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The IBM PCjr and Tandy 1000

Here's a quick roadmap into the various rooms of this Shrine:

  • History and Memories of the IBM PCjr and Tandy 1000
  • PCjr/Tandy Enhanced Sound
  • PCjr/Tandy Enhanced Graphics
  • Hidden PCjr/Tandy surprises
  • Assorted PCjr/Tandy trivia
  • Related links
  • Bibliography

  • History and Memories of the IBM PCjr and Tandy 1000

    The IBM PCjr

    [PCjr with chiclet keyboard]After conquering the business computer market in 1983, IBM decided that they could expand their business to the home market with a redesigned version of the IBM PC. Cheaper and more tailored to the needs of the entire home, they launched the IBM PCjr in 1984.

    To better compete with the other home PCs of the time like the Commodore 64 and Apple ][, they made several changes to the "stock" IBM PC. More appealing to home users since they were fast and durable, IBM put two cartridge ports on the PCjr. Games and educational titles could be loaded easily and quickly by children; they just push the cart in and turn it on. No commands to learn (or floppy disks to bend).

    An extremely significant design enhancement made to the PCjr was increased graphics and sound capabilities. In addition to CGA's normal 320x200x4 and 640x200x2 limited-color and monochrome graphics modes, the PCjr was also able to produce 160x100x16, 160x200x16, 320x200x16, and 640x200x4 color graphics modes--the 16-color modes used the same color palette as color text mode. The sound enhancement came from the addition of a Texas Instruments SN76496 chip, a three-voice tone generator. This increased the number of voices from one to three, with 16 volume levels for each channel, and noise-generation for sound effects. IBM was banking on these enhancements to propel the PCjr to the top of the heap, so to help it along they hired Sierra specifically to do a next-generation PCjr game that would use the extra colors and sound. This resulted in the genre-creating King's Quest, but also explains one of the reasons why early Sierra games only used a resolution of 160x200 even when higher resolutions were available: 160x200 in 16 colors was the PCjr resolution used for King's Quest, and they kept using the same graphics engine in their games for several years.

    In addition to the enhanced graphics and sound capabilities, IBM decided to create a new keyboard for the PCjr with two drastic design changes: It was wireless, and it used rubber "chiclet" keys. The use of chiclet keys was an interesting decision, apparently made mainly to ease home users into computing. "My copy of king's quest 1 had a template for the chicklet keyboard with all the commands on it. That was the whole idea behind the keyboard, so that software people can give you a template to put over your keyboard that shows what all the functions do." j And the wireless keyboard was very convienent; you could type while reclining in your favorite easy chair, and since there was a RCA jack for composite color output to TV, you could hook it up to the family TV for everyone's enjoyment. While the keyboard was wireless, it could be connected to the PCjr directly for when you had no batteries. "The keyboard cord was pretty cool; it was simply a flat telephone-like wire. It even had an RJ11-type phone plug for hooking it to the keyboard." j

    Unfortunately, the PCjr didn't do well. The launch of the PCjr was overshadowed by Apple's much more intriguing launch of the Macintosh at the same time. But, marketing aside, the PCjr was almost doomed to fail due to some serious design flaws that even the enhanced graphics and sound couldn't fix. The keyboard, what IBM thought would be considered a great innovation, was ultimately its largest drawback--while it claimed you could be 6 feet or more away from the computer in wireless mode, most people found they had to be no further than about two or three feet from the computer. This distance limitation itself was only part of the problem: "It was a 14-inch monitor, so how far away would you possibly want to sit away from it?"j The AA batteries that powered the keyboard in wireless mode would also drain fairly quickly. In an effort to make the keyboard fit onto your lap easier, the key layout was compressed into a smaller form factor, so the function keys shared space with the normal 1-0 keys. To enter a function key, you had to hold down an "Fn" key as you pressed a number key. The numeric keypad was also dropped. As if all this wasn't enough, the rubber "chiclet" keys proved almost unusable for touch typing, making word processing for experienced typists a chore.

