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Old 2020-07-06, 11:04   #12
kriesel's Avatar
Mar 2017
US midwest

33·263 Posts

Originally Posted by R.D. Silverman View Post
The clock rate was slow [only 10 KHz] because the board was built with prototype wirewrap. [proof of concept]
Astonishingly slow. I knew folks who hand wire wrapped custom designed full size Unibus boards for VAX systems populated with ECL chips, ~1984, to do specialized image processing and real-time machine control at 2 microsec or better, far faster than the VAX 11/750 computer could process by itself. Those boards were the area of a closed pizza box and ran at 30Mhz IIRC. (It controlled a 3kw electron beam making little raster patterns to produce xrays, all aimed at a live human subject's mouth. If control was too slow, or hung, the focused electron beam would damage the thin tungsten target and let cooling water into the vacuum system, causing downtime for repair of weeks or more for a unique national shared speech research faciility.)
The best feature of wire wrap for prototyping was a connection change could be made in about a minute. Comments here about various techniques are interesting.

The same small group was involved in early design of at least one of the less costly VAXes, the 730 I think. IIRC both systems used AM29xx bit slice processors.

Last fiddled with by kriesel on 2020-07-06 at 11:18
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