🚀 go-pugleaf

On Fri, 24 May 91 23:29:16 GMT <news%ucf1vm.BITNET%LILAC.BERKELEY.EDU@OHSTVMA.AC
>Wrong newsgroup.  IBM mainframes are not PC's (we wish).

Phil:

Why would you wish that IBM mainframes were the brain-dead architecture
that the PC uses?  You need the '386 before you can truly multitask safely,
and even if a 386 *can* go at 15MIPS, it's still useless because it
spends 12 of them doing loads and stores out of the 4 registers...

At the risk of starting a holy war, MS-DOS and the Intel 8x86 architecture
are the single worst thing to happen to computing.

Obligatory assembler question:

On small machines and handhelds (6502, HP-11, stuff like that), there's
a subculture involved in exploring undocumented opcodes, "synthetic
programming", and the like.

Does anybody out there have a war story of a "undocumented" opcode or
similar feature on an IBM 360/370/etc mainframe?  My personal favorite
was when I was doing MUSIC hacking, and a kernel routine of mine took a
branch to East Fishkill on an IBM 4341, hit a data area, and tried to
execute a SIGP instruction.  Oddly enough, it died on a privop
exception, not the regular operation exception you'd expect.  I never
got brave enough to explore whether the 4341 *really* had a SIGP
instruction, or whether CP's instruction simulation was doing something
to me....

And is it true that a 360/44 had its SS format instructions
intentionally removed to cripple it and keep it slower than the 360/50,
because the 44's floating point made it so much faster?

/Valdis