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UnderColor, Volume 1, Number 4, February 1, 1985

  • Title: Reviews
  • Author: empty
  • Synopsis: empty
  • Page Scans: Link


Jarb Electronics


Mark Data Products

Super Pro








Since its introduction, the Color Computer has been supplied by Tandy with three different keyboards. For the first two or three years Tandy’s gray-cased units came with a "chicklets" keyboard. They then switched to cream-, and then white-cased units, and began supplying full-sized keys on the keyboard. These keys looked "squashed" however . . . they did not rise much above the level of the keyboard background. More recently Tandy has begun to ship Color 2’s with full-sized keyboards with textured and sculpted keys.

The first two keyboards (chicklets and the first improvement to full-sized keys) were quite useable for occasional programming but distinctly inferior for word processing. The keyboard currently supplied by Tandy is not that bad for typing, though the key travel on it is to my taste unpleasantly short. All three keyboards, however, appear to be rather similarly (cheaply) made. The first two clearly demonstrated a tendency to wear out quickly with heavy use. I suspect that the current model will also not prove very durable.

lf you own one of the older keyboards you’II certainly want to consider buying a third party replacement for it. Even it you own a new one you might want to replace it if you don’t like the short keystroke travel it offers. What options do you have?

Hardware Hacker Options: The extremely poor quality of the original "chicklets" keyboard provided a fertile area for third party support. For the hacker, Dennis Kitsz (in an article in January, 1982, '80 Micro) described how to modify an old Model I keyboard and install it in the Color Computer. He observed that as those keyboards were being pulled from service they could be had for $10 to $15 from cooperative Tandy computer repair people. Currently, the old Model lll keyboards are being pulled from Mid III’s that are being upgraded to Model 4 status. I’ve bought about half a dozen of these for $5 to $10 each. These are excellent keyboards and their existing wiring is nearly the same as that of the Color’s keyboard. Only a few trace cuts and jumpers need be added. To help you install these keyboards get a schematic for the Color keyboard and for the Mod I or III. You’ll find that only four keys of one row are in a different place. Just trace this row out on your board and make appropriate changes. I do not recommend wiring a non-Tandy keyboard up from scratch. I’ve done this myself, once, and it is an outrageous waste of time! If you want to "do it yourseIf" stay with a Mod I or lll keyboard.

If you’re going to be hacking let me make a suggestion—connect it with a 15—conductor cable! I have a Mod ll type keyboard mounted in an old Mod I shell connected via a piece of 20-conductor shielded ribbon cable. I’ve wired up a Reset button and a power-on light on the keyboard as well. As I type this article I’m reclining in my easy chair with the keyboard on my lap. I make one mistake in the design of my lap keyboard: forgot to make it with a "palm rest." That is, I neglected to find or build

a case for it that had a minimum of three inches of space below the space bar. I’m correcting this flaw in the second remote keyboard I’m building now. One other note: the early CoCo’s had a pin connector for the keyboard. The current ones have an edge card/ribbon connector. Male connectors to the new kind of keyboard are hard to come by. You may decide to desolder the keyboard connector and install your own connector. I like to use DB15 or DB25 type connectors as they are highly available and highly reliable.

Commercial Options: The first commercial replacement keyboard on the market was to my knowledge a $120 remote keyboard from Jarb in San Diego. This was a very nice unit, though I’m not sure if it's still available.

Mark Data then introduced the "Super Pro" keyboard. This is currently the least expensive, available for $65 plus shipping and handling from Mark Data Products. It has become one of the very most popular keyboards. The mechanism is identical to the old Model I (Hi Tec brand) keyboards. Later on HJL introduced its keyboard, which features membrane switches (very durable) and sells for around $85. Micronix entered the market first with its "professional" keyboard (a piece of trash with weirdly positioned keys and too strong springs) and then a new keyboard (a very nice ALPs type keyboard that is almost identical in touch and feel to that of the Model III). Finally, Keytronics has a keyboard on the market, too. Both the Keytronic product and the Micronix product sell for around $85.

