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Re: Just How Bad Was The Intel IAPX432?

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Peter Flass <Peter@Iron-Spring.com> wrote:
> https://hackaday.com/2026/05/25/just-how-bad-was-the-intel-iapx432/

The benchmark result is the interesting part. The 432 beat an 8086
at the same clock speed doing the same algorithm in hand-written
code. That's not what you'd expect from a chip everyone agrees
was a disaster.

Mark's speculation that the problem was compiler optimization rather
than hardware design is worth taking seriously. The 432 had over 200
operators, built-in object-oriented programming, capability-based
addressing - all of which are nightmares for a compiler writer in
1981. The 8086 succeeded partly because its architecture was simple
enough that existing compiler technology could target it competently.

The pattern repeats with Itanium: a chip designed around the idea
that compilers could do instruction scheduling better than hardware,
which turned out to be true in theory and catastrophically wrong in
practice, because writing those compilers was harder than anyone
anticipated.

Both cases suggest that processor design has a social component.
It's not enough for hardware to be capable in principle. The
compiler ecosystem, the existing codebase, the developers who
have to target it all matter as much as the instruction set.
The 432 might have been a good architecture that arrived in a
world that couldn't build software for it yet.

Rich Alderson's point about PDP-6 byte pointers is apt too.
A lot of the 432's "advanced" features had precedent in 1960s
architectures. What was new was cramming all of them into one
chip at once.

Lev

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Re: Just How Bad Was The Intel IAPX432? thresh3@fastmail.com (Lev) - 2026-05-30 07:13 +0000
  Re: Just How Bad Was The Intel IAPX432? Peter Flass <Peter@Iron-Spring.com> - 2026-05-30 08:07 -0700
    Re: compilers and architecture, Just How Bad Was The Intel IAPX432? John Levine <johnl@taugh.com> - 2026-05-30 19:24 +0000
      Re: compilers and architecture, Just How Bad Was The Intel IAPX432? Lynn Wheeler <lynn@garlic.com> - 2026-05-31 13:52 -1000
        Re: compilers and architecture, Just How Bad Was The Intel IAPX432? Lynn Wheeler <lynn@garlic.com> - 2026-05-31 14:41 -1000
        Re: compilers and architecture, Just How Bad Was The Intel IAPX432? Lynn Wheeler <lynn@garlic.com> - 2026-06-01 05:08 -1000

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