch Aster CT-80, a computer that could run both TRS-80 and CP/M software, and also had all the improvements of the later Model III.
EACA in Hong Kong made a Model I clone that was marketed around the world under different names with modifications. In Australia and New Zealand it was the Dick Smith System-80, in North America it was PMC-80 and PMC-81, in Hungary the HT-1080Z, in South Africa the TRZ-80, and in Western Europe it was Video Genie. The expansion bus was different and EACA also made its own Expansion Interface to fit it. There were several versions, and it was later split into a 'home' and a 'business' version, Genie I and II, and System-80 Mark I and II, where the II would have a numeric keypad instead of the built-in cassette player. EACA's Colour Genie was also based on TRS-80 Model I but with improved graphics and other changes, reducing its compatibility.
In Brazil several manufacturers developed clones for models I/III/IV. Dismac series D8000/D8001/D8002 (all three Model I clones) were the first personal computers manufactured in industrial scale in South America. Digitus made the DGT-100 and DGT-1000, Prologica made the highly-successful CP300 and CP500 series (both Model III clones), Sysdata Eletrônica Ltda. made the Sysdata Jr. Prologica also made the CP400 / CP 400II which were copies of the TRS-80 Color Computer, with the external case being almost a copy of the Timex Sinclair 2068.
In Germany, S.C.S. GmbH in Mörfelden- Waldorf offered the Komtek-I Model I clone. Noteworthy was its four relay switching outputs.
In the Soviet Union, some ideas from the TRS-80 were used in development of the Корвет (Corvette) home/school computer.

Business systems

Tandy 10

Tandy's first design for the business market was a desk-based computer known as the Tandy 10 Business Computer System, which was released in 1978 but quickly discontinued.

Model II and 12

TRS-80 Model II
In October 1979, Tandy began shipping the Model II, which was targeted to the small-business market. Creative Computing in 1984 called it a "state-of-the-art business machine" that "might have taken the business market by storm had it not had a nameplate reading 'Radio Shack.'"[8]
The Model II was not an upgrade of the Model I, but an entirely different system. As a professional business machine, it used state-of-the-art hardware and had numerous features not found in the primitive Model I such as DMA, vectored interrupts, a detachable keyboard, and port instead of memory-mapped I/O. It sported 80x25 text and a singled-sided 500k 8" floppy drive, and either 32 or 64k of RAM, along with two RS-232 ports and a Centronics-standard parallel port. The video memory was not mapped into the main address space or directly accessible by the CPU (only through indirect register writes). Unlike most computers, it had no BIOS ROM except a small boot loader (the BIOS was loaded off the boot floppy). Because of this and the use of port I/O, almost all of the Model II's memory could be used by software. The Model II ran the TRSDOS operating system (renamed to TRSDOS-II starting with version 4.0) and BASIC. TRSDOS for the Model II was not compatible with TRSDOS for the Model I; thus the Model II never had the same breadth of available software as the Model I (a situation aggravated by the fact that Tandy discouraged third-party software development[citation needed]). This was somewhat mitigated by the availability of the CP/M operating system for the Model II from third parties such as Pickles & Trout. Three internal expansion slots could be used for add-on cards such as additional serial ports and a video board that allowed bitmap graphics. Since the Model II did not boot into BASIC (which was provided on disk), it had a more professional feel to it than some machines such as the Commodore PET[citation needed] (which may have failed in the business market partially because of its using BASIC as an OS[citation needed]).
Tandy offered a desk custom-designed for the Model II for US$370. It could hold an additional three 8" disk drives or up to four 8.4MB hard drives (the Model II allowed three external floppy drives to be daisy-chained to it).
The Model II was replaced in 1982 by the Model 12, which used half-height ("thinline") double-sided floppy drives, and integrated most of the Model II electronics into a single main board.[17] The video/keyboard card plugged into a single slot in the main board. An expansion card cage was available as an option, allowing more plug-in cards. The Model 12 was essentially a Model 16B (described below) without the Motorola processor, and could be upgraded to a Model 16B.

Model III

TRS-80 Model III
In July 1980 Tandy released the Model III. The improvements of the Model III over the Model I included built-in lower case, a better keyboard, 1500-baud cassette interface, and a faster (2.03 MHz) Z-80 processor. With the introduction of the Model III, Model I production was discontinued as it did not comply with new FCC regulations as of 1 January 1981 regarding electromagnetic interference.[10][15][18] The Model I radiated so much interference that while playing games an AM radio placed next to the computer could be used to provide sounds.[19]
The Model III could run about 80% of Model I software, but used an incompatible disk format.[10] Customers and developers complained of bugs in its BASIC and the TRSDOS operating system.[20] The computer also came with the option of integrated disk drives. Since they took power from the same supply as the motherboard and screen, which was not upgraded for the disk drive models, it was common to see the screen image shrink noticeably during drive access.

Model 4

The successor to the Model III was the Model 4 (April 1983, with "4" written as an Arabic numeral), which included the capability to run CP/M.
Running CP/M had previously only been possible via a hardware modification that remapped the BASIC ROMs away from memory address zero, such as the third-party add-on sold as the Omikron Mapper board, or by running a version of CP/M modified to run at a starting address other than zero. However, this also required modified applications, since the area of memory at zero contained the vectors for applications to access CP/M itself. The Model 4 also added an 80 column by 24 line video display mode required for CP/M compatibility.
The Model 4 shipped with TRSDOS 6, an enhanced version of LDOS by Logical Systems and a vastly superior operating system to Tandy's earlier TRSDOS offerings. When the Model 4 booted into TRSDOS 6 the video display switched into 80×24 mode and the entire 64KB address space was mapped as RAM. The Model 4 was also capable of running all Model 3 software when a Model 3 operating system disk was detected and loaded during bootup with a 64×16 video mode and Model 3 ROMs mapped from address zero.

TRS-80 Model 4P
The Model 4 also had the ability to display 640×240 or 512×192 high-resolution monochrome graphics with an optional board. A "luggable" version known as the Model 4P (1983) was a self-contained unit with a case design similar to that of a portable sewing machine.
Early versions of the Model 4 mainboard were designed to accept a Zilog Z8000 16 bit CPU upgrade board to replace the Z80 8 bit CPU but this option was never released.

Model 16, Model 16B, and Tandy 6000

Tandy later released the TRS-80 Model 16, as the follow-on to the Model II; an upgrade kit was available for Model II systems. The Model 16 added a 6 MHz, 16-bit Motorola 68000 processor and memory card, keeping the original Z-80 as an I/O processor. It had two half-height ("thinline") double-sided 8-inch floppy drives, though the Model II upgrade did not replace the floppy drive. It could run either TRSDOS-16 or Xenix, Microsoft's version of UNIX. Of the two operating systems, Xenix was far more popular. TRSDOS-16 was essentially a layer of code providing a 68000 interface to Model II TRSDOS, with no additional features and little compatible software. 68000 functionality was added as an extension, loading 68000 code into the 68000 memory via a shared memory window with the Z80.
Xenix, on the other hand, offered the full power of UNIX System III including multi-user support. The Model 16 family with Xenix became a popular system for small business, with a relatively large library of business and office automation software for its day. Tandy offered multi-user word processing (Scripsit 16), spreadsheet (Multiplan), and a 3GL "database" (Profile 16, later upgraded to filePro 16+), as well as an accounting suite with optional COBOL source for customization. RM-COBOL, Basic, and C were available for programming, with Unify and Informix offered as relational databases. A kernel modification kit was also available.
TRS-Xenix was notable for being a master/slave implementation, with all I/O being performed by the Z80 while all processing was done within the otherwise I/O-free 68000 subsystem.
The Model 16 evolved into the Model 16B, and then the Tandy 6000 HD, gaining an internal hard drive along the way and switching to an 8 MHz 68000. Tandy offered 8.4MB, 15 MB, 35 MB, and 70 MB external hard drives, up to 768 KB of RAM, and up to six additional RS-232 serial ports supporting multi-user terminals. Additional memory and serial port expansion options were available from aftermarket companies.
Internal variants of the Model 16 architecture were built running at speeds in excess of 10 MHz, 68010 processors, up to 8Mb of RAM, SCSI disk interfaces, and up to 12 RS-232 ports.[citation needed]

Other systems

Color Computers

Tandy also produced the TRS-80 Color Computer (CoCo), based on the Motorola 6809 processor. This machine was clearly aimed at the home market, where the Model II and above were sold as business machines. It competed directly with the Commodore 64, Apple II, and Atari 8-bit family of computers. OS-9, a multitasking, multi-user operating system was supplied for this machine.

Model 100 line

In addition to the above, Tandy produced the TRS-80 Model 100 series of laptop computers. This series comprised the TRS-80 Model 100, Tandy 102, Tandy 200 and Tandy 600. The Model 100 was designed by the Japanese company Kyocera with software written by Microsoft. (The Model 100 firmware was the last Microsoft product to which Bill Gates was a major code contributor.[21])
The Model 100 had an internal 300 baud modem, built-in BASIC, and a limited text editor. It was possible to use the Model 100 on essentially any phone in the world with the use of an optional acoustic coupler that fit over a standard telephone handset. The combination of the acoustic coupler, the machine's outstanding battery life (it could be used for days on a set of 4 AA batteries), and its simple text editor made the Model 100/102 popular with journalists in the early 1980s. The Model 100 line also had an optional bar code reader, serial/RS-232 floppy drive and a Cassette interface.
Also available as an option to the Model 100 was an external expansion unit supporting video and a 514" disk drive, connected via the 40-pin expansion port in the bottom of the unit.

Tandy 200

Tandy 200 beside a Sony Vaio laptop
The Tandy 200 was introduced in 1984 as a higher-end complement to the Model 100. The Tandy 200 had 24 KB RAM expandable to 72 KB, a flip-up 16 line by 40 column display, and a spreadsheet (Multiplan) included. The Tandy 200 also included DTMF tone-dialing for the internal modem. Although less popular than the Model 100, the Tandy 200 was also particularly popular with journalists in the late 1980s and early 1990s.


