resurrecting the Intel iAPX-432 32-bit microprocessor

Eric Smith spacewar at
Wed Jul 22 13:33:44 CDT 2015

On Wed, Jul 22, 2015 at 8:32 AM, emanuel stiebler <emu at> wrote:
> Was a wonderful idea, but the performance of the 432 wasn't nearly what was
> promised.

I'm updating my dictionary to quote that as an example under the
definition of "understatement".

See "Performance Effects of Architectural Complexity in the Intel 432"
by Robert P. Colwell.

TL;DR: the inherent slowdowns imposed by the 432 architecture are
relatively small compared to the slowdowns imposed by hardware
implementation choices. Some of the hardware implementation choices
were forced by the limited die size that was practical to fabricate in
the late 1970s, but others were apparently made on the basis of
inadequate or flawed analysis.

Release 3.0 of the 432 architecture made several significant
improvements to performance within the limits of what could be done
without a complete hardware redesign, including using a preallocated
chain of context objects for the activation frames of a process rather
than allocating a new context object on each function call.
Unfortunately it was too little too late.

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