[This is a reply to a comment on Hackaday: https://hackaday.io/project/190838-ibm-pc-8088-replaced-with-a-motorola-68000]
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For some reason, I can't reply directly to your comment with the eejournal opinion piece [https://www.eejournal.com/article/how-the-intel-8088-got-its-bus/], but I suspect my earlier comment was too brief.
Let me try that again:
The 68000 had built-in support for 8-bit peripheral devices, both in the bus signals and the instruction set. Most of the popular implementations, including the Mac, made heavy use of 8-bit parts, and Motorola had application notes on interfacing other company's 8-bit devices as well as their own. You could mix 8-bit peripherals and 16-bit memory without stretching.
Motorola even had an app-note about interfacing the 68000 directly to 8-bit memory, but any decent engineer would have looked at the note and realized that the cost of 16-bit memory was not really enough to justify hobbling the 68000 to 8-bit memory. That's one of the reasons the 68008 didn't come out until a couple of years later, and the primary reason that very few people used it. There was no good engineering reason for it.
Well, there was one meaningful cost of 16-bit wide memory: You couldn't really build your introductory entry-level model with 4 kB of RAM using just eight 4 kilobit dRAMs. (cough. MC-10.) You were forced to the next level up, 8 kB.
IBM knew that the cost of RAM was coming down, and that they would be delivering relatively few with the base 16 kB RAM (16 kilobit by 8 wide) configuration. Starting at 32 kB (16 kilobit by 16) would not have killed the product. Similarly, the cost of the 68000 would come down, and they knew that.
Management was scared of that.
Something
you don't find easily on the Internet about the history of the IBM
Instruments S9000 was when the project started. My recollection was that it started before the 5150. It was definitely not later. It had much
more ambitious goals, and a much higher projected price tag, much more
in line with IBM's minicomputer series. There was a reason for the time
it took to develop and the price they sold it at. But even many of the
sales force in the computer industry didn't understand the cost of
software and other intangible development costs.
Consider how
much damage the 5150 did to IBM's existing desktop and minicomputer
lines. Word Processing? Word Perfect was one of the early killer apps
for the 8088-based PC. Spreadsheet? Etc.
IBM management knew too well that if they sold the 5150 with a 68000 in it instead of the 8088, a lot of their minicomputer customers were going to be complaining to high heavens about the price difference. They knew the answer, but their experience showed them that the too many of the customers would not believe it.
That was the real reason. They hoped the 8088
would be limited enough to give them time to maintain control of the
market disruption.
I think they were wrong. But it would have taken a level of foresight and vision that very few of management withing IBM had.(very few outside IBM, either.), to take the bull by the horns and drive the disruption.
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Anyway, my point was that higher cost wasn't the real reason any more than the (at the time, much-rumored) technical deficiencies of the 68000.
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