The MC-10 was a short-lived and little-known Tandy computer, similar in appearance to the Sinclair ZX81.
It was a small system based on the Motorola 6803 processor and featured 4 KB of RAM. A 16 KB RAM expansion pack that connected on the back of the unit was offered as an option as was a thermal paper printer. A modified version of the MC-10 was sold in France as the Matra Alice.
Programs loaded using a cassette which worked much better than those for the Sinclair.[citation needed] A magazine was published which offered programs for both the CoCo and MC-10 but very few programs were available for purchase. Programs for the MC-10 were not compatible with the CoCo.

A PC-2 ready for use

Pocket Computers

The TRS-80 brand was also used for a line of Pocket Computers which were manufactured by Sharp or Casio, depending on the model.

PC-compatible computers

In the early 1980s, Tandy began producing a line of computers that were "DOS compatible": able to run MS-DOS and certain applications, but not fully compatible with every nuance of the original IBM PC systems. The first of these was the Tandy 2000, followed later by the less expensive Tandy 1000. As margins decreased in PC clones, Tandy was unable to compete and stopped marketing their own systems.
Originally, Tandy offered computers manufactured by Tandon Corporation, and then started producing their own line of systems.[citation needed]
The Tandy 2000 system was similar to the Texas Instruments Professional Computer in that it offered better graphics, a faster processor (80186) and higher capacity disk drives (80 track double sided 800k 5.25 drives) than the original IBM PC
However, around the time of its introduction, the industry began moving away from MS-DOS compatible computers and towards fully compatible clones; later Tandy offerings moved toward full PC hardware compatibility.
The later Tandy 1000 systems and follow-ons were also marketed by DEC, as Tandy and DEC had a joint manufacturing agreement.[22]


Emulators for the TRS-80 are listed below.

See also


  1. ^ a b Forster, Winnie (2005). The encyclopedia of consoles, handhelds & home computers 1972–2005. GAMEPLAN. pp. 17. ISBN 3-00-015359-4.
  2. ^ Mooallem, Jon (April 19, 2010). "The Lost Tribes of RadioShack: Tinkerers Search for New Spiritual Home". Wired. Retrieved 3 August 2012.
  3. ^ "Most Important Companies". Byte Magazine. September 1995. Retrieved June 10, 2008.
  4. ^ "Radio Shack TRS-80 MICRO COMPUTER SYSTEM". Retrieved May 6, 2010.
  5. ^ a b c Welch, David and Theresa (2007). Priming the Pump: How TRS-80 Enthusiasts Helped Spark the PC Revolution. Ferndale, Michigan: The Seeker Books. ISBN 978-0-9793468-0-4.
  6. ^ a b c d Michael Swaine (1981-08-31). "How the TRS-80 Was Born". InfoWorld. pp. 40–43. Retrieved February 28, 2011.
  7. ^ a b c d e f g h i Thomas, Wes (1980). "Radio Shack's $600 Home Computer". The Best of Creative Computing 3: 290–291.
  8. ^ a b c d Ahl, David (1984-11). "Tandy Radio Shack enters the magic world of computers". Creative Computing. pp. 292. Retrieved February 26, 2011.
  9. ^ a b c Leininger, Steven W. (September 1977). "TRS-80 architect reminisces about design project". San Diego Computer Society. Retrieved February 28, 2011.
  10. ^ a b c Hogan, Thom (1981-08-31). "A Look at Radio Shack's Five Computers". InfoWorld. pp. 44–45. Retrieved February 28, 2011.
  11. ^ a b Bartimo, Jim (1984-08-20). "RADIO SHACK POLISHES ITS IMAGE". InfoWorld. pp. 47–52. Retrieved February 28, 2011.
  12. ^ a b c 1977 TRS-80 Radio Shack Introduction Brochure. Radio Shack. 1977.
  13. ^ Brown, Chris (1980-01). "The Tandy Story". 80 Microcomputing. pp. 26–28. Retrieved March 21, 2011.
  14. ^ "John Roach, Tandy/RadioShack". Consumer Electronics Association. Retrieved February 26, 2011.
  15. ^ a b c d e Hogan, Thom (1981-08-31). "The Radio Shack TRS-80 Model III Computer". InfoWorld. pp. 35–37. Retrieved February 28, 2011.
  16. ^ a b c 1978 Radio Shack Tandy TRS-80 Computer Catalog RSC-02. Radio Shack. 1978.
  17. ^ Tim Daneliuk, Hardware Review TRS 80 Model 12 , 'a refined TRS 80 Model II' , Info World August 22, 1983 page 50
  18. ^ Robertson, Nancy (1980-12). "Model I Caught By FCC Fallout". 80 Microcomputing. pp. 51, 56. Retrieved March 21, 2011.
  19. ^ "John Freire audio interview discussing the use of an AM radio for game sounds on the Model I". Retrieved July 20, 2010.
  20. ^ Freiberger, Paul (1981-08-31). "Bugs in Radio Shack TRS-80 Model III: How Bad Are They?". InfoWorld. pp. 49. Retrieved February 28, 2011.
  21. ^ Gates, Bill. Interview with Bill Gates. with David Allison. Transcript of a Video History Interview by the National Museum of American History, Smithsonian Institution. Retrieved 2008-01-08.
  22. ^ "COMPANY NEWS; Digital Sets Plan to Build Its Own PC's", New York Times, February 8, 1982

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TRS-80 Color Computer

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16k TRS-80 Color Computer 1
Developer Tandy Corporation
Manufacturer Motorola
Type Home computer
Release date 1980
Introductory price US$399
Discontinued 1991
Operating system Color BASIC 1.0 / 2.0 / OS-9
CPU Motorola 6809E @ 0.895 MHz / 1.79 MHz
Memory 4 KB / 16 KB / 32 KB/ 64 KB / 128 KB / 512 KB
Graphics MC6847 Video Display Generator (VDG)
The Radio Shack TRS-80 Color Computer (also marketed as the Tandy Color Computer and affectionately nicknamed CoCo) was a home computer launched in 1980. It was one of the earliest of the first generation of computers marketed for home use in English-speaking markets. While the model was eventually eclipsed by the onset of the IBM PC clones, enthusiasts have continued to affectionately tinker with the "CoCo" to the present day.



Despite bearing the TRS-80 name, the "Color Computer" was a radical departure from earlier TRS-80 Models - in particular it had a Motorola 6809E processor, rather than the TRS-80's Zilog Z80.
The Motorola 6809E was a very advanced processor, but was correspondingly more expensive than other more popular microprocessors. Competing machines such as the Apple II, Commodore VIC-20, the Commodore 64, the Atari 400, and the Atari 800 were designed around a combination of the much cheaper MOS 6502, itself essentially an enhanced clone of the Motorola 6800. Some of these competing machines were paired with dedicated sound and graphics chips and were much more commercially successful in the 1980s home computer market. Steve Wozniak once commented that the 6502 was 1/4 the price of the Motorola 6800 when the original Apple was being developed in the late 70s. By 1986 prices for 8 bit processors had dropped dramatically from the late 70s, but the MC6809 was still just over twice the price of a MOS6502 (6809/6809E - $5.95; MOS6502 - $2.79).[1]
The Tandy Color Computer line started in 1980 with what is now called the CoCo1 and ended in 1991 with the more powerful yet similar CoCo 3. It was one of the more powerful 8 bit computers of its day. All three CoCo models maintained a very high level of software and hardware compatibility, with few programs written for the older model not running on the newer. The converse cannot be claimed, obviously, due to the greater capabilities of the newer CoCo models. The death knell of the CoCo was the advent of lower cost IBM PC clones, the same event that spelled the end of other models competing in the home computer market.
The CoCo lacked some of the graphics and sound capabilities of other home computers, but made up for it in computing power and ease of programming in BASIC. Combined with the versatile BASIC, the robust, easy-to-interface-to design has long made it an experimenter's favorite.

Origin and history

The TRS-80 VideoTex Terminal, circa 1980
The TRS-80 Color Computer started out as a joint venture between Tandy Corporation of Fort Worth, Texas and Motorola Semiconductor, Inc. of Austin, to develop a low cost home computer in 1977.
The initial goal of this project, called "Green Thumb", was to create a low cost Videotex terminal for farmers, ranchers, and others in the agricultural industry. This terminal would connect to a phone line and an ordinary color television and allow the user access to near real-time information useful to their day-to-day operations on the farm.
Motorola's MC6847 Video Display Generator (VDG) chip was released about the same time as the joint venture started and it has been speculated that the VDG was actually designed for this project. At the core of the prototype "Green Thumb" terminal, the MC6847, along with the MC6809 Microprocessor Unit (MPU), made the prototype a reality by about 1978. Unfortunately, the prototype contained too many chips to be commercially viable. Motorola solved this problem by integrating all the functions of the many smaller chips into one chip, the MC6883 Synchronous Address Multiplexer (SAM). By that time in late 1979, the new and powerful Motorola MC6809 processor was released. The SAM, VDG, and 6809 were combined and the AgVision terminal was born.
The AgVision terminal was also sold through Radio Shack stores as the VideoTex terminal around 1980. Internal differences, if any, are unclear, as not many AgVision terminals survive to this day.
With its proven design, the VideoTex terminal contained all the basic components for a general purpose home computer. The internal modem was removed, and I/O ports for cassette storage, serial I/O, and joysticks were provided. An expansion connector was added to the right side of the case for future enhancements and program cartridges ("Program Paks"), and a RAM button (a sticker indicating the amount of installed memory in the machine) covered the hole where the Modem's LED "DATA" indicator had been. On July 31, 1980, Tandy announced the TRS-80 Color Computer. Sharing the same case, keyboard, and layout as the AgVision/VideoTex terminals, at first glance it would be hard to tell the TRS-80 Color Computer from its predecessors.
The initial model (catalog number 26-3001) shipped with 4K of Dynamic Random Access Memory (DRAM) and an 8k Microsoft BASIC interpreter in ROM. Its price was $399. Within a few months, Radio Shack stores across the US and Canada began receiving and selling the new computer.

