[TUHS] In Memoriam: Per Brinch Hansen

[Doug McIlroy]

A tangential connection to early Unix experience:

My collection of early computer manuals includes Brinch Hansen's manual
for the RC 4000, which stands out for its precise description of the
CPU logic--in Algol 60! It's the only manual I have seen that offers a
good-to-the-last-bit formal description of the hardware.

DEC presented something of the sort for the PDP-11, but punted where
the woods got thick. When I wanted to know how they computed the last
bit of floating-point results, I got no satisfaction. Amidst a thorough
description of addressing came this formulation of the actual computation:
"form floating point result".

Doug