Re: [COFF] Building OS from source in the olden days

On Wed, 11 Nov 2020, Greg 'groggy' Lehey wrote: Depends what you mean by "olden days" and "big computer". As I recall we (Uni of NSW) had the source to the 360/50 and the Cyber 72, but not for the VMS stuff; binaries were patched with IEBUPDTE and later on SUPERZAP (possibly written locally). I got an official pat on the back for getting SPITBOL to work after its time-bombs (yes, plural) expired[*]... And we had the source to something called Unix Edition 5 & 6 etc, but they were hardly mainframes :-) [*] The first bomb failed with an error message, so I patched that. It then started crashing rather mysteriously, and I discovered that it was taking an indirect jump to whatever was in R0 at the time (I think). Rather than waste time digging them all out, I wrote a program that LOADed the binary, scanned memory for a word that matched that date, and printed each address so they could then be inspected by hand. There were something like six of them... One big SUPERZAP later, and we had a working SPITBOL compiler again; a bored CompSci student is terrible to behold. -- Dave