Differences from earlier TRS-80 models

The Color Computer, with its Motorola 6809E processor, was a radical departure from the Z80-based TRS-80 Models. Indeed the "80" in "TRS-80" stood for "Z80". For a time, the CoCo was referred to internally as the TRS-90 in reference to the "9" in "6809". However this was dropped and all CoCos sold as Radio Shack computers were called TRS-80 in spite of the processor change.
Like its Z80-based predecessors, the CoCo shipped with BASIC, but in this case Tandy licensed Microsoft BASIC. As with the Z80 systems, there were multiple "levels" of BASIC. In the case of the CoCo they were the standard Color BASIC and Extended Color BASIC. Beyond that, Disk Extended Color BASIC came with the floppy controller, and on the CoCo 3, "Super" Extended Color BASIC extensions were added by Microware. Additional ROMs such as JDOS (Copyright J&M Systems) were available to enable the use of double sided disc drives.
The CoCo, which could display eight colors at once, was designed to be attached to a color television set, whereas the Z80 machines used monochrome computer monitors, often built into the case. The CoCo also featured an expansion connector for program cartridges (mostly games) and other expansion devices, such as floppy disk controllers and modems. In this way it shared some similarity to the Atari 2600, Atari 400/800 and other cartridge-capable game consoles and computers. Tandy also released a Multi-Pak Interface which allowed switching quickly among four cartridges mounted at the same time. This was similar in concept to the Model I's Expansion Interface.
Unlike some Z80 models, the CoCo did not come with a built-in floppy drive. The CoCo was designed to save and load programs and data from a standard audio cassette deck. Although slow (though at an average of 1500 bit/s it was faster than the Commodore 1541) and sometimes unreliable, this made the CoCo more affordable as a home computer. Tandy eventually offered a floppy disk drive controller for the CoCo as a cartridge. Both the CoCo and earlier TRS-80s shared the WD17xx series floppy disk controllers and 35 (later 40) track industry-standard floppy drives.
Even with the add-on floppy drive, the CoCo did not have a true DOS until third-party operating systems such as TSC FLEX9 (distributed for the CoCo by Frank Hogg Laboratories) and Microware's multi-user, multi-tasking OS-9 were available. However, a disk-based CoCo did contain Disk Extended Color BASIC on an internal ROM in the controller cartridge that gave the BASIC user the ability to save and load programs from the disk and store and retrieve data from disk in various ways.
Some non-program expansion cartridges included a sound/voice synthesiser (which led to the CoCo being used as an accessibility device for the disabled), 300 baud modem pak, RS232 pak, a hard drive controller, stereo music adapter, floppy disk controller, input tablet, and other accessories. The CoCo was the first Tandy computer to have a mouse available for it.


There were three versions of the Color Computer:

Color Computer 1 (1980–1983)

4k TRS-80 Color Computer from 1981, 26-3001
The original version of the Color Computer shipped in a large silver-gray case with a calculator-like "chiclet keyboard", and was available with memory sizes of 4K (26-3001), 16K (26-3002), or 32K (26-3003). Versions with at least 16K of memory installed shipped with standard Microsoft Color Basic or (optionally) Extended Color Basic. It used a regular TV for display, and TV-out was the only available connection to a display device.
The early versions of the CoCo 1 had a black keyboard surround, the TRS-80 nameplate above the keyboard to the left side, and a RAM badge ("button") affixed on the top and right side of the case. Later versions removed the black keyboard surround and RAM button, and moved the TRS-80 nameplate to the mid-line of the case.
Initial versions of the CoCo were upgraded to 32K by means of piggybacking two banks of 16K memory chips and adding a few jumper wires. A later motherboard revision removed the 4K RAM option and were upgraded to 32K with "half-bad" 64K memory chips as a cost-cutting measure. These boards have jumpers marked HIGH/LOW to determine which half of the memory chip was good. This was transparent to the BASIC programmer since in either configuration 32K of memory was available. As memory production yields improved and costs went down, many (perhaps most) 32K CoCo 1s were shipped with perfectly good 64K memory chips; many utilities and programs began to take advantage of the "hidden" 32K.
Eventually the 32K memory option was dropped entirely and only 16K or 64K versions were offered. All versions that shipped with standard Color BASIC could be upgraded to Extended BASIC by simply plugging a ROM into an empty socket provided on the motherboard.
Toward the end of the CoCo 1 production run, a version of the "CoCo" with a white case, called the TDP-100, was marketed through Tandy Data Products (TDP) and sold through a different distribution channel. Except for the nameplate and case, the TDP-100 was identical to the CoCo 1.
At some point after this, both the Coco and the TDP-100 shipped with a white case which had ventilation slots that ran the entire length of the case, rather than only on the sides. This ventilation scheme was carried over to the CoCo 2.
Some late versions of the CoCo also shipped with a modified keyboard, often referred to as the "melted" keyboard, which had bigger keycaps but a similar rubbery feel.
A number of peripherals were available: tape cassette storage, serial printers, a 5.25 inch floppy disk drive, a pen and graphics tablet called the "X-Pad", speech and sound generators, and joysticks.
16k TRS-80 Color Computer I  
I/O ports and cartridge slot on the TRS-80 Color Computer I  
Late "white" model TRS-80 Color Computer I  
Tandy Data Products TDP-100 (64K badge was added by user)  

Color Computer 2 (1983–1986)

Final production 64K Tandy Color Computer 2, showing full-travel keyboard (26-3127B)
During the CoCo 1 production run, much of the discrete support circuitry had been re-engineered into a handful of custom integrated circuits, leaving much of the circuit board area of the CoCo 1 as empty space. To cut production costs, the case was shortened by about 25% and a new, smaller power supply and motherboard were designed. The "melted" keyboard from the white CoCo 1 and the TDP-100 style ventilation slots were carried over. Aside from the new look and the deletion of the 12 volt power supply to the expansion connector, the computer was essentially 100% compatible with the previous generation. The deletion of the 12 volt power supply crippled some peripherals such as the original floppy disk controller, which then needed to be upgraded, installed in a Multi-Pak interface, or supplied with external power.
Production was also partially moved to Korea during the CoCo 2's life-span, and many owners of the Korean-built systems referred to them as "KoKos". Production in the USA and Korea happened in parallel using the same part numbers; very few, if any, differences exist between the USA built and Korean built CoCo 2 machines.
Upgraded BASIC ROMs were also produced, adding a few minor features and correcting some bugs. A redesigned 5-volt disk controller was introduced with its own new Disk BASIC ROM (v1.1). This controller added the "DOS" command which was used to boot the OS-9 operating system by Microware.
Later in the production run, the "melted" keyboard was replaced with a new, full-travel, typewriter-style keyboard.
The final significant change in the life of the CoCo 2 was made for the models 26-3134B, 26-3136B, and 26-3127B (16K standard, 16K extended, and 64K extended respectively). Internally this model was redesigned to use the enhanced VDG, the MC6847T1. This enhanced VDG allowed the use of lower case characters and the ability to change the text screen border color. However, for compatibility reasons neither of these features were used and are not enabled in BASIC. Midway during the production run of these final CoCo 2s, the nameplate was changed from "Radio Shack TRS-80 Color Computer 2" to "Tandy Color Computer 2". The red, green, and blue shapes were replaced with red, green, and blue parallelograms.
Early TRS-80 Color Computer 2 with "melted" keyboard  
PAL version of the TRS-80 Color Computer 2  

Color Computer 3 (1986–1991)

128k Tandy Color Computer 3, 26-3334
On July 30, 1986, Tandy announced the Color Computer 3 at the Waldorf-Astoria Hotel in New York City. It came with 128K of RAM, which could be upgraded to 512K. The keyboard surround and cartridge door plastic were changed from black to grey. The keyboard layout was revised, putting the arrow keys in a diamond configuration and adding CTRL, ALT, F1 and F2 keys. It sold in Radio Shack stores and Tandy Computer Centers for $219.95.
The CoCo 3 was compatible with most of the CoCo 2's peripherals. Most older software ran on it. Taking the place of the graphics and memory hardware in the CoCo 1 and 2 was an application-specific integrated circuit (ASIC) called the "GIME" (Graphics Interrupt Memory Enhancement) chip. The GIME also provided additional features:
  • Output to a composite video monitor or analog RGB monitor, in addition to the CoCo 1 and 2's TV output. This did much to improve the clarity of its output.
  • A paged memory management unit which broke up the 6809's 64k address space into 8x8K chunks. Although these chunks were considered to be too large by many programmers, the scheme would later allow third party RAM upgrades of up to 2 MB (256x8k).
  • Text display with real lowercase at 32, 40, 64, or 80 characters per line and between 16 and 24 lines per screen.
  • Text character attributes, including 8 foreground and 8 background colors, underline, and blink.
  • New graphics resolutions of 160, 256, 320 or 640 pixels wide by 192 to 225 lines.
  • Up to 16 simultaneous colors out of a palette of 64 displayable at one time (unless programming tricks were employed to display more).
Omitted from the GIME were the seldom-used SAM-created Semigraphics 8, 12, and 24 modes. A rumored 256 color mode (detailed in the original Tandy spec for the GIME)[2] has never been found.
Previous versions of the CoCo ROM had been licensed from Microsoft, but by this time Microsoft was not interested in extending the code further.[citation needed] Instead, Microware provided extensions to Extended Color BASIC to support the new display modes. In order to not violate the spirit of the licensing agreement between Microsoft and Tandy, Microsoft's unmodified BASIC software was loaded in the CoCo 3's ROM. Upon startup, the ROM is copied to RAM and then patched by Microware's code. Although this was a clever way of adding features to BASIC, it was not without some flaws: the patched code had several bugs, and support for many of the new hardware features was incomplete.
Microware also provided a version of the OS-9 Level 2 operating system shortly after launch. This OS featured memory-mapping (so each process had its own memory space up to 64K), windowed display, and a more extensive development environment that included a bundled copy of BASIC09. C and Pascal compilers were available. Various members of the CoCo OS-9 community enhanced OS-9 Level 2 for the CoCo 3 at Tandy's request, but Tandy stopped production of the CoCo 3 before the upgrade was officially released. Most of the improvements made it into NitrOS-9, a major rewrite of OS-9/6809 Level 2 for the CoCo 3 to take advantage of the added features and speed of the Hitachi 6309 (if the unit has the Hitachi CPU installed).[3]