Deciding which keyboard to use is a very subjective affair. Some keyboards that I like others hate, and vice versa. My bias is toward medium key travel and medium mushiness and a textured feel. I tend to like the Model lll keyboard very much, though it’s a little too mushy to be perfect.

If you like the old Model l keyboards you’ll like the Super Pro; a keyboard that is identical to the Model lll keyboard is the Micronix premium. It's a very fine unit. The HJL keyboard has, to my taste, the most pleasing textured feel. I’ve used one extensively and like it very much. It's quite crisp in its feel, with a reasonable length of key travel. I’m biased against the Keytronic’s unit; for my taste it has much too short a key travel distance. But if you like the keyboard on the current Tandy Color machines you’ll like the Keytronics. Both have very short key travel. The Keytronics resembles a number of IBM PC keyboard copies.

Because all of the above products are much more likely to withstand prolonged use (the HJL is probably the most durable of the lot) they are to be preferred to even the current Tandy keyboards. One final note: these keyboards offer two or four extra "function" keys. This relates to the fact that in its design of the CoCo, Tandy left out four possible switch positions on the matrix it used. Now if Tandy had, from the start, used those four positions, it might have been nice (I'd have liked a designated control

key). However, since they weren’t used, virtually no available software supports such added function keys. If you happen to buy a keyboard with those extra keys I recommend you ignore them entirely.

I broke off the four function keys on my HJL keyboard when I found myself hitting them accidentally instead of the shift keys. (end)


Radio Shack

Fort Worth, TX


COC0 Bus


POB 813

N. Bergen, NJ 07042

$150 assembled $23 bare board

Over the last two years a number of expansion system ports have been introduced for the Color Computer. Only two have seen relatively widespread use by myself, my friends, and the circle of hackers who congregate on the Color Computer Special Interest Group: Multipak and the PBJ "C-C Bus." There have been other products but those products have either been withdrawn from the market or are in very limited use due to their limited capabilities, high prices, or both.

The Tandy Multipak sells for $160 list although it has been discounted by Tandy to $79 and $99 on several occasions. The PBJ C-C Bus sells for $150 assembled and tested but is also available as a bare board with full documentation for $23. The Tandy product offers four extra system slots; the PBJ product offers six slots. The Tandy product offers control of slot selection via hardware (an extemal switch) and software (POKEs to a given port in the $FFXX region). The PBJ product selects its slots via software only. The Tandy product comes in a more or less attractive white plastic case with a built-in power supply. The PBJ product looks rather more stark and has an external power supply (a wall transformer type unit). The Tandy product provides mechanical support (via its case) for its vertically mounted plug·in cards. The PBJ product provides no mechanical support for the card you plug in to it . . . they just sit there, held in by the force of the 40—conductor edge connector socket. The Tandy product provides full and proper grounding from the ground tabs of the CoCo to ground clips supplied on the Multipak. The PBJ C-C bus provides no connection between the CoCo’s ground tabs and any ground tabs that might be on cards you plug in.

Regarding the lack of proper grounding on the PBJ product: observant and sophisticated PBJ C-C bus owners use the product, and none have reported any difficulties with the C-C bus that might relate to bad grounding. Specifically, I'd fear that disk I/O might be subject to infrequent failures. But no PBJ bus owners have reported this to me. Al of PBJ (a very conscientious fellow) also informs me that no one has ever complained to him about such problems. I still don’t like the lack of ground tabs on his product, but must make it clear that all current empirical evidence indicates that the "oversight" has not affected the reliability of the product at all. (Those who own PBJ C-C buses who want to add such ground clips should try making them out of bent fuse clip holders.)

There has been one complaint on the Sig that the power supply for the PBJ C-C bus is a bit too weak to handle five cards plugged in simultaneously, though it seems that one of those five cards was unusually power hungry in the first place. From what I’ve heard, I suspect that the Tandy Multipak would not have had enough juice either.

