Re: Can optimization-specific codes exist ?

Tom Lane (tgl@netcom.com) 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.


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

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