Nice CPUs (was: Virtual vs Physical memory (was Re: Designing around a 6502 )) - test-drb@ccmp.vtda.org

12 Feb 2003

...
 From: "Hans Franke"
&lt;Hans.Franke(a)mch20.sbs.de&gt;

  >> > A segmented architecture...
 >> I have one word to say about segmented architecture... "Ewwwww"

  >:) I like segmented systems. It's one of
the best concepts for
 >address space extension. Ok, I also think that the 8086 is one
 >of the best 16 Bit CPUs (*1) ever, and as the 186 core at the 
   Then you'll love the Z8000. Its segments are
non-overlapping
 ( unless a mmu makes them so ). 
I never had a problem with overlaping. Programming is always
a matter of diszipline, and well written code never accesses
unassigned data :)

The Z8000 was always a bit weired. a nice design, but weired.
Ok, I never programmed it, only thinking around when I had to
choose a processor for a system around 1980. The candidates
where 16016, 68000, Z8000, 8086 and 9900.
The 8086 droped out because of the complicated bus structure,
the 9900 because 64K where not enough, otherwise it would have
been my choice (and the 99000 wasn't realy available). So the
finalists where National vs. Motorola vs. Zilog. After all,
the NS16000 did offer the best extensibility, a complete and
beliveable family model and a real nice and clean programming
model. So 16016 it was.

   I like the 186 myself but have to admit that the
time for
 segmented memory has passed, in general purpose computing. 
Well, define general purpose computing. In my eyes this
describes real computers ... ala IBMish Mainframes, and
Segmented memory never had a place there. When going for
small systems, the 186 is still one of the best CPUs to
use. Powerfull, fast, simple and high integrated. I don't
know anything which can't be done in a megabyte of mem. 
Hi Hans
 We agree here. The only hard part of working with the
186's is getting the init sequence debugged. Once that
is done they are great.
 I don't think that I've ever written
a program that took more than about 35K ( not counting data
space ). Then again, most of the larger programs I've written
were in Forth so it is hard to compare.
Dwight

...

Gruss
H.

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