CDC 6600 - Why so awesome?
swiftgriggs at gmail.com
Tue Jun 21 16:06:02 CDT 2016
To my sorrow, I'd never heard of the CDC 6600 and I barely knew who
Control Data was (whippersnapper, I know). I see a lot of traffic about
them on the list and I went out to discover "why so cool?" Wikipedia and
other spots talk about the features, but I'm trying to understand from
folks who put hands to the metal, why they liked them so much.
I'm a total igmo concerning this bit of kit. Is this about right?
- It has dual "calligraphic" displays. Geeze! Very freakin' cool
- It was RISC nearly before folks could even articulate the concept
- It had some wicked cool "demos", to cop a C64 term. (ADC, PAC, EYE)
- It wasn't DEC and it wasn't IBM and it was faster than both when it hit
- It has a cool OS? Dunno. Not much info on "SCOPE"
- Made in the USA baby! Back when we actually made things.
- It used odd sized (by todays standards) register, instruction, and bus
sizes. 60 bit machine with 15/30 bit instructions. But, didn't it cause
a bunch of alignment issues for you ?
I dug into the CPU instructions for about 20 minutes and it was actually
pretty straightforward. The so-called "COMPASS" ASM code was oh-so-cool. I
can't believe they had so many of the features now considered "modern" or
"clever" (at least by me) in the 1960s! This code:
... Is super-readable, in fact, probably a bit more than several
much-newer dialects on different platforms. There was one instruction
"PROTECT" I found pretty interesting, too. Was that similar to noodling
with the control registers CR0, CR2, CR3, and CR4 on x86 to mark memory
protection from segmentation violations? I remember that being the
protection mechanism on my 386 SX/16 (and I remember it being a PITA),
however the COMPASS "way" looks much easier/cooler and must have some
hardware assistance to do that so easily.
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