segmented memory models

[Chuck Guzis]

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
> existed] 

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.

Cheers,
Chuck