13 Jul
2024
13 Jul
'24
6:27 a.m.
On Sat, 12 Jul 2024, John Levine wrote:
The details are a litle dim after 45 years, but there
was a MOVTUC
instruction in the inner loop of printf that scanned for the null at the
end of the string. The /750 had a microcode bug that didn't matter for
the way DEC's software used it but broke the libc and I think also the
kernel version. MOVTUC sets six registers and we probably used one they
didn't.
I am reminded of the time when overlapped seeks on the RK-11 were
implemented in Unix, per the Peripherals Handbook.
They didn't work.
DEC responded with "Well, you were running Unix!"...
We then ran "DECEX" (their own diagnostic tool), which indeed failed
on overlapped seekson the RK-11.
It turned out that DEC never used overlapped seeks in their own stuff...
-- Dave