Going to a more technical level, there are two or three other comparisons between these two items that are important. The Tandy Multipak offers (under software control) switching among its four slots of both the CTS ("ROM select line") and the SCS (port select line) independently. The C-C Bus offers only combined switching of the CTS and SCS line together. With some sophisticated hardware cards (such as video digitizers and EPROM programmer cards) this may result in the PBJ C-C bus having problems. In most cases, this deficiency will not be noticed. The Tandy Multipak has a tinned male connector to the CoCo.

Both buses have gold-plated edge·card female connectors for the plug-in boards. The NMI and HALT lines are not buffered on the Tandy Multipak. This oversight results in the SAM and CPU being at high risk of being destroyed if you accidentally plug in or remove a card in the Multipak while the power is on. The PBJ C-C bus does buffer the NMI line, resulting in an added degree of protection to the CoCo itself. The Tandy Multipak uses a PAL (program array logic) chip to do a lot of its address decoding. Unfortunately, the programming of that PAL chip is not published by Tandy in its service manual for that product. The PAL is not hard to read . . . Tandy did not blow the verification links. Most folks, however, do not have PAL readers handy. The upshot of all this is that there were some addressing idiosyncrasies that were not apparent from the Multipak's documentation that caused serious problems for some hardware designers. The PAL refuses to allow writing to memory in the address space between $8000—$FEFF even if you've decoded your own chip select line directly from the address bus.

The PBJ C-C Bus uses small scale logic only to do its address decoding, and so holds no nasty surprises for hardware designers using it. The designer of the PBJ board (Alberto of PBJ) is available for consultation with his customers.

ln both the Multipak and the PBJ C-C bus, assembled and tested versions, the chips are all soldered (with the exception of the PAL chip in the Tandy product). But you can order the C-C bus as

a bare board and so have the option of socketing its chips.

Recommendations: The two units have different strong points and different weaknesses. In many cases the weaknesses of either may be corrected by a minimum of hardware tinkering. To the hardware switching among the cards plugged into the number of slots and more straightforward address decoding would make it much more attractive, as does its availability as a bare board with instructions. To the casual purchaser, I might recommend

the Tandy Multipak. Being Tandy, it's going to be something of a standard. And if you buy it on sale it is more attractively priced than the assembled and tested C-C bus unit. Although PBJ is extremely swift in supporting repairs for many folks, it's just much more convenient to take a blown item back to a Radio Shack dealer. Finally, the availability of external hardware switching among the cards plugged in to the Tandy Multipak will make it more attractive for those who want to use it to switch among ROM packs. (end)

TRS-80 Models I, III, & Color Computer Interfacing Projects by William Barden, Jr.

Howard W. Sams & Co., Inc.

4300 West 62nd St.

Indianapolis, Indiana 46268

$14.95 paperback

One of the opening sentences in this book says it best: "the Color Computer has an amazing amount of circuitry built into it for the price." That has been the secret of the Color Computer's success: a versatile, yet inexpensive, machine that has something for everyone.

TRS-80 Models I, III, & Color Computer Interfacing Projects by William Barden, Jr. is directed towards the person who would like to learn about hardware and interfacing aspects and explore the way software and hardware work together to make a computer and its peripherals communicate with each other. Much of the book exploits the interfaces already present in Radio Shack computers. The joystick inputs are actually low-resolution analog-to-digital converters so the single most vital function needed for data acquisition is already built-in.

Likewise, the serial ports that provide the printer and cassette recorder are fine for single-bit input/output. Mr. Barden provides a virtual feast of projects using these built-in interfaces, for everything from temperature and light-intensity measurements to voice storage and playback; from telephone dialing to wind-speed measurement. The entire book was essentially published as a year-long series in BYTE (December, 1981-November, 1982): readers with access to those back issues can enjoy this material and save the price of the book. The latter chapters cover more general interfacing through the expansion connectors. Barden constructs general-purpose I/O boards for the expansion ports of the three computers, and gives simple applications, such as switch-closure detection, relay driving, and analog/digital or digital/analog converter interfacing. The book concludes with a useful discussion of signal conditioning and transducers for sensing outside-world signals.

