Oldskooler Ramblings

the unlikely child born of the home computer wars

25 Years of Junior

Posted by Trixter on November 6, 2008

25 years ago, IBM announced the IBM PCjr.  23 years ago, they killed it as swiftly as one would kill an attacking weasel.  IBM had good reason to bury it:  It misinterpreted its audience, didn’t forecast for the future properly, was too expensive, and most ironically, it wasn’t as IBM PC-compatible as some clones.  But just before it died, it managed to infect the industry with a few innovations that continue to this day.

Let me hit you up with some PCjr 101.  Your time is valuable, so I’m going to ditch the long boring history lesson and get right to the juicy stuff. Here are main features that set the PCjr apart from the PC — along with the good, the bad, and the ugly:

Feature The Good The Bad The Ugly
Used “sidecars” instead of slots Very easy to expand the machine without opening it Locked you into IBM proprietary expansions You could quite literally double the width of the machine with a crapload of sidecars attached to it
No DMA capability Kept the cost down for consumers CPU was required to transfer data from floppy disk The entire machine ground to a complete halt every time the floppy disk was accessed, which made downloading from BBSes an exercise in frustration
Memory-mapped video Use as many video pages as you need; no more CGA “snow” All of main memory was now display memory, which needed slow wait states to be compatible with the video hardware Because of the wait states, the PCjr was the only PC ever created that was slower than the original IBM PC
Initially limited to 128KB Kept the cost down for consumers Because of memory-mapped video, any decent PCjr graphics mode with two video pages meant there was no memory left for programs 128KB machine was only fully usable via BASIC, since BASIC was in ROM and didn’t take up system RAM. Memory expansion sidecars were required to approach rudimentary compatibility with most PC programs.
16-color graphics All 16 text colors could be used up to 320×200, and 4 colors in 640×200 More colors = more memory to sling around = slower screen updates More colors = less main memory for apps, so most third-party games required an additional 128KB to use PCjr modes
3-voice sound 3 individual tones plus noise channel Noise channel inflexible unless you were willing to give up one of the frequency channels; clock divider meant frequencies couldn’t go lower than 110Hz Thanks to the idiotic clock divider locking you out of lower octaves, most audio on the PCjr was one octave higher than usual making everything sound like a kid’s music box
PCjr-specific monitor Was cheaper than other RGB monitors and had a speaker built-in; matched dimensions and style of system unit Image quality was substantially fuzzier than most RGB monitors; had proprietary connector that could only be used by the PCjr PC Speaker sound could not be routed to the external monitor speaker, which means the monitor’s speaker was useless unless 3-voice sound was playing
Keyboard used rubber keys Spaces between the keys meant that custom application overlays could cover the entire keyboard Keys had zero tactile feedback (although you could enable an audio keyclick) Touch-typing on the rubber “chiclet” keyboard was impossible unless you were willing to live with nerve damage.  A few months after the PCjr launch, IBM provided a free replacement keyboard with more typical keys.
Keyboard was wireless Could sit on the living room couch and use PCjr Infra-red technology limited use to line-of-sight at six feet or less A lot of people ended up buying the keyboard cord
Cartridge slots Cartridges boot instantly; larger programs like Lotus 1-2-3 could be put into cart ROM, making them usable with only 128KB RAM Carts were limited to 64K; hardly any software came out in cartridge form The space the cartridge slots took up could have been used better as space for a second disk drive, something IBM never offered for the PCjr.  Quirk: PCjr forcibly rebooted when a cartridge was inserted or removed.

The Bad outweighed The Good just enough for consumers to buy other machines, so IBM discontinued the PCjr 18 months after it had launched it. Even the release of several third-party addons that tried to bolt on necessary functionality (memory beyond 128KB, 2nd disk drives, hard drive, faster processor, etc.) could not save it.  Poor PCjr never had a chance to make an impression…

…or did it?  Tandy, in the creation of their Tandy 1000, had chosen the PCjr as the machine to clone+enhance.  When the Tandy 1000 was released in 1985, it had all of the good stuff of the PC (DMA, ISA slots, hard drive capability, memory up to 640K) as well as the PCjr (16-color graphics, 3-voice sound).  Even better: Sierra, through their prior agreement with IBM, already had games both published and in development with full support for PCjr Tandy graphics and sound.  The Tandy was cheap, you could buy it at any Radio Shack, and — most importantly — get face-to-face support for it at any Radio Shack, which appealed to first-time home computer buyers.  It was a runaway success, and little PCjr’s graphics and sound legacy got dragged along for the ride, forever changing how the PC was perceived as a gaming platform.