    [PCjr with joystick, later keyboard and one expansion module]There were other drawbacks as well that put the final nails in the coffin: The PCjr's expandibility was not as well thought-out as the PC. Expansion was performed through the use of modules that attached to the side of the machine. You could continue to add modules, but this kept expanding the side of the machine. "Memory expansion on the PCjr was via these 2" thick side addition thingies. You simply remove the cover on the side of the main unit and screw one of these things onto it, then attach the cover onto the add-on unit and you can keep building it from there. (Kind of like lego building blocks.) If you wanted to upgrade from the stock 128k to 640k, you'd wind up with an additional 8 inches of computer! If I recall, the parallel port was also in one of these side card things. So if you wanted everything maxed out, it looked REALLY dorky. Eventually 3rd party companies came around for replacing the memory in a 128k addon card so that you could upgrade to 640k with only 1 add-on piece."j Finally, the cartridge ports never really caught on, since software from companies other than IBM was very slow in coming, and the cartridge versions were never really as powerful as the diskette versions due to the smaller storage capacity of carts.

    IBM attempted some disaster recovery a year later with the release of a new keyboard. Gone were the rubber chiclet keys, replaced by true keys (albeit still with a reduced-size layout). The power consumption and response of the keyboard's wireless operation was improved as well. But by this time, it was too late; other manufacturers had either eclipsed the PCjr's graphics or sound capabilities (Commodore 64, Amiga 500), or cost less (Commodore 64, Atari ST), or had a large established base of educational titles (Apple ][)--all of which appealed to home buyers.

    IBM eventually discontinued the PCjr less than two years after its release, a dismal failure.

    The Tandy 1000

    [Jim's Tandy 1000]Tandy saw the huge success of the IBM PC and wanted to get into the market so that its large base of TRS-80 users had something viable to upgrade to. At the time Tandy was evaluating the PC market, the PC AT didn't exist yet, only the PC XT and the PCjr--and the PCjr had better graphics and sound. So it was natural for Tandy to choose the PCjr as the machine to clone.

    The only problem was that the PCjr was selling very badly before the Tandy 1000 was released. Tandy quickly changed all the advertising and marketing to take the focus away from the PCjr. "All they needed to created the monster 'white elephant' of all time was to announce the 1000 as a PCjr compatible. :-) So that's why the catalogs showed the machine as an MS-DOS compatible - which it was, but none of their advertising called it 'PC compatible' - though many consumers relate 'MS-DOS compatible' to mean 'PC compatible.'" b

    The Tandy 1000 was indeed a strange beast: The graphics and sound were mostly compatible with the PCjr's enhanced graphics and sound, but the keyboard and joystick connections were neither PC nor PCjr compatible--they were large, round, circular DIN connectors that were pin-for-pin compatible with the TRS-80 line. The Tandy 1000 also included the RCA TV output jack of the PCjr, so that TRS-80 users who had used their TVs as monitors could continue to do so. Because of this and other design changes (such as the length of the case, which was about two inches too short to accept full-length expansion cards), Tandy was criticized for creating a seemingly proprietary machine. "It was not proprietary. It was completely software compatible with the machine it was meant to be a copy of, the IBM PCJr. The only problem was that the PCJr was not a successful product and was discontinued just weeks before the 1000 came out."f

    Despite this, the Tandy 1000 because successful whereas the PCjr had not. The keyboard, while still slightly awkward, was not the horrific "chiclet" keyboard that the PCjr had used. Tandy's Radio Shack line of stores also made purchasing the computer easy--you could walk into any Radio Shack with a fistfull of cash and walk out with a Tandy 1000, complete with software and accessories. For the TRS-80 customers who wanted to upgrade, the base unit was all they needed, since they could reuse their existing monitor/TV, joysticks, printers, etc.