Typical CoCo 3 system
The 6809 in the CoCo 1 and 2 ran at 0.895 MHz; the CoCo 3 runs at that frequency by default, but is software controllable to run at twice that rate; OS-9 takes advantage of that capability. Some models of CoCo 1 and 2 were also capable of running at this higher speed, but this was not supported or guaranteed.
A popular accessory was a high-resolution joystick adapter designed by CoCo enthusiast Steve Bjork. While it did increase the resolution of the joystick/mouse interface by a factor of ten, it did so at the expense of CPU time. A modified version of this interface was included with a software package by Colorware called CoCo-Max 3, by Dave Stamp. This was a MacPaint work-alike but added support for color graphics. This was a very desirable product for CoCo owners and combined with a MacWrite-like word processor called MAX-10 (also by Dave Stamp and internally named "MaxWrite"), provided much of the functionality of an Apple Macintosh, but with color graphics and at a fraction of the cost.
While the CoCo 3 featured many enhancements and was well received, it was not without problems and disappointments. As initially conceived, the CoCo 3 had much hardware acceleration and enhanced sound. However, internal politics crippled the design so it would not be perceived as a threat to the Tandy 1000.[citation needed] This again limited the platform's potential as a game console. Early versions of the GIME had DRAM timing issues which caused random freezes. Due to bugs in the GIME some features that were problematic were marked as "reserved" or "do not use" in the programming and service manuals.
The power supply was marginal, and some would overheat if the system memory was expanded to the full 512K capacity. Some CoCo 3 owners opted to add a small fan inside the case to keep it cool.

Prototypes and rare versions

A Color Computer 3 prototype.
Various prototypes for the CoCo have surfaced over the years. In the 1980s, Radio Shack stores were selling a keyboard that would plug directly into a CoCo 2, though not labeled as such. This keyboard was part of a production run for the never produced Deluxe Color Computer. The Deluxe CoCo was referenced in CoCo manual sets and specifically mentioned as having extra keys, lowercase video, and the ability to accept commands in lowercase. Later versions of the CoCo 2, labeled Tandy instead of TRS-80, had the ability to display true lowercase, but did not accept lowercase commands, although this capability was later available through A-DOS, a third-party replacement ROM for the Disk Controller.
Production model CoCo 3s have been found with different circuit board layouts and socketed chips. In 2005, a rare CoCo 3 prototype surfaced at the Chicago CoCoFEST, with a built-in floppy disk drive controller and other items still not identified. It also did not use a GIME chip. Instead, all the functionality of the GIME was created using separate chips. There is a hobbyist effort to try to reverse engineer these chips so a modern GIME can finally be produced.
There is also a prototype Ethernet interface for the Color Computer, displaying a board layout date of 1984, and a few other mystery boards that have yet to be examined. There is some evidence that Tandy killed the Ethernet interface at the last minute: an ad mentioning the networking options for some of Tandy's Z80-based computers claimed that the Color Computer would soon have networking capabilities, and the printed manual for an upgraded version of OS-9 Level One listed networking in the table of contents, but had no corresponding text in the body of the manual.

CoCo clones and cousins

The Dragon 32 and 64 computers were British cousins of the CoCo based on a reference design from Motorola that was produced as an exemplar of the capabilities of the MC6809E (MPU) when coupled with the MC6847 (Video Display Generator - VDG) and the MC6883 (Synchronous Address Multiplexer - SAM). The BIOS code for the Dragon 32 was rewritten based on specifications and API drawn up by Microsoft and, to a certain extent, PA Consulting of Cambridge. The Dragon was a much improved unit with video output in addition to the TV output of the CoCo and CoCo 2. It also featured a Centronics parallel port (not present on any CoCo), an integrated 6551A serial UART (on the Dragon 64), and a higher-quality keyboard. In 1983, a version of the Dragon was licensed for manufacture for the North American market by Tano Corporation of New Orleans, Louisiana. Tano started production at their 48,000-square-foot (4,500 m2) facility in September 83 and were running at capacity just one month later. Unfortunately sales weren't as good as expected and Tano stopped production and support just one year later.[4] A California surplus equipment company, California Digital, bought the remaining stock of Tano built Dragon 64 shortly after and has had new in-the-box Dragon 64s available for purchase as of December 2009.[5]
In Brazil, there existed several CoCo-clones, including the Prologica CP400 Color and CP400 Color II, the Varixx VC50, the LZ Color64, the Dynacom MX1600, the Codimex CD6809 and the "vaporware" Microdigital TKS800.
In Mexico, the Micro-SEP, a CoCo 2 clone with 64K of memory, was introduced by the Secretary of Education. The Micro-SEP was intended to be distributed nationally to all the public schools teaching the 7th to 9th grades. They were presented as a design of the Center of Advanced Research and Studies (CINVESTAV) of the National Polytechnic Institute (IPN).[6] Like the Dragon, these computers also included video output. Whether these computers were "designed" by this institute, or were licensed from the original design, is unclear.
A Taiwan-based company, Sampo, also made a CoCo clone, the Sampo Color Computer.[7] The Sampo was supposedly available in Taiwan, Korea, and possibly other Asian countries. It is believed that Tandy blocked sales in the US with legal action due to copyright infringements on the ROM code.
A cousin of the CoCo, The MC-10, or Micro Color Computer, was sold in Radio Shack stores as a lower cost, more entry-level computer than the CoCo. Released in 1983, it was similar in appearance to the Timex Sinclair. It also used the MC6847 VDG and Microsoft Basic, but featured the MC6803 instead of the 6809. It was just as bare-bones as the little Timex Sinclair model as well, lacking such things as an 80 column printer and disk storage system, as well as a "real" keyboard. Accordingly, it did not sell well and was withdrawn after just two years of production.[8] An MC-10 clone, the Sysdata Tcolor, was available in Brazil with 16 KB ROM.

Hardware design and integrated circuits

Internally the CoCo 1 and CoCo 2 models are functionally identical. The core of the system is virtually identical to the reference design included in the Motorola MC6883 data sheet and consists of five LSI chips:


The SAM is a multifunction device that performs the following functions:
  • Clock generation and synchronization for the 6809E MPU and 6847 VDG
  • Up to 64K Dynamic Random Access Memory (DRAM) control and refresh
  • Device selection based on MPU memory address to determine if the MPU access is to DRAM, ROM, PIA, etc.
  • Duplication of the VDG address counter to "feed" the VDG the data it is expecting
The SAM was designed to replace numerous small LS/TTL chips into one integrated package. Its main purpose is to control the DRAM but, as outlined above, it integrates several other functions as well. It is connected to a crystal at 4 times the television colorburst frequency (14.31818 MHz for NTSC countries). This is divided by 4 internally and is fed to the VDG for its own internal timing (3.579545 MHz for NTSC). The SAM also divides the master clock by 16 (or 8 in certain cases) for the two phase MPU clock; in NTSC this is .89 MHz (or 1.8 MHz if divided by 8).
Switching the SAM into 1.8 MHz operation gives the CPU the time ordinarily used by the VDG and refresh. As such, the display shows garbage; this mode was seldom used. However, an unusual mode available by the SAM is called the Address Dependent mode, where ROM reads (since they do not use the DRAM) occur at 1.8 MHz but regular RAM access occurs at .89 MHz. In effect, since the BASIC interpreter runs from ROM, putting the machine in this mode would nearly double the performance of a BASIC program while maintaining video display and DRAM refresh. Of course, this would throw off the software timing loops and I/O operations would be affected. Despite this, however, the "high speed POKE" was used by many CoCo BASIC programs even though it overclocked the hardware in the CoCo, which was only rated for 1 MHz operation.
The SAM has no connection to the MPU data bus. As such, it is programmed in a curious manner; its 16-bit configuration register is spread across 32 memory addresses (FFC0-FFDF). Writing even bytes sets that register bit to 0, Writing to odd bytes sets it to 1.
Due to limitations in 40-pin packaging, the SAM contains a duplicate of the VDG's internal 12-bit address counter. Normally this counter's settings are set to duplicate the VDG's display mode. However, this is not required and results in the creation of some new display modes not possible when the VDG is used in a system alone. Instead of the VDG requesting data from RAM by itself, the VDG is "fed" data by the SAM's internal copy of the VDG address counter. This process is called "Interleaved Direct Memory Access" (IDMA) by Motorola and ensures that the processor and VDG always have full access to this shared memory resource with no wait states or contention.
There are two versions of the SAM. The early one is labeled MC6883 and/or SN74LS783; the later version is labeled SN74LS785. There are some minor timing differences, but the major difference is the support of an 8-bit refresh counter in the 785 version. This allowed for use of inexpensive 16K by 4-bit and certain 64K by 1-bit DRAMs. Some third party bank-switching memory upgrades that used 256K DRAMs needed this 8-bit refresh counter to work.


Power-on screen of a CoCo 2
The MC6847 is a relatively simple display generator compared to the display chips of some of the CoCo's 8-bit rivals. It is capable of displaying text and graphics contained within a roughly square display matrix 256 pixels wide by 192 lines high. It is capable of displaying 9 colors: black, green, yellow, blue, red, buff (almost-but-not-quite white), cyan, magenta, and orange. The low display resolution is a necessity of using television sets as display monitors. Making the display wider risked cutting off characters due to overscan. Compressing more dots into the display window would easily exceed the resolution of the television and be useless, as the periphery of a textual screen would be unreadable.

