Oldskooler Ramblings

the unlikely child born of the home computer wars

Archive for November 6th, 2008

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.


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