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By Glen VanDenBiggelaar

Last updated November 23, 2005

The CoCo was a very popular seller, so about 1984 Tandy decided to give the CoCo a sleek new design, drop the familiar "silver" case and give the computer "beige" feel. They upgraded the processor and bumped up the Ram. They also dropped the "TRS-80" from the logo and just used "Tandy". The Tandy label appears to coincide accurately with yet another variation among CoCo 2 models: the presence of the enhanced MC6847T1 VDG (Video Display Generator) chip therein. Every original CoCo and the majority of CoCo 2s (those displaying the TRS-80 label) use the earlier MC6847. As its name implies, the VDG generates the CoCo's video output. The plain 6847 version contains only uppercase characters in its internal character set, whereas the 6847T1 also contains lowercase characters. Note that software and hardware solutions have been created to overcome this limitation of the 6847, without which lowercase characters are displayed as reverse-video uppercase characters. Conversely, while the 6847T1 is capable of generating true hardware-based lowercase, that capability is seldom exploited. Apparently, the clock generator could be programmed to generate a double-speed clock of 1.8 MHz.
It should be also noted that even though the "melted" keyboard looks identical to the CoCo 1's -26-3003b (white model), the CoCo 2's keyboard was vastly inferior, and cheaply made (compaired to the CoCo1's). The "melted" keyboard is not as responsive than the "enhanced" .

First Released: 1983 CPU: 8 bit 6809E  Clock speed: 0.89 MHz Bus type: Tandy Proprietary Data bus width:  8 - bit Address bus width: 16 - bit Memory        Standard on system board 16K Maximum on system board 32k (early models) or 64K Maximum total memory 64K ROM: 8 kbytes, containing the standard version of Microsoft BASIC. An optional upgrade to the
full version of the Microsoft Colour BASIC existed, pushing the ROM size to 16 kbytes Ports: Bus connector/Cartridge connector for game cartridges. Two analog joystick connectors. Tape player/recorder connector, 1500 baud interface. RS-232 serial port. TV connector (RF modulator) Video: 9 colors were available: the standard eight video colors plus orange. The displayed colors had to be selected from two predefined four-color palettes for four-colour modes, and two predefined two-colour palettes for two-color modes.	The 26-0327 (16k Extended Basic) with the Melted Keyboard. E-bay photo.
No color switching was possible. Special variations of display modes were possible, by exploiting the 6847's flexibility Audio: The CoCo II uses a 6-bit DAC (Digital-to-Analog Converter), controlled by the CPU. This allows for 64 different volume levels, and quite a bit of fancy sounds (speech and other samples, for instance). But, since the DAC was under CPU control, sounds taxed performance quite a lot. Storage : Tape and Floppy Operating System: Note that most CoCo 2s use version 1.2 of the Color BASIC ROM, and all Extended CoCo 2s use version 1.1 of Extended BASIC (the two ROM versions are independent). Ebay Photo	Even the boxes were relabeled! , There is a more rare third variant of the CoCo2 Box with blue, this is the only picture I could find. I have never seen one on Ebay
Close up of the "Enhanced Keyboard"	Close up of the "Melted Keyboard"

The orginal CoCo 2's ( 26-3026/27 and 3127's) had the Channel select switch above the "to TV" jack because the RF Modulator was mounted verticaly


Back outputs of all later CoCo2 Models

The following is information of model numbers for the CoCo 2. This information was pulled off various web sites, and I cannot confirm its authenticity,

26-3026
This is the first model of CoCo 2. Built in the USA, it came equipped with 16 kilobytes of RAM, Color BASIC only, and the 'melted' keyboard. Most of its chips are socketed. This machine is based on the #8709416 PC board, and has a large, upright RF modulator with integrated TV channel 3/4 switch. Also characteristic of this machine is the use of a large power supply pass transistor (in a TO-3 package). The two 24-pin ROM sockets are located near the cartridge/system bus connector, and the eight RAM chips are located in a single row under the keyboard.
(Note that this same model number has reportedly been found on larger, Korean-made CoCo models in Australia.)

26-3027
This machine is identical to the 26-3026, with the exception that it already has the Extended BASIC ROM factory-installed. To upgrade the 26-3026 or 26-3027 to 64 KB of RAM, it is necessary to replace the eight 8040517 chips with 4164 chips of 200 ns or better access time, and to solder a wire between the two pads labeled W1. W1 is located between U6 and U7.
Click Here for step by step instructions on how to upgrade the 3026 and 3027 to 64K.

26-3127
This is the first '64K Color Computer 2'. It contains the Extended BASIC ROM, and either the melted or the 'enhanced' keyboard (I have both, the "enhanced version is a Canadian model), and 64 kilobytes of RAM (naturally). Otherwise, it is identical to the 26-3026/26-3027. Note that the RAM is soldered in place in those machines which were factory-equipped with 64K, making replacement thereof a bit more difficult if necessary. For this reason, the 26-3026 and 26-3027 variants are favorites of most people.

26-3134
This is the first Korean-made 16K Color BASIC CoCo 2. It uses the #20261043 circuit board, which differs considerably from that used in the earlier USA-made models. Virtually every component on the board has been relocated. The RF modulator is now a smaller unit, lying flat on the board rather than standing upright, and the channel 3/4 switch has been moved to the main board from the modulator. The positions of the various switches and connectors on the PC board (and therefore on the rear panel) differ from those of the previous machines as well. The RAM chips are located in two rows (one of five and one of three chips). This machine has a metal 'cage' surrounding the power transformer, which was not present in previous models. The power supply utilizes a cooler-running pass transistor (in a TO-220 package). The RF modulator, power transformer, pass transistor, and switch/jack location characteristics of this machine persist on all subsequent models. Most chips are soldered in place on this and all subsequent boards as well.

