22 May
2009
22 May
'09
8:39 a.m.
On 22 May 2009 at 1:59, bfranchuk at jetnet.ab.ca wrote:
Well this is new 18 bit computer I have heard of ... I
guess more on
topic than say a PC clone. > >
The A and B registers in a CDC 6000 series machine were 18 bits (CPU
word was 60 bits). Eventually, this created problems, when more than
128KW was available on a CPU (lots of code used signed addresses to
signify this and that. Conditional branches were performed on the
sign or contents of a register, not on a condition code, so it could
get a little tricky doing 18-bit unsigned comparisons).
There were, however, plenty of 36 bit mainframes from various
manufacturers.
--Chuck