The Apple IIGS Megahertz Myth
Dan Vincent (via Hacker News):
The Apple II and Commodore 64 with their 6502 and 6510 CPUs clocked at 1 MHz could trade blows with Z80 powered computers running at three times the clock speed. And the IIGS had the 6502’s 16-bit descendant: the 65C816. Steve Wozniak thought Western Design Center had something special with that chip. In a famous interview in the January 1985 issue of Byte magazine, Woz said,
“[the 65816] should be available soon in an 8 MHz version that will beat the pants off the 68000 in most applications, and in graphics applications it comes pretty close.” End quote. That’s already high praise, but he continues further: “An 8 MHz 65816 is about equivalent to a 16 MHz 68000 in speed, and a 16 MHz 68000 doesn’t exist.”
[…]
But that “should” in “should be available” was doing a lot of work. Eighteen months later when the IIGS finally shipped, there was no 8 MHz ‘816. It was as nonexistent as Woz’s imaginary 16MHz 68000. 8MHz chips were barely available three years later. What happened?
[…]
So why were IIGSes with chips rated at 4 MHz not running them at that speed? Why 2.8 MHz? Isn’t that… weirdly specific? Did an 8 MHz machine really get put on ice due to executive meddling? To solve these mysteries I descended into the depths of Usenet, usergroup newsletters, magazines, and interviews. My journey took me through a world of development Hell, problematic yields, and CPU cycle quirks.
Way back in ’85, a 4MHz ’816 cost noticably more than an 8MHz 68000. Things are going to be even more skewed now.
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Thanks for a great article.
For years (right up until I read your article), I had been telling people that Apple should've focused on the IIGS and not the Mac. I believed that faster '816 chips and later '832 chips were on the way, and would be able to keep the system competitive. And GS/OS was close enough to Mac OS that it really only needed a higher resolution screen. I thought that had Apple gone on that route, we'd probably have ended up in the same place today (PowerPC, Intel and Apple Silicon), with a very similar operating system, but without having trashed the entire ecosystem of Apple II computers, peripherals, software and users. Meaning better market penetration and without that huge loss of goodwill.
But now, having read that story about the nightmare of trying to produce '816 chips in quantity with reasonable clock speeds, I now realize I was flat-out wrong. Those faster '816 and '832 chips were never going to ship at all, let alone in mass-market quantities. Apple would've tied the company to a sinking ship, and would have been dragged down along with it.
Which just makes me a bit sad, because the IIGS was a great design, but chip availability just made impossible to realize the full vision behind that design.
Lately I have been remeniscing about my old Apple II with a Microsoft Soft Card Z80 coprocessor and a Videx 80 column video card. I recall I had to solder a wire to the back of the shift key and connect it to a pin in the joystick socket. Oh it was wonderful using CP/M and Wordstar on the Apple II, but the 80col card was the most useful for writing code in UCSD Pascal.