There is a small corner of my heart reserved for the PCjr (and the Tandy 1000 as well), but by far the sweetest love letter you will find for the PCjr is Mike Brutman’s PCjr Page.  Head on over.

28 Responses to “25 Years of Junior”

  1. Grr. No “I know the machine but have never seen one” option in the poll. Grr again.

  2. Me said

    Agree (^)

  3. Trixter said


  4. Me said

    It shoud actually have been more like “I have heard of it, but never owned nor used one”

  5. Trixter said


    (be kind, this is my first poll :-)

  6. Chris said

    The closest I got was a mint Tandy 1000SX that I had to dispose of a few years ago :( . I did know the owner/CEO of PC Enterprises though (a company that provided a ton of 3rd party PCjr hardware). He lived in the condo directly above my grandmother’s and built my first PC back in 1993. (486 DX/2 66Mhz just in case you were wondering)

  7. […] of the PCjr. IBM’s PCjr was killed only 18th months after being revealed and [Trixter] lays out exactly why. Overall, it was designed to be cheap to produce and sell, but many of the choices made it […]

  8. […] of the PCjr. IBM’s PCjr was killed only 18th months after being revealed and [Trixter] lays out exactly why. Overall, it was designed to be cheap to produce and sell, but many of the choices made it […]

  9. Roy said

    I never owned one, but I used one at a job and ended up writing software for it. Floating point was out. The Borland Turbo C library was too big to fit in memory with the rest of the application.

  10. The Steven said

    Between the PCjr. and the Tandy2000… take the Tandy2000

    2 720K 5-1/4 floppies
    up to 765K of RAM
    8Mhz 80186 processor
    3 internal “euro” slots
    optional 10Mb HD
    EGA-ish video

  11. Chris said

    Somewhat related and cool. Scans of old Radio Shack catalogs. See how much those Tandy 1000 setups cost back in the day.


  12. anon said

    I had a Tandy 1000 TX in 1988. 8MHz 80286 with upgraded memory (768k) and a 20MB hard disk card. It was my first computer and it was certainly high-end for the time. It even had a 3 1/2″ floppy drive when 5 1/4″ reigned supreme.

    I was always puzzled why Mac fans always derided the PC as having inferior sound and graphics. I didn’t find out until almost 1990 that most IBM clones didn’t have the nice graphics and sound capabilities of the Tandy.

    Someone gave me a free mint-condition PCjr in 1998 or so. It didn’t have any software and I didn’t know where to get any, so I ended up selling it to a collector for something like $50. I remember the keyboard used an infrared connection, but it didn’t have rubber keys, it was basically a normal-looking keyboard.

  13. Servo said

    I still have a PCjr! Unfortunately the monitor died, but the system itself is still working fine. I really wish IBM had included the PCjr’s sound in all their following computers…When done right PCjr/Tandy sound could be rather impressive! There’s even a few games I think sound better than their C64 counterpart…

    The Tandy 2000 was a really bad choice if you wanted to play games though; its compability wasn’t very good. Nothing supported its enhanced graphics, so if you got a game to work at all on that system you got CGA (it wasn’t fully CGA compatible so some stuff didn’t work). Was also missing the enhanced sound.

  14. […] of the PCjr. IBM’s PCjr was killed only 18th months after being revealed and [Trixter] lays out exactly why. Overall, it was designed to be cheap to produce and sell, but many of the choices made it […]

  15. I’m the Mike referenced by Trixter.

    One important aspect of the PCjr that gets missed often is that the lack of capability on the machine led to a very healthy market for 3rd parties. They ran the gamut from small dealers with hackish hard drive solutions to very elegant (and pricey) SCSI subsystems capable of driving hard drives and CDROMs. Keyboards, mice, second floppy drive systems, etc. were provided by large and small companies alike.

