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From: LINDSAY@TL-20B.ARPA
Newsgroups: net.aviation
Subject: Re: obscure old memory technologies
Message-ID: <8603091952.AA08936@ucbvax.berkeley.edu>
Date: Sun, 9-Mar-86 13:40:24 EST
Article-I.D.: ucbvax.8603091952.AA08936
Posted: Sun Mar  9 13:40:24 1986
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People who would like to read further might try Husson's excellent book
on microprogramming, which I read in 1970 or thereabouts. He discussed
real live implementations, including one where you could whip up microcode
on a standard 80-column keypunch machine.

Then there was the Interdata Model 4, which I thought to be the best
minicomputer on the market ( in 1968, before the PDP-11 ). They offered
custom microcode: you provide the bit pattern, and they would weave it,
by having wires that did (or did not) pass through little U-shaped things.
I believe it worked on a principle of transformer coupling. IBM probably
had a similar technology, in which case it will be covered in Husson.

Don Lindsay
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