ron at ronnatalie.com
Sat Sep 13 08:18:22 AEST 2014
When a PDP-11 instruction is dumped in octal, it's pretty easy to read. The bottom six, nine, or twelve bits are the operand (three bits for addressing mode, three bits for register).
While I'm a bit out of practice these days, I'd certainly read through a few octal dumps like that.
Octal isn't a stretch for the Cray. Cray was begat by the old CDC mainframes, the last of which was the 7600 (BRL got the LAST 7600 ever built, they held the line open for us.
It wasn't decommisioned until about 1987. The CDC had a 60 bit word size.
I somehow to my chagrin got responsible for all the comm gear for that fed the beast. As we were getting ready to decommission it I had all these "surplus tags" that I was attaching
to all the multiplexors and modems and the like. I amusingly taped one up on the corner of the main CPU cabinet. The people running the data center weren't amused.
The room where the 7600 was held received one of the few Denelcor HEP systems (which was designed for BRL). Mike Muuss's group (of which I was a part), ported UNIX to run
on that beast. It ran for a short while before it was replaced with a Cray X/MP (one originally slated to go to Apple but we preempted their order). Right before I left BRL I put my signature
to the Cray 2 procurement.
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