Mr. Barden is well-known for his readable and practical tutorials, and this book is no disappointment. Every effort has been made to accommodate the novice, but Barden manages to do it in a way that shouldn't bore even a moderately advanced reader. His projects include complete parts lists and wiring-point tables to help people who are uncomfortable with schematic diagrams. The book covers such a variety of different applications that it's hard to imagine anyone not finding something interest

here. There's a good balance of coverage and projects for each of the three computers. Color Computer enthusiasts need not beware the inclusion of other machines in this book: there’s plenty here for I users of any of the machines to get their money's worth.

I, had only a couple of minor complaints, both directed at Chapters 16 and 17, which deal with use of the Color Computer expansion connector and a general-purpose I/O board for it. This material was prepared before Radio Shack’s introduction of the latest revision of the full-size circuit board (the so-called F board), and before the introduction of the

Color Computer 2. Barden uses the CTS signal,

which_is the $C000 select at pin 32 of the expansion connector, to address his I/O device. That's fine for Revision E circuit boards and earlier, but the F board, the CoCo 2, and earlier boards that have been retrofitted for 64K RAM all use gates that disable the CTS line for write operations. Only read operations will generate the $C000 select on those machines:

thus, his CoCo interface project won’t work, and his descriptions of how to write to an I/O device plugged into the cartridge port are obsolete for machines produced since October,1982 or so. The $FF40 select at pin 36 should be substituted for CTS, as it's active for both input and output on all machines:

Also, Barden uses the 8255 chip, an old I/O device introduced originally as a member of the 8080 microprocessor family. This device does have 24 I/O lines rather than the 16 of newer chips, but the lines are less configurable and the programming for the 8255 is unnecessarily complicated by today’s standards. The 8255 is OK for the Models I and III, which use 8080/Z-80 technology, but I would much rather see a 6820 or 6522 for the CoCo expansion. Those chips are designed for the 6800/6809/6502 family of microprocessors, and are more representative of modern hardware.

This is an excellent book for nearly everyone who is interested in learning about interfacing and simple hardware construction. With the warning in mind about using the I/O board with newer CoCos, the projects are useful and should serve well to introduce owners of these computers to the fascinating world of data acquisition and control. (end)


Pilgrim's Progress




Christmas Quiz




3-Game Pack




Church Time




Quality Christian Software

Dept. A, P.O. Box 1899

Duncan, OK 73534

’Way back in 1979, when I was sending out a free newsletter for TRS-80 owners, I would often receive original programs in return. One of these was "Bible Verse Hangman" by Stan Ockers, a midwestern KIM-1 specialist, and the other, by up-and-coming programmer Joe Teller, was "Shipwreck." The Bible Verse game was a hit around the house, since not only did you have to guess the Bible verse as you filled in the blanks, but you could guess chapter and verse as well. Nobody ever got "hanged," just gently admonished. "Shipwreck" was a satisfying but fairly typical adventure game of the sea-and-sand variety. Neighborhood youngsters loved it; there was none of the typical adventure violence, just survival dependent on wits and skill.

Half a decade later, four of us (one "test" minister, two Christians, and an atheist) gathered ’round the old monitor to have a crack at some new programs from Quality Christian Software: "Pilgrim’s Progress," "Church Time," "Christmas Quiz," and the "3-Game Pack." Our mutual feelings about these programs is reflected by one reaction: how good can a commercial program on a religious topic be when its authors hyphenate and spell incorrectly, and misspell the names of books and characters in the Bible?