    The best thing about the Tandy 1000 becoming successful was that it still retained the enhanced graphics and sound capabilities of the PCjr--and game companies noticed. Over 300 game titles were released in the 1980's that use the extra colors or sound to enhance the game. Because of these game titles, some of which directly drove the sales of the Tandy 1000, Tandy decided to keep the enhanced graphics and sound in future models. "It became its own standard. Many times over the next few years, design decisions were made to be PC AT compatible or be 1000 compatible within the 1000 line."f Because of this, gaming on the PC platform was changed forever. We take the inclusion of sound and music into today's games for granted, but it was innovative and ahead of its time in 1985.

    Once VGA and sound boards became mainstream, there was little reason to own a Tandy that specifically catered to the old standards. "The Tandy 1000 TL/3, 1000 RL/2 and 1000 RL-HD were the last. Most of these appeared in the 1992 catalog (printed Fall 1991). The 1000-RLX that appeared in the fall of 1992 was VGA-based, but still had the PSSJ sound hardware, as did the 1000-RSX."f


    The following is an excerpt from a 1984 interview with Roberta Williams that illustrates the big changes both IBM and Sierra had for the PCjr and the gaming industry:

    Q: Where will the progression go from there?

    A: My new game is a big change! It's going to be on the PCjr.

    Q: Why the PCjr?

    A: IBM came to me a long time ago and asked me to write an adventure-type game for the forthcoming PCjr. They said it couldn't be like any other adventure game that had been done and it had to be replayable. And my type of game, usually, when you solve it once, that's it. There's no reason to play it again.

    Q: That's true of most adventure games, isn't it?

    A: Yes, except the fantasy/role playing games. Ultima or Wizardry you can replay because you have a character generator and you can make different things happen. But that's not my style. In effect, IBM was asking me to go against my style. And I couldn't think of any way to make my kind of game replayable without having a character generator. I thought a long time about this. I'd always wanted to have an animated adventure game, but the game I foresaw really couldn't be done on a computer that existed up to that point in time. Then I found out what the PCjr was capable of. I was really happy when I found out that this computer could do things other computers could not do. I could finally have my animated adventure game.

    Q: What's so special about the PCjr?

    A: It has sixteen solid colors. It's hard to do animation with artifacted colors [using patterns to simulate different colors--Ed.], but with solid colors things are much easier. Also, it has more memory -- 128K -- and it takes a lot of memory to do animation. My game will be available on the PCjr only until other computers come up to the game's requirements.

    ...some of interview skipped for brevity...

    Q: And this is all done with graphics as beautiful as those from The Dark Crystal?

    A: Better. The graphics are great. Your character is full color and the game has sound going most of the time. You hear little birds singing and doors creaking open and other things like that.

    Nostalgia wears rose-colored glasses, though, so I find it necessary to point out a couple of things that changed since that interview: King's Quest did indeed first only come out for the PCjr, but when it became apparent that the PCjr wasn't going to be the blockbuster success IBM predicted, Sierra quickly ported it to the PC, where it sold like gangbusters. They were able to port it so quickly because of the great design of their gaming interpreter, which they used for many different games and sequels from 1984 to 1989. Their interpreter was eventually ported to other home computer systems as well, bringing King's Quest along with it. Also, King's Quest wasn't really replayable, but it was difficult to reach a perfect score for completing all the steps, so you usually played it again to get a perfect score. (This was a far cry from the true replayability of Wizardry or Ultima, however, which she mentioned in the interview.)

    PCjr/Tandy Enhanced Sound

    Tandy 3-voice sound was a decent improvement over the PC speaker; you could have three distinct sound channels and 16 volume levels per channel. It doesn't sound like much, but it turned the harsh internal speaker into a nice melodic or sound effects device. Here's some comparisons:

    Program PC Speaker PCjr/Tandy
    Music Construction Set [MP3] [MP3]
    Silpheed [MP3] [MP3]

    While it wasn't nearly as powerful as the C64 SID chip, it was obviously a drastic improvement over the normal internal speaker.

