How does microcode work??

From: Huw Davies <>
Date: Wed Jan 21 23:10:43 1998

At 12:52 AM 1/9/98 +0000, Tony Duell wrote:

>There have been many books written on microcoding and related subjects,
>and to try to sumarise them here would be rather difficult. The books
>that I seem to like on this include 'Microprogrammed System Design'
>(Florentin), 'Bit-Slice Mircoprocessor Design'(Mick & Brick), and the
>technical manuals for some of the PDP11's (the PDP11/45 one is what
>taught me microcoding) and the PERQs. There are plenty of others. The AMD
>2900 series databook is worth reading if you can find it.

I used to teach a course that used Microprogramming Primer by Harry Katzan,
Jr published by McGraw-Hill. My copy is now somewhat dog-eared and the
pages are yellow.... It's a nice mid-70s view of computer architecture :-)

>It's not necessarily ROM. Some machines had so-called writeable control
>stores (WCS) which allow the user to rewrite the system microcode.

It was a nice (but expensive) option on the VAX-11/780 series. The manuals
for that are sitting in my office somewhere - yep, up there near the
Bliss-32 manuals!

 Huw Davies | e-mail:
 Information Technology Services | Phone: +61 3 9479 1550 Fax: +61 3 9479
 La Trobe University | "My Alfas keep me poor in a monetary
 Melbourne Australia 3083 | sense, but rich in so many other ways"
Received on Wed Jan 21 1998 - 23:10:43 GMT

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