That's not a minor dissatisfaction; in fact, it disturbed our test minister enough that, although he might have considered using some of the programs as reinforcement pastimes for his religious classes, he scrapped the idea due to the host of minor inaccuracies. Furthermore, in the 3-Game Pack (the best of the quiz-game lot), one question had two correct answers, but only one answer was accepted. In another game, choosing the correct response depended on which translation of the Bible is used.

All the QCS programs loaded on the first try, although Pilgrim’s Progress required a pre-run PMODE0:PCLEAR1 when used with early computers. During our experience, none of the programs crashed with an error message.

It’s difficult not to take an un-Christian attitude toward these Christian programs. Originality and better programming should be expected, but I want to forgive those limitations in the belief that the programmers have placed evangelical mission above details. Somehow I feel sure that all my complaints are devils dancing on the head of a pin. In fact, QCS President Terry Presgrove forbids program copying, although "one exception . . . would be the sharing of QCS software with non-Christian owners for evangelistic purposes." Hard to fault that generosity, I suppose.

"Church Time" and "Pilgrim's Progress" are both adventure games. "Church Time" operates under the quirky premise that you've left for church, forgotten your Bible, gone back to get it, and locked yourself in the house. You have to get out of the house and to church on time (reminds me of a song. . .). "Pilgrim’s Progress" is more complex and serious, based on John Bunyan’s theological treatise of Christian growth. The objects of the game,

according to the documentation, "is to obtain all Nine Fruits of the Spirit. Your progress is directed away from the city of Destruction and toward the Holy City. Important doctrines are grasped as the player proceeds."

The best adventure game was "Pilgrim's Progress," since it was the most serious, the most thoroughly constructed and had the largest repertoire of responses. John Bunyan's original "Pilgrim’s Progress" is not on the best-seller list these days. It would have helped to have a summary of the book, since so much of the game's plan was based on it; in fact, the documentation as a whole was poor for the QCS games. Documentation for "Pilgrim's Progress" is the longest, and is—excluding the message from the QCS president—just over one side of a page.

None of us—not our test minister, our Christians, or our atheist—did well. Perhaps America is a latter day Sodom and Gomorrah, but we always ended up (rather, ended down) in the fiery kingdom. The statement "important doctrines are grasped as the player proceeds" turned out false for us.

Unless you are a hard-core adventure maniac ready to play anything that comes along, or a Christian hungry for any software at all, "Pilgrim’s Progress" and especially "Church Time" are only mediocre implementations of the adventure game principle.

The quiz games were more immediate and satisfying. Many of the Bible verses, especially those from the Old Testament, were tricky, and the "Christmas Quiz" questions centered around popular myths that are often unsupported by Biblical reference. No, the actual number of wise men is never stated, only inferred from the three gifts that they bring. All the drills are timed, and the "Who Did That" and "Who Said That" games are decidedly slippery. One of our test Christians had a better handle on Bible references than the minister, yet she often stumbled on questions about Old Testament women, characters of similar name (Elijah and Elisha), and obscure books (Nahum and Titus). After a round or two, though, the initial enjoyment wore thin as the available references ran out and the grammar and spelling problems grew more irritating.

Quality Christian Software claims that these programs teach Christian principles. If I’m to believe the programs themselves, though, "Christian principles" essentially mean aphorisms. There are no monsters to kill in the adventures ("Thou shalt not kill," of course), and clues to getting around are given if you enter PRAY. Temperance is encouraged; if you stop for a donut in "Church Time," you lose—they’re jelly donuts, the jelly gets on your clothes, and you’re late for church.

These programs from America’s Bible Belt don’t always carry the same message to those of us Down East. Perhaps we’re too hasty or more demanding or less godly. But I mentioned "Bible Verse Hangman" and "Shipwreck" because they hold at least as much interest as the offerings of QCS-and they were written in 1979. Even if you believe OCS is dealing in a limited audience and a specialty topic, more interesting and more thoroughly researched programs should be expected in 1984. (end)