[vcf-midatlantic] Revised, My take on "what is vintage computing"

Herb Johnson hjohnson at retrotechnology.info
Wed Dec 23 18:51:28 EST 2020

>> "Bit slicing is a technique for constructing a processor from modules of
>> processors of smaller bit width, for the purpose of increasing the word length."

> Okay bit processors were CPU construction sets. :-)

In the late 70's, bit-slice processor sets were used for high-speed 
activities like floppy-drive and hard-drive controllers, maybe graphic 
boards, maybe fast-math boards. Microprocessors of the time were too 
slow. Chip-sets like Western Digital's for floppy or harddrive control 
(ie custom microcontrollers) weren't invented yet. Only mainframes and 
minis were a market for discrete-logic controllers. So bit slices filled 
a need at the time.

Look for old bit-slice stuff among those controllers, on S-100 and 
Multibus boards, and on mini's like PDP-8's, 11's, Novas, etc. You'll 
also see non-CMOS high-speed processors, like Signetics 8X300.

A kind of predecessor was ALU chips like the 74XX181 chips, with related 
carry and shift and register chips in the series. Again - minicomputer 
CPUs were often constructed from such chips. Some CPUs were made from 
bit slices too. They were all the bleeding edge at some point. David 
Gesswein mentioned the Tektronix graphic terminals as an example.

Regards, Herb   Johnson

Herbert R. Johnson, New Jersey in the USA
http://www.retrotechnology.com OR .net
preserve, recover, restore 1970's computing
email: hjohnson AT retrotechnology DOT com
or try later herbjohnson AT comcast DOT net

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