13 Dec
2022
13 Dec
'22
3:53 a.m.
On Tue, 13 Dec 2022, Rudi Blom wrote:
I vaguely remember having read here about 'clever
code' which took into
account the time a magnetic drum needed to rotate in order to optimise
access.
Sounds like you're referring to SOAP (Symbolic Optimal Assembly Program)
on the IBM 650; the programmer wrote the code "straight down" and SOAP
reordered it for rotational latency.
Similarly I can imagine that with resource restraints
you sometimes need to
be clever in order to get your program to fit. Of course, any such
cleverness needs extra documentation.
Try writing a bootstrap program in 512 bytes :-) Self-modifying code was
the order of the day...
I only ever programmed in user space but even then
without lots of comment
in my code I may already start wondering what I did after only a few months
past.
You could be clever in kernel space too, such as taking advantage of
the DATIP/DATO cycles on DEC's Unibus when updating a memory word i.e.
read/modify/write.
-- Dave