Alphanumeric/Semigraphics display

Sample character set display of 6847 VDG
The CoCo is physically wired such that its default alphanumeric display is actually "Semigraphics 4" mode.
In alphanumeric mode, each character is a 5 dot wide by 7 dot high character in a box 8 dots wide and 12 lines high. This display mode consumes 512 bytes of memory and is a 32 character wide screen with 16 lines. The internal ROM character generator only holds 64 characters, so no lower case characters are provided. Lower case characters were rendered as upper case characters with inverted color. Although simulated screen shots would show this as green on black, on most CoCo generations it was actually green on very dark green.
Semigraphics is a hybrid display mode where alphanumerics and chunky block graphics can be mixed together on the same screen. If the 8th bit of the character is set, it is a semigraphics character. If cleared, it is an alphanumeric. When the 8th bit is set, the next three bits determine the color and last 4 bits determine which "quadrant" of the character box is either the selected color or black. This is the only mode where it is possible (without sneaky tricks) to display all 9 colors on the screen simultaneously. If used to only display semigraphics, the screen becomes a 64x32 9 color graphics mode. The CoCo features several BASIC commands to manage this screen as a low-res graphics display.
The alphanumeric display has two colorsets. The one used by default on the CoCo has black characters on a green background. The alternate has black characters on an orange background. The colorset selection does not affect semigraphics characters. The border in this mode is always black.
The 6847 is capable of a Semigraphics 6 display mode, where two bits select a color and 6 bits determine which 1/6 of the character box is lit. In this mode only 4 colors are possible but the Colorset bit of the VDG can select two different groups of the 4 colors. Due to a peculiarity of its hardware, only two colors are available in graphics blocks when using Semigraphics 6 on the CoCo.

Additional Semigraphics modes

By setting the SAM such that it believes it is displaying a full graphics mode, but leaving the VDG in Alphanumeric/Semigraphics 4 mode, it is possible to subdivide the character box into smaller pieces. This creates the "virtual" modes Semigraphics 8, 12, and 24.[9] In these modes it was possible to mix bits and pieces of different text characters as well as Semigraphics 4 characters. These modes were an interesting curiosity but not widely used, as the Semigraphics 24-screen consumed 6144 bytes of memory. These modes were not implemented on the CoCo 3.
A programmer's reference manual for the CoCo states that due to a fire at Tandy's research lab, the papers relating to the semigraphics modes were shuffled, and so some of the semigraphics modes were never documented. CoCo enthusiasts created experimental programs to try to reverse engineer the modes, and were able to reconstruct the missing documentation.[10][citation needed]

Graphics display

There were several full graphics display modes, which were divided into two categories: "resolution" graphics and "color" graphics. In resolution modes, each pixel is addressable as either on or off. There are two colorsets available, the first was black dots on a green background and green border, the second, more commonly used one has white dots on a black background with a white border. In color modes, each pixel was two bits, selecting one of four colors. Again the colorset input to the VDG determined which colors were used. The first colorset has a green border, and the colors green, yellow, red, and blue were available. The second colorset has a white border and the colors white, cyan, magenta and orange were available. Resolution graphics have 8 pixels per byte and are available in 128x64, 128x96, 128x192, and 256x192 densities. Color graphics have 4 pixels per byte and are available in 64x64, 128x64, 128x96, and 128x192 densities. The maximum size of a graphics screen is 6144 bytes.

Artifact colors

The 256x192 two color graphics mode uses four colors due to a quirk in the NTSC television system. It is not possible to reliably display 256 dots across the screen due to the limitations of the NTSC signal and the phase relationship between the VDG clock and colorburst frequency. In the first colorset, where green and black dots are available, alternating columns of green and black are not distinct and appear as a muddy green color. However, when one switches to the white and black colorset, instead of a muddy gray as expected, the result is either red or blue. Reversing the order of the alternating dots will give the opposite color. In effect this mode becomes a 128x192 4 color graphics mode where black, orange, blue, and white are available. Most CoCo games used this mode as the colors available are more useful than the ones provided in the hardware 4 color modes. Unfortunately the VDG internally can power up on either the rising or falling edge of the clock, so the bit patterns that represent orange and blue are not predictable. Most CoCo games would start up with a title screen and invited the user to press the reset button until the colors were correct. The CoCo 3 fixed the clock-edge problem so it was always the same; a user would hold the F1 key during reset to choose the other color set. On a CoCo 3 with an analog RGB monitor, the black and white dot patterns do not artifact; to see them one would have to use a TV or composite monitor, or patch the games to use the hardware 128x192 four color mode in which the GIME chip allows the color choices to be mapped. Users in PAL countries saw green and purple stripes instead of solid red and blue colors.
Readers of The Rainbow or Hot CoCo magazine learned that they could use some POKE commands to switch the 6847 VDG into one of the artifact modes, while Extended Color Basic continued to operate as though it were still displaying one of the 128x192 four-color modes. Thus, the entire set of Extended Color Basic graphics commands could be used with the artifact colors. Some users went on to develop a set of 16 artifact colors using a 4x2 pixel matrix, giving this set of colors: black, dark cyan, brick red, light violet, dark blue, azure (the blue above), olive green, brown, purple, light blue, orange, yellow, light gray, blue-white, flesh, and white. Use of POKE commands also made these colors available to the graphics commands, although the colors had to be drawn one horizontal line at a time. Some interesting artworks were produced from these effects, especially since the CoCo Max art package provided them in its palette of colors.

Lower case and the 6847T1

Sample character set display of 6847T1 VDG in true lower case mode
The 6847 is capable of using an external character generator. Several third party add-on adapter boards would allow the CoCo to display real lowercase characters.
Very late in the CoCo 2 production run, an enhanced VDG was available. Called the 6847T1, it included a lower case character generator and the ability to display a green/orange or black border on the text screen. Its other changes were mainly to reduce parts count by incorporating an internal data latch. The lower case capability of this VDG is not enabled by default on this system and is not even mentioned in the manual. Only through some tinkering and research was this feature discovered by intrepid CoCo users.
The 6847T1 may also carry the part number XC80652P; these may have been pre-release parts.


There are two PIA chips in all CoCo models. The PIAs are dedicated mainly to I/O operations such as driving the internal 6-bit Digital-to-analog converter (DAC), reading the status of the DAC's voltage comparator, controlling the relay for the cassette motor, reading the keyboard matrix, controlling the VDG mode control pins, reading and writing to the RS232 serial I/O port, and controlling the internal analog multiplexers.
The earliest CoCo models had two standard 6821 chips. Later, due to changes in the keyboard design, it was found that the 6822 IIA (industrial interface adapter) was better suited to the keyboard's impedance. The 6822 was eventually discontinued by Motorola but was produced for Tandy as an ASIC with a special Tandy part number, SC67331P. Functionally the 6821 and 6822 are identical and one can put a 6821 in place of the 6822 if that part is bad. Some external pull-up resistors may be needed to use a 6821 to replace a 6822 in a CoCo for normal keyboard operation.

Interface to external peripherals

Due to the CoCo's design, the MPU encounters no wait states in normal operation. This means that precise software controlled timing loops are easily implemented. This is important, since the CoCo has no specialized hardware for any I/O. All I/O operations, such as cassette reading and writing, serial I/O, scanning the keyboard, and reading the position of the joysticks, must be done entirely in software. This reduces hardware cost, but reduces system performance as the MPU is unavailable during these operations.
As an example, the CoCo cassette interface is perhaps one of the fastest available (1500-bit/s) but it does so by literally playing software generated sine waves through its internal 6-bit DAC. While this is happening, the CoCo cannot do anything else as this uses all the CPU time. Similarly, to read data off the cassette, the CoCo must count waveform crossings and thus cannot do anything else until either an error occurs or the operation ends.
The precise timing loops made the CoCo useful for laboratory purposes. Since it has no operating system servicing interrupts, it can do precisely timed read-modify write operations for scientific instrumentation, at a speed that cannot be matched by even the newest Windows computers without disabling the Windows operating system.

CoCo 3 hardware changes

The hardware in the CoCo 1 and CoCo 2 models was functionally the same; the only differences were in packaging and integration of some functions into small ASICs. The CoCo 3 radically changed this. A new VLSI ASIC, called (officially) the Advanced Color Video Chip (ACVC) or (unofficially) the Graphics Interrupt Memory Enhancer (GIME), integrated the functions of the SAM and VDG while enhancing the capabilities of both. Aside from the graphics enhancements outlined above, the CoCo 3 offered true lower case, 40 and 80 column text display capability, and the ability to run at 1.8 MHz without loss of video display. As such the processor was changed to the 68B09E and the PIA was changed to the 68B21, which are 2 MHz rated parts.


The CoCo's main competition was from the Commodore VIC-20, Commodore 64, Apple II, and the Atari 400 and Atari 800.
While the CoCo sported perhaps the most advanced 8-bit processor ever made, that processing power came at a significant price premium. In order to sell the CoCo at a competitive price, its relatively expensive processor was not tied to any specialized video or sound hardware. In comparison, the 6502-derived processor in the Commodore, Apple and Atari systems was much less expensive. Both Commodore and Atari had invested in advanced graphics and sound chip design for arcade games and home gaming consoles. By tying these specialized circuits with an inexpensive processor, Atari and Commodore systems were able to play sophisticated games with high quality graphics and sound. The trade-off is between a system with an expensive CPU that does a lot of work, or an inexpensive CPU that controls the registers of its sound and video hardware.
The CoCo video hardware was derived from a chip designed as display for a character based terminal, and is a completely "dumb" device. Similarly, the sound hardware is little more than a 6-bit DAC under software control. All graphics and sound require direct CPU intervention, and while this allows for great flexibility, its performance is much lower than dedicated hardware.
Games drove system sales then as they do now, and with its poor gaming performance, the CoCo attracted little interest in officially licensed ports of popular games. The CoCo 3 did improve graphics capability and doubled CPU performance, but still contained no hardware graphics or sound acceleration. Drawing was performed by the CPU, and most of the new graphics modes required at least twice as much processor time due to increased display resolution and color depth. The sound hardware was not changed at all.
Every computer platform is a compromise, and despite the significant graphics and sound handicap the CoCo may have had, it still had a sophisticated CPU under its hood with extremely high performance. There were many independent clones of popular games available, but far more important was the availability of "killer apps" for the CoCo. For instance, CoCo-Max and Max-10 were clones of MacPaint and MacWrite. The OS-9 operating system, a UNIX-like multi-tasking multi-user environment, was also available. Even the BASIC interpreter was one of the most powerful available, and provided the user with a rich set of easy-to-use commands for manipulating on-screen graphics and playing sounds.
Some of the hardware limitations were overcome with external add-ons, particularly expansion cartridges. Some were made by Tandy, some by other manufacturers. Examples are:
  • RS232 Program Pak, which provided a real RS232 UART for serial communications (the 6551A)
  • The Speech & Sound Pak, which provided a speech synthesizer and a sound generator chip
  • Word-Pak and Word-Pak II 80 column display adapters produced by PBJ, Inc. allowed connection to an external monochrome monitor (not needed for CoCo 3).
  • 300 baud modem pak
  • Advanced floppy and hard drive controllers (mostly for OS-9)
Key to taking advantage of these expansion capabilities is the Multi-Pak interface, which permits up to four devices such as these to be attached to the system at the same time.