    It also forced an owner who wanted to upgrade a PCjr to get intimate with the machine. If you wanted a second floppy drive on the machine you often got out the soldering iron and modified the floppy controller yourself. Wanted a memory upgrade? Desolder the 64Kb chips in the add-on sidecar, replace with sockets and 256Kb chips, cut a trace, and hope you didn’t create any solder connections.

    Even on the software side hacks were plentiful. This was the first IBM machine that was BIOS compatible but not fully hardware compatible with the 5150. There were a lot of hacks to get communications programs to recognize the serial ports correctly, hacks to get the video display correct on games, and you *always* needed a device driver to recognize more than 128KB.

    For too many people this challenge was too much to bear, and the machine earned it’s poor reputation. But for the rest of us, the limitations forced us to learn the machine and how to exploit it. And that made quite a few PCjr owners the superstar programmers and IT professionals that they are today.

    Now we just need a demo worthy of the machine .. come on Trixter!


  16. Todd Henkel said

    I still think the biggest downfall for the PCjr was the keyboard and the name. I worked at Radio Shack at the time. People buying computers then (if not now) wanted the best and latest of everything. Buying a “junior” of anything? Forget it. The neighbor has something new and I need something bigger and faster. The kiddie keyboard? Ha! I want the latest and fastest processor with the most memory even though I might only be typing a letter. Keeping up with the Jones’s was the main driver I saw day in and day out.

    But the Tandy 1000 series was the best IMHO. Best graphics, best sound and best value. And at least in my store we knew enough to help most people out.

    “The Steven” – The Tandy 2000 sucked. You may have the layout of Bill Gates loving the old T2000. But the compatibility issue

  17. Hackineer said

    I have a PCjr. It’s set up on its own desk in the corner of the room I’m in right now. It still worked the last time I turned it on, which was probably a couple years ago.

  18. danno said

    I hated that machine. My parents bought one as our first computer. IBM stole my father’s money. The IR had to be lined up exactly for the keyboard to use. Just bump the cartridge and you loose everything. So frustrating to use that system. I lost a doc after a marathon writing session. I know save often. Still, I hated that machine.

  19. Brandon H said

    I had a PCjr, ran it for somewhere between 4 and 6 years I think?

    Original keyboard – sucked. Ate batteries like nobody’s business, not to mention the key travel was crap.

    On-board 64KB of RAM – sucked. It was 120ns or slower RAM, made the whole system run slower than it should’ve. If you had more RAM and configured jrConfig correctly, you got WAY better speed. MIPS and other benchmarks proved it.

    You could get up to 768KB of RAM on the unit (736KB usable) – 64K on-board + the 64KB card that eventually came standard with the unit, + 512-640KB of sidecar expansions. I think late in the game there might’ve been larger memory sidecars available too.

    When all was said and done, I had a parallel port sidecar, 128KB memory expansion sidecar, 512KB memory expansion sidecar, 720K 3.5-inch drive add-on on top, thin font ROM, NEC V20 running at 9.54 MHz, PC/PCjr switch on the front (replaced the IR receiver), wired full 83-key keyboard with click action from NMI (not 100% sure on the company name), joystick, jrAccelerator cartridge (pseudo-NMI, caps/scroll/num lock indicators), cartridge BASIC, a Mouse Systems optical mouse, a 1200 baud Kyocera modem, Tandy 1000 graphics mod (made it more compatible with Tandy graphics software – there *were* a few differences), and still the original PCjr Color Display with speaker.

    Broke the NEC V20 accelerator board and had to get a friend to solder new pins in… had to replace the floppy drive once… that’s how I broke the accelerator board – stupid tray the floppy mounted in was near-impossible to remove!

    Using the wonderful jrConfig.sys device driver I maxed out at 736KB of usable memory in DOS. IIRC, I ran IBM DOS 2.1 at first, then upgraded to IBM DOS 3.3

    Good times. I even wrote a little app in Turbo Pascal with inline assembly (I didn’t have an assembler at the time) that toggled one of the sound bits. That combined with one of the MILES sound drivers made Tandy 1000 games that previously didn’t have sound on the jr work with sound. TMNT was one that comes to mind… I named the app jrSound or jrSnd I think, but I can’t find the source or executable anymore. Lost to the bit bucket in the sky…

    Lots of good memories there.

