28 May
2024
28 May
'24
10:27 p.m.
Mike Katz wrote:
I want to add to this argument and ask Is bit 0 the
high order bit
(like on the PDP-8) or the low order bit (like on the 6809)?
It's the same across all PDPs... except maybe the 11, I'm sure someone
will remind me.
There are good arguments for numbering "bit N" such that its value is
2^N. With PDP-style bit numbering, it's quite awkward if you have
several different word lengths so that bit 0 have different value
depending on what kind of word you're dealing with.
However, it's not entirely clear cut. In many situations data inside
words are arranged "left to right" and in this case the PDP numbering
sometimes is more convenient than the opposite.