The OS-9 divide

There is/was a major division of CoCo users: those who used OS-9 and those who used Disk Extended Color BASIC (DECB). The divide comes from the fact that programs using DECB (except for those that used CoCo's form of BASIC) used DECB only as a loader and for disk I/O, communicating with the hardware directly for all other activities. OS-9 applications communicate with OS-9 and its drivers. This allows for a degree of hardware independence.
Many programs written for the CoCo were DECB programs. In order to support such programs (or at least, those that bypassed BASIC and addressed hardware directly), any future CoCo version would have to be hardware-compatible with the CoCo, or perfectly emulate every aspect of the CoCo. In contrast, OS-9 programs relied only on OS-9 functions, and its drivers could be rewritten to work with different hardware. However, DECB comes with the CoCo system itself, and required no further setup or purchasing. OS-9 was an additional product that had to be loaded manually each time the computer was started. Writing an OS-9 program meant appealing to a smaller subset of the CoCo community; this discouraged development of OS-9 products.

The end of the road

On October 26, 1990, Ed Juge of Tandy announced that the CoCo 3 would be dropped from its computer line. With no apparent successor mentioned, the announcement was disheartening to many loyal CoCo fans.
Even today, current and former CoCo owners agree[weasel words] that Tandy did not take the CoCo very seriously, despite it having been their best-selling computer for several years.[citation needed] Tandy failed to market the CoCo as the powerful and useful machine that it was, and offered customers no hint about the large number of third party software and hardware products available for it.[citation needed]
The release of the CoCo 3 was particularly lackluster despite its greatly enhanced graphic capabilities and RGB monitor support. Radio Shack fliers and stores typically depicted the CoCo 3 running CoCo 2 games, and offered a very limited selection of CoCo 3 specific software. There was an official Radio Shack store demo,[11] but few stores bothered to run it.[citation needed]
Additionally, DRAM prices skyrocketed at the time the CoCo 3 was released, making the 512K memory upgrade considerably more expensive than the 128K CoCo 3 itself. Very few stores displayed a 512K machine or a CoCo 3 running such games as King's Quest or Leisure Suit Larry.[citation needed]
Lonnie Falk, of The Rainbow, announced at the 1991 CoCo Fest convention that the reason Tandy decided to drop the Color Computer line was that a third party vendor sold a simple adaptor cable that let the Color Computer play Nintendo game cartridges, and that Nintendo had threatened to sue Tandy.


In spite of Tandy's apparent lack of concern for the CoCo market, there were rumors of the existence of a prototype CoCo 4 at Tandy's Fort Worth headquarters. Several first hand accounts of the prototype came from people like Mark Siegel of Tandy and Ken Kaplan of Microware, yet there exists no known physical evidence of such a machine.
A few independent companies attempted to carry the CoCo torch, but the lack of decent backwards compatibility with the CoCo 3 failed to entice much of the CoCo community over to these new independent platforms. Many of these independent platforms did run OS9/68k, which was very similar to OS-9. However the bulk of the CoCo community moved on to more mainstream platforms. Some CoCo users swore their loyalty to Motorola and moved on to the Amiga, Atari ST, or even the Macintosh, all of which were based on the Motorola 68000 processor. Others jumped to the IBM PC-compatible.


Frank Hogg Labs introduced the Tomcat TC-9 in June 1990, which was somewhat compatible with the CoCo 3, but was mostly only able to run OS-9 software. A later version called the TC-70 (running on a Signetics 68070) had strong compatibility with the MM/1, and also ran OS-9/68K.


The Multi-Media One was introduced in July 1990, ran OS-9/68K on a 15 MHz Signetics 68070 processor with 3 MB RAM, and had a 640x208 graphics resolution as well as supporting a 640x416 interlaced mode. It included a SCSI interface, stereo A/D and D/A conversion, an optional MIDI interface, and (later) an optional board to upgrade the CPU to a Motorola 68340 running at up to 25 MHz. It is estimated that about 500 units were sold.[citation needed]


The AT306 (also known as the MM/1B) was a successor to the MM/1 that contained a Motorola 68306 CPU, OS-9/68K 3.0, and was designed to allow the use of ISA bus cards. It was created by Kevin Pease and Carl Kreider, and sold by Carl's company, Kreider Electronics. It was also sold as the "WCP-306" by Bill Wittman of Wittman Computer Products.

Delmar System IV/Peripheral Technology PT68K-4

Peripheral Technology produced a 16 MHz Motorola 68000 system called a PTK68K-4, which was sold as a kit or a complete motherboard. Delmar sold complete systems based on the PT68K-4 and called the Delmar System IV. The PT68K-4 has the footprint of an IBM PC, so it will fit in a normal PC case, and it has seven 8-bit ISA slots. Video was provided by a standard IBM style monochrome, CGA, EGA, or VGA video card and monitor, but for high resolution graphics the software only supported certain ET4000 video cards. It appears that most users of this system used/uses OS-9, but there are several operating systems for it, including REX (a FLEX-like OS), and SK*DOS. Dan Farnsworth, who wrote REX, also wrote a BASIC interpreter that was fairly compatible to DECB, but it was too little, too late to be of interest to many CoCo users. There was also a card available called an ALT86, which was basically an IBM XT compatible computer on a card, which allowed the user to run DOS programs on it. In fact, both the 68000 and the ALT86 card could be run at the same time, if access to the ISA bus was not needed from the 68000 side of it.

The 21st century

The CoCo still has a small but active user community despite a perceived lack of support from Tandy. Third-party support was assisted by CoCo-related periodicals, notably The Rainbow, Hot CoCo, and The Color Computer Magazine. Original hardware is being expanded by some small firms such as Cloud-9 with such things as SCSI and IDE hard drive controllers, memory upgrades to 512K and AT Keyboard interfaces. Other recent hardware development includes RGB-to-VGA Converter[12] that allows connecting a Coco3 to a standard VGA compatible monitor.
User-driven support for the Color Computer has continued since production stopped in the '80s, hosted on various web sites and forums.


Emulation of the CoCo hardware has been possible on x86 PCs since at least the mid '90s. MESS is capable of emulating the CoCo. Other emulators include VCC (see external links), Jeff Vavasour's CoCo emulators (see external links) and Mocha, a web-based emulator written in Java that can emulate a CoCo 2 inside a web browser (see external links).
Most of these emulators require a dump from the CoCo ROMs. Instructions are usually provided with the emulators on how to get a ROM dump from a CoCo. A ROM might be found online, which may be from a Brazilian CoCo clone.
Utilities exist to transfer data from a PC to a CoCo. If one does not have compatible disk drives for the PC and CoCo, data may still be transferred by using special PC CoCo utilities to create a .wav audio file of the data. Hook the CoCo's cassette interface cables directly to the line out of a PC's soundcard, initiate the CLOAD (or CLOADM) command on the CoCo, and then play the sound file from the PC.

See also


  1. ^ Feb. 1986 BYTE Magazine, JDR Microdevices Ad, pg. 448
  2. ^ Nickolas Marente. "In Search of 256". Retrieved 2008-06-11.
  3. ^ "NitrOS-9 operating system for the Tandy/Radio Shack Color Computer". Retrieved 2008-06-11.
  4. ^ Dragon Archive History <>
  5. ^
  6. ^ "Red Escolar y el modelo de uso de las Tecnologías de la Información y la Comunicación en Educación" (in Spanish). 4º Encuentro Nacional de Red Escolar. October 16, 2006. Retrieved 2008-06-11.[dead link]
  7. ^ Nov. 1982 BYTE Magazine ad
  8. ^ 1984 Tandy Catalog RSC 11 was the last to have the MC-10 <>
  9. ^ Chris Lomont's Color Computer 1/2/3 Hardware Programming
  10. ^ Semigraphics24 for the Coco1&2. Machine language program to create 8 true colors plus text on screen at one time.
  11. ^ L. Curtis Boyle (April 19, 2006). "Official Radio Shack Coco 3 Demo". NitrOS9.LCURTISBOYLE.COM. Retrieved 2008-06-11.
  12. ^ Coco3 RGB-to-VGA Converter

External links

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TRS-80 Model 100

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TRS-80 Model 100
Developer Kyocera, Tandy, Microsoft
Type Portable computer
Release date 1983
Introductory price US$1099 for 8K version
US$1399 for 24K versions
Units sold 6,000,000
Operating system Custom dedicated runtime in firmware
Power Four penlight (AA) cells, or external power adapter 6V (>180 mA)
CPU Intel 80C85 @ 2.4 MHz
Memory KB - 32 KB (supported)
Display 8 lines, 40 characters LCD
Graphics 240 by 64 pixel addressable graphics
Input Keyboard:56 keys, 8 programmable function keys, and 4 dedicated command keys
Dimensions 300 by 215 x 50 mm
Weight About 1.4 kilograms (3.1 lb) with batteries
The TRS-80 Model 100 was an early portable computer introduced in 1983. It was one of the first notebook-style computers, featuring a keyboard and liquid crystal display, battery powered, in a package roughly the size and shape of notepad or large book.
It was made by Kyocera, and originally sold in Japan as the Kyotronic 85. Although a slow seller for Kyocera, the rights to the machine were purchased by Tandy Corporation, and the computer was sold through Radio Shack stores in the United States and Canada as well as affiliated dealers in other countries, becoming one of the company's most popular models, with over 6,000,000 units sold worldwide. The Olivetti M-10 and the NEC PC-8201 and PC-8300 were also built on the same Kyocera platform, with some design and hardware differences. It was originally marketed as a Micro Executive Work Station (MEWS), although the term did not catch on and was eventually dropped.