    Went straight from PCjr to a 486DX/33. Man, was that a change!!

  20. rand said

    Used one in my first job to write chromatography visualization software. I remember using edlin to write because nothing else loaded fast enough and that it often seized up if you typed during heavy floppy access like an assembly run. When the Mac came out I jumped and never looked back – far superior.

  21. Chris Robison said

    Back in 1985 my parents bought a Tandy 1000a (as identified only by the small sticker on the back; I understand that the true, original “Tandy 1000” was very short-lived, and IBM sued Tandy over it due to some IP infringement in the BIOS or something). I was the only person in the family that used it (I was in elementary school at the time) and it, along with the Apple II computers at my school, became the foundation of my software programming career.

    I remember the hours of frustration wondering why the programs I wrote didn’t work, as I slowly learned that the Tandy 1000 wasn’t really quite “IBM PC compatible” but different in many ways, especially regarding video and sound. Over time i figured out how the video and sound chips were actually better, and learned how to work with them in Basic and later Pascal. Ultimately ended up getting a 286 upgrade and a memory expansion to 640k, but the machine never did see a hard disk. Those were the days.

  22. Greg said

    I got a PCjr for Christmas when I was a kid. I remember being extremely confused because all my friends had an Apple. I didn’t know what a PC was. The store sold us DOS Extension, not DOS so we couldn’t even use the thing (except BASIC) at first. I think I ended up with 4 sidecars: 2 memory upgrades, a parallel port, and a power supply sidecar to power the other 3 sidecars.

    My fondest memory was when the disk drive started to go bad. I would have to open the case and slide the R/W head back and forth a few times. The drive would have a small seizure then start reading the disk.

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  24. Charlie said

    I had a jr, moreover, I still have it.

    I used the computer for a long time, long into the 286 era. I learnt a lot, both hardware and software.

    It was the time when you were able to understand everything inside the machine; hardware was descrete, on chip for each function.

    Together with my brother were able to even make an audio input by sampling pwm on the joystick’s button.

    We ended up having 2 1.2Mb floppys, the hack for 640kb memory, IBM’s RGB monitor, IBM’s ProPrinter (before that one, the IBM Graphics printer), joystick, mouse, Basic Cartridge, a home made hard reset button on the other cartdrige bay (very usefull :) ), modem.. I can’t remember anything else.

    Ah, software! Flight Simulator, Home Budget, and some sort of word processor I can’t recall the name, all on their original boxes. At the end, two boxes full of floppies.

    Really very good memories, loved it.


  25. polpo said

    I never owned a PCJr, but I sure used them a lot. The computer lab at my elementary school was filled with ’em. They were mainly used for Bank Street Writer (word processing), LogoWriter (a weird combo of word processing, Logo, and HyperCard), Where In The World is Carmen Sandiego, and Oregon Trail (of course). I have to say that the PCJr jump started my interest in computers.

  26. had one many years ago it was great for the times, never will forget it, my sister got it for me.

  27. Galane said

    The video and audio weren’t quite the same as the way Tandy used them. There were simple hardware hacks to make the PCjr simultaneously compatible with its own modes and Tandy modes.

    I only did the video hack on mine, never could find the audio hack info online. IBM’s Canadian website used to have the Tandy video hack and the second floppy hack.

    I had one of the “2nd story” style expansions with parallel port in an extra tall sidecar which connected the memory expansion board in the upper section where the second floppy drive was. This system didn’t require any hacking of the floppy controller.

    The other upgrade I had was an NEC V20 CPU, not on an accelerator board. Running 22-NICE to access the Z-80 it ran CP/M faster than a 12Mhz 286 emulating a Z-80 and faster than my Xerox 820-II Information Processor.

    IBM also had a speech synthesizer using the same TI chip as in TI’s own synth for their 99-4/A but IBM’s implementation was nowhere near as good so very little software used it.

    It’s too bad IBM didn’t start with the PCjx, a grey version that was pretty much the same (IIRC the rear ports may be different) but with dual floppy drives. Sold only in Japan.

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