On Wed, Aug 26, 2020 at 9:59 AM Noel Chiappa <jnc@mercury.lcs.mit.edu> wrote:
    > From: John Cowan

    > That's always true on the PDP-11 and Vax ... because the processor
    > architecture (which has pre-increment and post-decrement instructions,
    > but not their counterparts)

After Doug's message, I carefull re-read this, and I'm not sure it's correct?
The PDP-11 has pre-decrement and post-increment, not the other way around (as
above) - unless I'm misunderstanding what you meant by those terms?

That's why:

        *p++ = 0;

turns (if p is in R2) into

        CLR     (R2)+

R2 is used, and then incremented after it has been used.

This quirk of the PDP-11 is why I still prefer post-increment and pre-decrement in my code... even though there's no chance in hades that my code will ever run there...

Warner