The internals of the TRS-80 Model 100. The left half is the back.
  • Processor: 8-bit Intel 80C85, CMOS, 2.4 MHz
  • Memory: 32 kB ROM, 8, 16, 24, or 32kB static RAM. Machines with less than 32 kB could be expanded in 8 kB increments of plug-in static RAM modules.
  • Display: 8 lines, 40 characters LCD with 240 by 64 pixel addressable graphics. The screen was not backlit.
  • Keyboard: 56 keys, 8 programmable function keys, and 4 dedicated command keys.
  • Peripherals: The basic package included: Built-in 300 baud modem (North American versions), parallel printer port, serial communication port (shared by internal modem), bar-code reader input, cassette audio tape, real-time clock.
  • Dimensions: 300 by 215 x 50 mm, weight about 1.4 kilograms (3.1 lb) with batteries
Power supply: Four penlight (AA) cells, or external power adapter 6V (>180 mA, tip negative configuration)
The 8K and 24K versions sold for US$1099 and US$1399 respectively.[1]
The Model 100 was promoted as being able to run up to 20 hours and maintain memory up to 30 days on a set of four alkaline AA batteries.
The Tandy Portable Disk Drive (TPDD), a serial device capable of storing 100 KB of data on a 3.5 inch diskette was also available. A second version, the TPDD2, could store up to 200 KB, as it used double sided disks.
A disk-video interface expansion box was released in 1984, with 5-1/4 inch disk drives and a CRT video adapter. This allowed the Model 100 to display 40 or 80 column video on an external television set or video monitor.
A bar code reader wand was also offered.

ROM firmware

When first switched on, the Model 100 displays a menu of applications and files and the date and time. The ROM firmware based system boots instantly, which compares very favourably to disk-based computers. Not only is the machine ready to use immediately on power-up, but it will also continue running, from the same point, the program that was running when the unit was powered off. Cursor keys are used to navigate the menu and select one of the internal or added application programs, or any data file to be worked upon.
The 32 kilobyte read-only memory of the Model 100 contains the N82 version of the Microsoft BASIC 80 programming language. This is similar to other Microsoft BASICs of the time and includes good support for the hardware features of the machine: pixel addressing of the display, support for the internal modem and serial port, monophonic sound, access to tape files, and support for the real-time clock and the bar code reader. Unlike other Microsoft BASIC interpreters of the time, the default for floating point numbers is double-precision.
The ROM also contains a terminal program, TELCOM; an address/phone book organizer, ADDRSS; a to-do list organizer, SCHEDL; and a simple text editor, TEXT. The TELCOM program allows automation of a login sequence to a remote system under control of the BASIC interpreter.
As with other home computers of the era, a vast collection of PEEK and POKE locations were collected by avid hobbyists.
Invisible files in the system RAM named "Hayashi" and "Suzuki" commemorate the names of designers Junji Hayashi and Jay Suzuki. Another invisible deleted file named "RickY" refers to Rick Yamashita.[2] The Model 100 firmware was the last Microsoft product that Bill Gates developed personally, along with Suzuki. According to Gates, "part of my nostalgia about this machine is this was the last machine where I wrote a very high percentage of the code in the product".[3]
Added applications and data files are stored in the internal battery-backed RAM; these can be loaded from and stored to an audio cassette tape recorder or external floppy disk drive. Optional ROMs can be installed in the Model 100, providing a range of customized application software.
The Model 100 ROM has a Y2K bug; the century displayed on the main menu was hard-coded as "19XX". Workarounds exist for this problem.


When introduced, the portability and simplicity of the Model 100 made it attractive to journalists,[4] who could type about 11 pages of text and then transmit it using the built-in modem and TELCOM program for electronic editing and production. The computer is silent when it operates. The keyboard is full-size and uses a standard (QWERTY) layout. It runs for 20 hours on 4 readily available and easily replaceable AA batteries. Data is protected by a built-in rechargeable battery. There is no boot up routine; the Model 100 operates as soon as the switch is flipped and an application selected. There are several simple programs available on the Internet for transferring Model 100 files to a modern personal computer.
The Model 100 was also used in industrial applications as a programming terminal for configuration of control systems and instruments.
Third-party peripherals for the Model 100 extended its battery life and file storage capacity. Software was designed, and is still available, to extend the display capabilities and to provide more advanced word-processing or calculation software than the supplied programs. To this day, hobbyists continue to design games, applications, and hardware for this device.
Modern portable computers (laptops) are larger, heavier, and have much shorter battery life than the Model 100. The closest modern successors include the Alphasmart Dana and the Quickpad Pro. These similar modern "slabtop" units typically are targeted at the education market, although they are often used by writers and mobile professionals.
Although much larger, the Model 100 actually bears a close resemblance to modern PDAs. Its TEXT program is similar to the Memo program found on PalmOne products, and ADDRSS and SCHEDL are essentially simplified versions of Contacts, Tasks and Calendar. The Model 100 has the additional advantage of a full size keyboard, a built-in modem and BASIC programming language. By including BASIC, the Model 100's designers made it possible for users to design additional applications.
Because of its adaptability and features as well as its current relative affordability, the Model 100 and its progeny (Model 102/200/600) enjoy a near cult status among its supporters. Club 100 and Bitchin100 are the center of the Model 100 universe. Model 100 enthusiasts continue to explore this early computer, trading information, participating in contests and designing new applications with existing and newly designed hardware and software.

Peers and successors

A Tandy 200, shown next to a 21st century Windows-based laptop
The Tandy 200 was introduced in 1984 as a more capable sister product of the Model 100. The Tandy 200 had a flip-up 16 line by 40 column display, and came with 24 KB RAM which could be expanded to 72 KB (3 banks of 24 KB). It included Multiplan, a spreadsheet application. It also added DTMF tone dialing for the internal modem, where the Model 100 only supported pulse dialing.
The last new model that could be considered part of this line was the Tandy 600, introduced in October 1985. Similar to the Tandy 200, it featured a flip-up screen, but with 80 columns rather than 40. Built-in features included a 3.5" diskette drive, rechargeable batteries, and 32K of RAM expandable to 224K. The underlying software platform was Microsoft's 16-bit Hand Held Operating System (Handheld DOS or HHDOS), along with word processing, calendar, database, communication and spreadsheet software. Unlike earlier models, BASIC was an extra-cost option rather than built in.[5]
The last refresh to the product line was the Tandy 102, introduced in 1986 as a direct replacement for the Model 100, having the same software, keyboard and screen, and a nearly identical, but thinner, form factor. Minimum memory was 24 KB RAM.
Later portables from Tandy no longer featured a ROM-based software environment, starting with the Tandy LT1400, which ran a diskette-based MS-DOS operating system.

Similar computers from other companies

The NEC PC-8201 computer
As mentioned previously, the Olivetti M-10 and the NEC PC-8201 and PC-8300 were also built on the same platform as the original Kyocera design. The earlier and smaller Epson HX-20 of 1983 used a much smaller LCD display, four lines of twenty characters, and had an internal cassette tape drive for program and file storage. There were several other "calculator-style" laptops available at the time, including the Casio FP-200, the Texas Instruments CC-40, and the Canon X-07.[6]
Systems of about the same size and form-factor as the Model 100, aimed at journalists, were sold by companies such as Teleram, as the Teleram T-3000[7] and GRiD Systems, as the GRiD Compass, which was used by NASA. GRiD was later acquired by Tandy. The Bondwell 2 of 1985 was a CP/M laptop in a similar form factor to the Model 200.
Data General developed the Data General-One (DG-1), a much more powerful (but more costly) MS-DOS portable computer with disk drives and a full-sized LCD screen, similar to the Tandy LT1400. It was released in 1984. The Zenith ZP-150, also of 1984, was introduced prior to the Tandy 600. The two computers were notably similar, although the ZP-150 did include BASIC and could be configured with more memory, but did not have a built-in diskette drive.
The Cambridge Z88 of 1987, developed by British inventor Sir Clive Sinclair, was similar in form and functionality to the Model 100 but had greater expansion capacity.


  • VirtualT An open source Model 100/102/200 emulator with an integrated debugger, hardware access utilities and a complete FX-80 printer emulation.

Aftermarket products

  • DLPilot - allows a PalmOS PDA with a serial port to emulate a Tandy TPDD drive, providing affordable, compact, and portable storage that is easily synced to a desktop computer
  • ReMem - replaces all the memory in the laptop, allowing the use of 4MB of flash ROM and 2MB of SRAM
  • REX - memory subsystem that fits in the option ROM socket
  • Tandy 200 RAM Module - adds 2 banks of 24kb to a T200
  • NADSBox - New Age Digital Storage Box - Interfaces an SD media card using the Tandy TPDD drive protocol for portable storage and easy file transfers to a desktop computer using industry standard FAT formatted Secure Digital cards.
  • PCSG's SupeROM - WriteROM word processor; FORM spreadsheet input template; LUCID spreadsheet; Database (relational); Thought outliner.


