Quote:
Originally Posted by Keith956
Many years ago when I worked for Fairchild Semi, one of the chips I worked on was the F558 which was a 8 bit parallel multiplier. Well to cut a long story short another company (name escapes me) had an LS part out, so we bought one, took the lid off and put it under the microscope. Took about 16 overlapping photos, then stitched the photos together and traced the logic. It was a slightly modified Booth's algorithm job, but our implementation had to be a bit different as the Fast process didn't allow multiemitter transistors which were common in LS gates.
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As an aside I was recently working on a 4800 bps leased-line modem unit that does digital signal processing using an '558 parallel multiplier and a couple of 2901 ALU slices. Controlled by a set of microcode PROMs sequenced by 3 2911s. Fascinating bit of design.