13 Jul
2024
13 Jul
'24
4:03 a.m.
It appears that Dave Horsfall <dave(a)horsfall.org> said:
On Sat, 12 Jul 2024, John R 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.
Bill replaced it with a few simpler instructions and the comment
; Comet sucks
R's,
John
PS: For you young folks, Comet was DEC's internal project name for the /750.
Our Vaxes ran Unix so it was all C other than a
few things like tracking
down a bug in the 11/750's microcode that broke an instruction in the
inner loop of printf(). [...]
Do tell...