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SubjectRe: Linux-asm (was A patch for linux 2.1.127)
On Thu, 19 Nov 1998, Simon Kenyon wrote:
[quote snipped]
> unix never ran on an 8
> it was originally developed (in assembler) on a 7
> when the moved from the 7 to the 11/45 they rewrote it in c

The reason you see the word "segment" here and there in Unix is probably
because the 11/45 had a two-segment memory mapping model. Having
separate "I-space and D-space" (instructions, data) doubled the
theoretical memory capacity of the machine, and by that time more memory
was a welcome improvement. This model also appeared on the earlier PDP10
systems (called HISEG/LOSEG there -- the HISEG was code and the LOSEG data).
Other PDP11 models had addin boards for segmented memory, but I think the
11/70 was the first that had (or could get) what we'd recognize as virtual

> now - what i don't know is how the c compiler was bootstrapped
> i have vague recollections that the first c compiler was written in bcpl (which was
> an interpreter written in assembler)

C has a long chain of ancestors. C <- B <- BCPL (basic CPL) <- CPL
(Combined Programming Language, I think) which doubtless came from
something else, but my knowledge stops there.

This thread should probably move to comp.os.old-fogeys or whatever.

Mark H. Wood, Lead System Programmer mwood@IUPUI.Edu
Innovation is only valuable if it improves one's life; otherwise it's
just one more silly change to cope with.

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