30 Nov
2021
30 Nov
'21
9:18 a.m.
On Sun, Nov 28, 2021 at 05:12:44PM -0800, Larry McVoy wrote:
I remember Ken Witte (my TA for the PDP-11 class)
trying to get me to see
how easy it was to read the octal. If I remember correctly (and I probably
don't, this was ~40 years ago), the instructions were divided into fields,
so instruction, operand, operand and it was all regular, so you could see
that this was some form of an add or whatever, it got the values from
these registers and put it in that register.
I've looked it up and it is pretty much as Ken described. The weird thing
is that there is no need to do it like the PDP-11 did it, you could use
random numbers for each instruction and lots of processors did pretty
much that. The PDP-11 didn't, it was very uniform to the point that
Ken's ability to read octal made perfect sense. I was never that good
but a little google and reading and I can see how he got there.
Charles Sauer contacted me off list and sent me this:
https://notes.technologists.com/notes/2008/01/10/a-brief-history-of-dell-un…
Turns out that Ken was a big deal there. Not surprised at all.
--lm