RE: large NPOT rowbytes
RE: large NPOT rowbytes
- Subject: RE: large NPOT rowbytes
- From: Jeff Laing <email@hidden>
- Date: Fri, 3 Dec 2004 09:37:38 +1100
> > Who knows, long ago in a prehistoric age of computing,
> there might have
> > been machines with distinct address and data registers
Thats right, make me feel old.
> It's a long time ago now, but I used to program DEC-10 machines where
> pointers consisted of (I think, - the details are hazy now) a 18-bit
> word address plus a 6-bit byte size and a 6 bit bit-offset
I'll go you one better. I worked on Honeywell mainframes running GCOS -
trivia buffs go look up the name of the fields in the 'passwd' structure on
Unix.
This machine also had 36 bit registers, which could hold either 6 6-bit
EBCDIC characters, or 4 9-bit characters. Yes, on these machines, "byte" =
"9 bits".
Memory was accessed 36 bits at a time, accessing single characters was
unnatural.
The machine could only address 34-bits, and pointers were stored in the TOP
34 bits of the word. Thus, to address memory location 10, you used (10<<2).
ie, this was a machine where sizeof(int) > sizeof(void*), an assumption that
youngsters these days like to make.
> Ah, those were the days,
> when programmers were real programmers...
... and we had to pay computer center owner tuppence a month for permission
to come to work, and when we'd get home, our mum and dad would kill us and
dance on our graves singing Hallelujah.
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