segmented memory models
cclist at sydex.com
Sun Aug 3 12:51:22 CDT 2008
On 2 Aug 2008 at 21:48, Andy Holt wrote:
> Is it possible that when designing the 8086, it's architect already
> had in mind the 286? In that processor the segments are capable of
> implementing a Multics-style OS. [that would assume the 8086 was a
> "quick hack" to tide Intel over until the technology for better chips
It wouldn't surprise me that an 80286-like chip was on the drawing
board when the 8086 was launched. Intel tended to think pretty far
ahead back then. Indeed, the 432 had segments.
> And at that time the coming dominance of Unix-derived OS's (or of
> Microsoft) was not as obvious as we now may think with 20-20 hindsight.
Multics-derived OSes weren't the only game in town using protection
schemes back then. When the 8086 was launched, OS memory protection
was very much current thinking, just as OOP and message-passing OSes
were current mainstream thought when the 432 was designed.
An earlier comment was made about "home PCs" not being seen when the
first generation of 16-bit chips were deployed. That may have been
true, but "business computers" were very much part of mainstream
thought. Chip manufacturers could look at the success of the likes
of the DEC and DG minis and easily see where the future was pointed.
I do recall that the Intel rep did say that the 432 was designed as
an Ada machine. That may have been speculation on the part of
marketing type, but it demonstrates where the thinking was.
What's ironic to me is that the i960 RISC processor arose out of the
ashes of the very-very-CISC 432. From one extreme to the other.
Another curiosity was the interesting game thatSiemens was playing.
Around 1978 they paired up with AMD to form a joint venture called
"American Micro Computers" or AMC to develop a support base for the
Z8000. When that flopped, they tried the same approach with Intel a
few years later with a joint venture, called BiiN to develop a
support base for the i960, which ultimately flopped. I have some AMC
manuals, but no BiiN paper.
Does anyone own any of the development system hardware produced by
either AMC or BiiN? It should be pretty rare.
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