16 Aug
2025
16 Aug
'25
6:01 a.m.
Warner Losh writes:
I suspect that it was the absence of a signed right
shift. In my
Decsystem-20 OS class, one of the differences between the compiler on
the VAX and the compiler on the '20 was that -1 >> 1 was -1 on the VAX
and 2^35-1 on the '20.
The DEC-20 (aka PDP-10) does have a signed right shift instruction.
Apparently the compiler didn't use it.