20 Oct
1998
20 Oct
'98
5:46 a.m.
Motorola claims to have started shipping ECL integrated
circuits in 1962.
Why were people still building computers using discrete transistors for
years after that? Many of the high-end computers used discrete
implementations of non-saturating logic that was very similar to ECL.
Most of the early IC production went into defense electronics, especially
missile guidance computers. Even after IC's were commercially available,
they were quite expensive, even in production quantities.
IBM continued to ship new SLT-based designs when their competitors were
moving to IC's, and they were the target of some marketing hype as a
result. However, IBM had tuned the circuit design, packaging and
manufacturing processes for SLT so well that they could get more
performance per dollar out of SLT than anyone could get out of IC's.
(Source: Pugh, Johnson and Palmer, "IBM's 360 and Early 370 Systems", MIT
Press.)
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John Dykstra jdykstra(a)nortel.com
Principal Software Architect voice: +1 651 415-1604
Nortel (Northern Telecom) fax: +1 612 932-8549