  1. ^ "The Micro Executive Workstation(TM)". Radio Shack 1984 Catalog. Tandy Corporation. 1984. pp. 59. Retrieved 2008-01-08.
  2. ^ Akira Kogawa (October 28, 2005). "The Bill Gates I Know, Volume 12" (in Japanese). Retrieved 2008-01-08. Title and author obtained via Google translation from the original Japanese.
  3. ^ Gates, Bill. Interview with Bill Gates. with David Allison. Transcript of a Video History Interview by the National Museum of American History, Smithsonian Institution. Retrieved 2008-01-08.
  4. ^ Bruce Garrison Computer-assisted reporting, Routledge, 1998 ISBN 0-8058-3021-9 , page 192
  5. ^ "The Tandy 600 FAQ - Version 3". DigitalDinos. May 26, 2008. Retrieved 2009-02-22.
  6. ^ 14 notebook computers in brief: Creative Computing Vol 10 No 1, January 1984
  7. ^ The Portable Companion, June/July 1982
  • TRS-80 Model 100 Owner's Manual, (1983) Tandy Corporation, Fort Worth Texas
  • BYTE Magazine April 1984, advertisement for Disk-Video Interface
  • BYTE Magazine May 1985, advertisement for Model 200
  • Rich Malloy, "Little Big Computer: The TRS 80 Model 100 Portable Computer", BYTE magazine, May 1983 pg. 14
  • Stan Wszola, "NEC PC 8201 Portable Computer", BYTE magazine June 1983, pg. 282

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  (Redirected from Tandy Deskmate)
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Developer(s) Tandy
Stable release 3.05 / c.1992
Operating system Microsoft MS-DOS
Type GUI
License Proprietary
DeskMate was a software application that provided an operating environment that competed with early versions of Microsoft Windows. It originally was made for Tandy's TRS-DOS Operating System and for their TRS-80 line of computers, but eventually shifted to PC, where it was developed using C and Assembly. Like Windows (and other competitors from the time, such as GEM), it was not a full operating system, requiring a separate Disk operating system in order to function. Although the initial PC ports would only run on Tandy's PCs (such as the Tandy 1000), the introduction of the true PC-compatible computers such as the Tandy 3000 resulted in the software later being made available for other compatibles.


DeskMate 1.0

DeskMate version 1.0 was included with the original Tandy 1000 and did not work correctly on non-Tandy computers. This was mainly due to the use of the function keys - as most non-Tandy PCs either did not come with an F12 button or with one that did not act in the same way as a Tandy F12 function key.

DeskMate 2

By the time Personal DeskMate was released with the Tandy 1000 EX, it was a GUI that acted as a portal for many other office productivity applications. The DeskMate application would run on top of MS-DOS. The user interface was made up of text. The applications that made up the suite were:
  • a basic word processor ("Text")
  • a spreadsheet ("Worksheet")
  • a calendar
  • a basic database program ("Filer")
The programs all fit on a 360K floppy disk. With careful manipulation, it was possible to isolate the individual applications and remove the others, placing them on separate floppies to be swapped when required. DeskMate was still required, as the individual programs could not be accessed directly.

DeskMate 3

DeskMate 3 added a number of interesting basic applications:
  • a drawing program ("Draw")
  • a simple digital audio editing program ("Sound")
  • a simple music program ("Music"), which could play music with audio samples created in Sound, used the 3-channel Tandy DAC, which provided 22kHz 8-bit audio.
  • an online service ("PC Link")
The core parts of DeskMate (and DOS) were shipped in ROM on certain Tandy 1000s, allowing the computer to boot into DeskMate within a few seconds.
This was the first version of DeskMate that allowed for a run-time version that could be distributed with applications. This allowed users to use DeskMate applications on their PC's even if they did not have DeskMate installed.


This was a complete rewrite for Microsoft Windows 3.1, providing a simplified user interface and a few applications.

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Tandy Corporation

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Tandy Corporation
Industry Retail
Fate became Radio Shack Corporation
Founded 1919
Defunct 2000
Headquarters Fort Worth, Texas, USA
Products Leather
Website none
Tandy Corporation was a family-owned leather goods company based in Fort Worth, Texas. Tandy was founded in 1919 as a leather supply store, and acquired RadioShack in 1963. The Tandy name was dropped in May 2000, when RadioShack Corporation was made the official name.



Tandy began in 1919 when two friends, Norton Hinckley and Dave L. Tandy, decided to start the Hinckley-Tandy Leather Company, which sold leather shoe parts to shoe repair shops in the Fort Worth area. Tandy's son, Charles D. Tandy, turned it into a leathercraft company when shoe rationing in World War II almost killed the business, and later expanded into selling leather and tools to make such products as wallets. After a struggle over the company, which saw the Hinckley name dropped, Tandy made another change in 1963, when it bought the ailing RadioShack. It later sold off all non-electronic business. The leather business continued, and eventually combined with The Leather Factory in 2000 to become Tandy Leather Factory.[1]


A Tandy laptop computer, the 1400LT
Tandy was one of the companies (along with Commodore International, Atari, and Apple) that started the personal computer revolution in the USA, with their TRS-80 (1977) and TRS-80 Color Computer ("CoCo") (1980) line of home computers. Later Tandy adopted the IBM PC architecture. Tandy's IBM PC compatibles, the Tandy 1000 and Tandy 2000, were cheaper than the IBM PC and yet featured built-in, and better, sound and graphics. These machines could produce 16-color video and operated two dynamic sine/square/sawtooth sound channels: a non-dynamic sound channel and a dynamic white/pink/brown noise channel. It was only when VGA-standard graphics cards and Sound Blaster sound cards became common in the early 1990s that the Tandy's advanced features became noncompetitive and thus obsolete.
Tandy acquired GRiD Systems in March 1988.[2] Grid Systems was a laptop manufacturer whose products included the GRiD Compass (1982), GridCase (1985), GridLite (1987), and GRiDPad (1990) tablet computer.
Tandy also produced short lived Tandy 1100FD and Tandy 1100HD notebooks. Released in 1989, the 1100 Series was based on the popular NEC V20 processor clocked at 8 MHz. Tandy also produced software for its computers running DOS, in the form of Tandy Deskmate.[3] That same year, Tandy introduced the WP-2, a solid state notebook computer that was a rebadged Citizen CBM-10WP. Eventually, in the early 1990s, Tandy Corporation sold its computer manufacturing business to AST Computers,[4] and all Tandy computer lines were terminated. When that occurred, Radio Shack stores began selling computers made by other manufacturers, such as Compaq. In 1992, the company introduced the Tandy Zoomer, a predecessor to the Palm Pilot, designed by Jeff Hawkins. Also that year, the company produced an interactive, multimedia CD-ROM player called the Tandy Video Information System (VIS). Like the Tandy computers, it was based on the IBM PC architecture and used a version of Microsoft Windows. Tandy even produced a line of floppy disks, and continued producing IBM PC compatibles until the end of the Intel 486 era.

Tandy stores

Tandy Logo used in the UK
In 1973 Tandy Corporation began an expansion program outside their home market of the USA opening a chain of RadioShack-style stores in Europe and Australia under the Tandy name. The first store to open was in Aartselaar Belgium August 9, 1973. Initially these new stores were under direct ownership of Tandy Corporation. In 1986 Tandy Corporation formed its subsidiary InterTAN as separate entity though connections between them were still visible. For example, catalog number compatibility was maintained, so the same catalog number in both companies would refer to the same item.
In 1999 the UK stores were sold to Carphone Warehouse, and over the following years have either been closed, or turned into Carphone Warehouse stores. Some of these stores were sold to a new company called T2 which continued the RadioShack style theme. Lately, many of these stores have closed down, though T2 has a strong presence online and has a wide range of RadioShack products.
In 2001 the Australian stores were sold to Dick Smith Electronics (DSE), a subsidiary of Woolworths Limited. Most Australian Tandy stores have been closed or rebranded as Dick Smith, and only four Tandy stores remained as of June 2011.[1]
In Canada, the InterTAN stores were sold to rival Circuit City Inc. At that time, the stores were branded as RadioShack, however, because Circuit City lost the naming rights, all RadioShacks were re-branded as "The Source by Circuit City" (now called just The Source.) Some have closed.

Other retail outlets

McDuff Electronics, VideoConcepts

In 1985, Tandy acquired two chains, McDuff Electronics and VideoConcepts. Most of these stores were closed as part of a 1994 restructuring plan, with 33 converted to RadioShack or Computer City Express stores.[5] Remaining McDuff stores were closed in 1996.[6]

The Edge in Electronics

The Edge in Electronics, a now-defunct chain of boutique stores geared toward mall customers interested in fashionable personal and portable name brand electronics, debuted in 1990 and had 16 stores as of December 1993. One of the last stores open closed its doors in San Antonio TX in 2001.

Incredible Universe

The Incredible Universe concept was Tandy's attempt to compete with other electronics giants such as Best Buy and Circuit City; the first two stores, located in Arlington, Texas and Wilsonville, Oregon, opened in 1992. Each Incredible Universe store stocked more than 85,000 items, and the stores' sales personnel did not work on commission. Sales were below average compared to Tandy's profitable RadioShack line, and by late 1996, the company had decided to sell or close all 17 Incredible Universe stores.[7] Many Incredible Universe stores were acquired by Fry's Electronics.

Computer City

Computer City was a supercenter concept featuring name-brand computers, software and related products; by the end of 1993, Tandy had 40 locations, including three in Europe. The Computer City stores were later sold to CompUSA.

O'Sullivan Industries

In 1983, Conroy sold O'Sullivan Industries to Tandy Corporation. In 1994, Tandy Corporation offered O'Sullivan as a public company. In 1999 O'Sullivan was purchased for about $350 million by investment group OSI Acquisition, an affiliate of Brockman, Rosser, Sherrill & Co., L.P. (BRS).

Coppercraft Guild

In 1973, Tandy launched a subsidiary company called Coppercraft Guild, which sold solid copper knicknacks and housewares through a network marketing channel. Most notable were the "Franklin Cups" which were based on a design by Benjamin Franklin, sold in packs of six. The products were attractive and well designed, but the product line folded after about five years. Coppercraft Guild items are still popular with collectors on eBay.

See also


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Radio Shack Tandy TRS-80 was Tandy Corporation's desktop microcomputer model line, sold through Tandy's Radio Shack stores in the late 1970s and early 1980s, and one of the earliest mass-produced personal computers

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