Re: Can optimization-specific codes exist ? (A Johnstone)
6 Oct 1999 09:17:10 -0400

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Re: Can optimization-specific codes exist ? (1999-10-06)
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From: (A Johnstone)
Newsgroups: comp.compilers
Date: 6 Oct 1999 09:17:10 -0400
Organization: Royal Holloway, University of London
References: 99-09-118 99-10-011 99-10-016 99-10-033
Keywords: architecture, comment

Tom Lane ( wrote:
: Au contraire: the old HYDRA/C.mmp project at CMU made good use of
: user-provided microcode in PDP 11/40E processors.

No, as I said, most PDP-11's were microcoded (not sure about the T-11
chip) but only the 11/60 was marketed with a WCS. There was no user
provided WCS for the 11/40.

"The PDP-11's used on C.mmp were slightly modified to provide software
protection and make the Pc's compatible with a multiprogramming
environment. Also, a writeable microstore was added to the 11/40's."

From: `The C.mmp/Hydra project: an architectural overview' Henry H
Mashburn in `Computer Structures: Principles and Examples' by Daniel P
Siewiorek, C Gordon Bell and Allen Newell

See also, `Computer Engineering: a DEC view of hardware systems
design' by C Gordon Bell, J Craig Mudge and John E McNamara

i.e. John's implication is right, you had to be friends with Gordon
Bell to write your own instructions for an 11/40.

Dr Adrian Johnstone, Senior Lecturer in Computing, Computer Science Dep,
Royal Holloway, University of London, Egham, Surrey, TW20 0EX, England.
Email Tel:+44(0)1784 443425 Fax:+44(0)1784 439786
[This has drifted too far away from compilers. -John]

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