Color Computer I

Introduced on July 31st, 1980 for $399.00
Motorola MC6809E 8-bit CPU running at .89MHz
8K ROM - Microsoft Color Basic v1.0
53 Key Keyboard
32 Column Display Ability
RGB Modulator (to connect to color TV)
RS-232 Interface (Serial Port)
1500 Baud Cassette Interface
Joystick Connectors
Optional: ROM-PAK Cartrdige
(Chess, Checkers, Quasar Commander, Personal Finance, CoCo Diagnostics)
Optional (12/1980): 16K RAM Upgrade
Optional: 32K RAM Upgrade
Optional: 64K RAM Upgrade
Optional (12/1980): 16K RAM Upgrade
Optional (07/1981): Extended Color Basic Upgrade

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, some models shipped in a white case with a modified keyboard, often referred to as the "melted" keyboard, which had bigger keycaps but a similar rubbery feel. At about the same time, another white-cased "CoCo", 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 completely identical to the CoCo 1. The TDP-100 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.

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.


Color Computer 2

Same as the Color Computer I except
Smaller Case

Extended Color Basic

16k RAM - 64k RAM
Typewriter Keyboard

on later models...Lowercase Letters

OS-9 Level I multi-tasking operating system

Optional Equipment: MultiPack Interface
Optional Equipment: 5.25" floppy drive

Production was  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.

Color Computer 3

Introduced on July 30th, 1986 for $219.95
Motorola MC6809 8-bit CPU running at 2MHz
128K RAM (Upgradable to 512K)
640X200 resolution and 64 colors
80 Column Display Ability
4 analog inputs and 1 analog output
Digital Input and Output
OS-9 Level II multi-tasking operating system
Optional Equipment: MultiPack Interface
Optional Equipment: 5.25" floppy drive

On July 30, 1986, Tandy announced the Color Computer 3. This new model of the Color Computer line was meant to better compete with the Apple II GS, Commodore Amiga and Atari ST systems.[dubious ] 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 ASIC called the "GIME" (Graphics Interrupt Memory Enhancement) chip. The GIME also provided additional features:

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)[1] 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).[2]

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.

Portions lifted from Wikipedia