    PCjr/Tandy Enhanced Graphics

    The 16-color palette of the PCjr and Tandy's new graphics modes was nothing amazing; it was the same 16 colors as text mode. But it still made one hell of a difference! One look at these comparisons and you can begin to see the rationale behind IBM's thinking--the graphics equaled or exceeded the capabilities of every other home computer of that time:

    A Comparison of CGA and PCjr/Tandy 1000 Enhanced Graphics
    King's Quest (160x200 screenshots taken from the 1987 re-release)
    4-color CGA (blue, green, yellow, red; patterns) 16-color PCjr/Tandy 1000

    It's interesting to note that the CGA screens aren't bad at all, given the limited color palette Sierra had to work with. The PCjr/Tandy screens are obviously better, but some clever use of patterns resulted in some good color approximations on CGA--for example, the three flags at the top of the castle and the cloth crests on the side of the castle in King's Quest.

    After King's Quest, Sierra stopped trying to make the 4-color CGA graphics look as good as they did, and concentrated on making the high-resolution 16-color graphics modes even better using 16-color patterns (a trick they learned supporting CGA). EGA was out by this time, but required an expensive video card upgrade. PCjr/Tandy users weren't disappointed at all, and got to see the enhancements without upgrading since their graphics subsystem already supported 320x200x16:

    Other Sierra Games (320x200 screenshots)
    4-color CGA (cyan, red, white, black; patterns) 16-color PCjr/Tandy 1000

    In the second Leisure Suit Larry 2 screenshot above, you can see that CGA was at a disadvantage: The name of the barber shop is only visible in 16 colors.

    Finally, you can see the improvement that 16-color PCjr/Tandy graphics had over regular CGA graphics in other various games:

    Other Misc. Games (320x200 screenshots)
    4-color CGA (cyan, magenta, white, black) 16-color PCjr/Tandy 1000

    Hidden PCjr/Tandy Surprises

    After 1988 or so, game companies were very quick to support the enhanced graphics and sound and advertise that fact on their packaging. But from 1984-1987, enhanced support trickled into some game titles without notice; if you didn't have a PCjr/Tandy at the time, you would have completely missed it.

    Thanks to supercooled futuristic technology, I've been able to capture and reproduce these hidden bits and pass the fun onto you. Some people went through a lot of trouble to support this new (at the time) emerging hardware after a comfortable 4 years of CGA and the PC speaker, and it would be a shame if this effort was lost forever. There's quite a bit of enhanced support here and there; for example:

    Assorted PCjr/Tandy 1000 trivia

    The 16-color graphics modes were a programming nightmare. They were similar to CGA, as they were also interlaced, but this time in four passes instead of two. :-P Another nasty thing was IBM's way of saving money: whenever you go into an extended graphics mode, it borrows RAM from the top of the free DOS heap -- your available DOS memory actually decreases by as much as 32K. Just make sure you don't have anything in that area before you initialize graphics mode... ;-) This is why you see things like "Requires 256K for EGA, 384K for Tandy" on old game requirement descriptions, since the extra bit of DOS RAM needed to fuel graphics modes pushed the memory requirements over the edge.

    Thanks to the RCA composite video output jack that was built into the PCjr and Tandy 1000, you could get 16-color graphics on some titles that didn't specifically support PCjr/Tandy special graphics, but did support 16-color composite color mode (which "translates" the 640x200x2 mode into a 160x200x16 mode). Starflight used this, as did California Games, and some others. You got 16 real colors--using the same method as the Apple ][.

    The Tandy 1000 and 1000 HD are actually slightly *slower* than 4.77MHz -- my testing shows them at about 4.6 MHz. But that doesn't make them the slowest PCs ever released; that award goes to the IBM PCjr thanks to IBM removing a few components (like fully-working DMA) and running programs from display RAM in an effort to reduce cost.

    Related Links


    j Jeff Leyda (

    f Frank Durda IV (unable to find current email address)

    b Bill Vermillion ( |

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