TTL computing

From: Thilo Schmidt <>
Date: Thu Apr 11 16:10:17 2002

On 10-Apr-2002 Richard Erlacher wrote:
> Well, my recollection may be different from that of others simply because of
> when it was formed, but back in the '70's, when bit-slice was becoming quite
> popular as a means for creating a computer from hardware of various sorts,
> the notion of microcode was used to describe the code for the particular
> bit-slice
> family, often the AMD 2900 series, that was used to create a specific design.
> Each instruction in the set attributed to the final target system was
> implemented in some number of more simple instructions for the bit-slice
> engine.
Looks like we where talking about only similar things with the same name.
I don't know the AMD2900 series, my definition of microcode was formed
back in 1999 in a lecture about gate-level-design...

And it isn't too exotic either (according to Roger Ivie's mail it was
used in the Design of the Firefox QBUS Adapter)

But I'm quite sure the purpose of the microcode was very similar.

What I think I found out (please correct me if I'm wrong):
The AMD2900 series provided small building-blocks for CPU
design (such as ALUs and stuff).
The "bit-slice-engine" you mentioned was the "Control Unit" of
the so assembled processor. This "Control Unit" was programmed
in a language you refer to as "microcode".
Microcode-machines like those Roger and I posted to this list
are almost exclusively used as "Control Units".
You think of a specific Microcode-Machine with a well
defined Microcode-Language and probably very sophisticated
If that's true we talked about basically the same thing.
(just in different languages) ;-)


Received on Thu Apr 11 2002 - 16:10:17 BST

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