Here we go with Microcode again...

From: Huw Davies <>
Date: Wed May 20 02:23:55 1998

At 05:44 AM 19-05-98 -0700, Daniel A. Seagraves wrote:
>Digging thru the VAX 780 manuals...
>They have here some crud on how the microcode works. Where it starts and
>field definitions, etc.
>I know basically how microcode works. It's the one-cycle instructions like
>"gate data bus to address bus" or "gate data bus to ALU".
>One MOV can be 2-5 microinstructions.
>The large question I have is: How does the MOV translate to microcode?
>Does the VAX figure a microcode offset based on the opcode? Is there a table
>of entry points somewhere? How is this done?
>Another thing, the VAX 780 was microcoded from the console RX01. Does anyone
>have a copy of that RX01? Can anyone get a disk image? What else was on
>(RT-11? P/OS?)

Well, a large stretch away from my office chair reveals (hidden on the top
shelf under 10 years or so of dust) three manuals:

        VAX 11/780 Microprogramming Tools User's Guide AA-H306A-TE
        VAX 11/780 Data Path Description AA-H307A-TE
        Micro2 User's Guide Reference Manual AA-H531A-TE

These date from the days when some people around here had delusions of
grandeur regarding their ability to write microcode programs. A very quick
look shows that probably all the answers are in the VAX 11/780 Data Path
Description manual. If I didn't have a major planning project to do by
yesterday I might spend some time browsing. Hopefully there'll be someone
else on the list who has access to the manuals or actual practical experience.

>Just being annoying...

Never :-)

 Huw Davies | e-mail:
 Information Technology Services | Phone: +61 3 9479 1550 Fax: +61 3 9479
 La Trobe University | "If God had wanted soccer played in the
 Melbourne Australia 3083 | air, the sky would be painted green"
Received on Wed May 20 1998 - 02:23:55 BST

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