22 Aug
2015
22 Aug
'15
10:42 p.m.
On 08/22/2015 04:23 PM, Sean Conner wrote:
For my own morbid curiosity, and because it came up
on another mailing
list I'm on [1], what machines commercially avaialble were sign magnitude
and one's complement? Every machine I've encountered was two's complement
(okay, IEEE 754 [2] is a sign magnitude format but I'm talking about integer
implementations here, not floating point). I've only found reference to one
sign magnitude computer (the IBM 7090, release in 1959) and a few one's
complement machines (mostly the PDP series from DEC).
The LINC (Laboratory INstrument Computer) was one's
complement, with a 12-bit word. Several derivative machines
were the same. The most confusing, of course, were the
LINC-8 and PDP-12, which had the PDP-8 instruction set with
two's complement, and the LINC instruction set, with one's
complement, all in the SAME machine. SHEESH!
Jon