26-3136
This machine is identical to the 26-3134, but with the Extended BASIC ROM factory-installed.
To upgrade the 26-3134 or 26-3136 to 64 KB of RAM, it is necessary to replace the eight 8040517 chips with 4164 chips of 200 ns or better access time, and to solder a wire between the two pads labeled J1. J1 is located next to IC7.

26-3134A
This is the next Korean 16K Color BASIC CoCo 2. It utilizes a #20261044 circuit board, which differs considerably from the previous versions. This board's RAM is in the form of two socketed 4416 chips. The preferred 64K upgrade for this board involves replacing them with two 4464 chips. However, the option exists (by means of several special connectors on the board) of a factory upgrade consisting of eight 4164 chips on a daughterboard. Legend has it that the option of using either 4164s or 4464s was incorporated for economic reasons (the pricing and availability of RAM were quite unstable when these machines were manufactured). Additionally, this board introduces the use of a single 28-pin ROM socket. A 24-pin ROM containing only Color BASIC 1.3 shipped in that socket in this model. With appropriate jumpering, this socket is able to accept a 27128 EPROM.

26-3136A
This machine is the 16K Extended BASIC version of the 26-3134A. It uses a single 28-pin, 16-kilobyte ROM containing both Color BASIC and Extended BASIC.

26-3134B
This is the last Korean 16K Color BASIC model. It uses the #20261058 circuit board, which is similar to the #20261044 board. It uses two 4416 RAM chips and a 24-pin Color BASIC 1.3 ROM in a 28-pin socket as well. However, in addition to the 4416/4464 sockets and special daughterboard connectors, there are pads on the board allowing direct factory installation of eight 4164 chips. This is also the board which contains the newer 6847T1 VDG chip (which is not pin-compatible with the earlier 6847).

26-3136B
This machine is the Extended BASIC version of the 26-3134B.
To upgrade a 26-3134A, 26-3136A, 26-3134B, or 26-3136B to 64 KB of RAM, it is necessary to replace the two 4416 chips with 4464 chips of 200 ns or better access time, and to solder a jumper across the two pads labeled RAM SIZE 64K. The RAM SIZE 64K jumper is located next to IC4.

26-3127B
The last model number associated with the 64K Extended BASIC CoCo 2, this is an odd one indeed. The author has no less than three distinctly different machines, each bearing this exact model number. One is a USA-made TRS-80 with a #20261044 board and a 6847, one is a USA-made Tandy with a #20261058 board and a 6847T1, and one is a Korean-made Tandy with a #20261058 board and a 6847T1. Contrary to some rumors, the presence of the 'B' in the model number does NOT necessarily indicate the presence of a 6847T1. As noted previously, the Tandy label appears to be the best external indication thereof. One absolutely accurate method of determining if one is present is to type a '0' (zero) on an operating machine. If the resulting character on the screen is displayed with a slash through it, the machine in question has a 6847T1.
On some Canadian (Korean Made) models, a wire mesh is underneath the went slots across the top of the unit. It is assumed that this is for added RF insulation, but the actual reason remains unknown.

NOTE: Information is still being compiled and confirmed about the various models, particularly those in the A- and B-series. Updates will likely be forthcoming......

The first Color Computer 2's Came with a big Blue Operations Manual. It was basically a reprint of the original Color Computer's Operation Manual only this time it was just printed with a new cover and in black and white, the original had green color on the pages. It also came with the "Quick Start Card"
They also came with the the familiar "Basic Manuals" although Tandy did add the number 2 to the covers, and again dropped the green color inside
When Tandy Decided to drop the TRS-80 Logo and just call them "Tandy" , The Operation Manual was dropped for the new "Introducing your Color Computer 2" Book. This was a smaller size and easer to handle. By this time, all the Color Computers shipping had Extended Basic included, Tandy merged both basic manuals into one book called "Getting Started with Extended Color Basic"
Tandy re-issued 3 known varianst of the Quick Start guide. One with a green Striped Cover, one with the familiar "Rainbow" Cover, and a red striped. It is not known if there is significant difference between the 3.
There is also a "third" rarer variant of the "Getting Started with Color Basic Manuals. It looks like they were a small version of the first ones, and I have seen both Tandy and Radio Shack on the covers. I tend to forget that not all CoCo 2's came with Extended Color Basic. This manuals came with those "BASIC" (pardon the pun) models. An Fun Fact that these books is that the also refer to the CoCo 2 as "The Deluxe Color Computer". (See below). These books had pink color in them instead of the green color that the other manuals had.

THE DELUXE COLOR COMPUTER
APRIL 2005
I have been e-mailed some information about the "Tandy Deluxe Color Computer". This information was supplied by L. Curtis Boyle (you can see his web site at : nitros9.stg.net.)

" The Deluxe Coco was being developed at one point in 1985, and was to
have 128K RAM, a RAM disk, the 57 key keyboard (that the Coco 3 eventually
got), and enhanced BASIC. It was in the prototype stage (Microware
actually had some in house for OS-9 development), but then they decided
that that small of an upgrade would have no chance competing with the
Atari ST, Amiga, etc. machines coming out at the time... so they dropped
it and went with the Coco 3 design instead. Some of this information came
from the original Microware employees who did the Coco 3 ROM's, and some
was from Mark Siegal of Tandy."

-Again I wish to thank Curtis for the update. It looks like when the above manual was written, Tandy planed to use it for that version also.

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