CDC 6600 - Why so awesome?

Swift Griggs swiftgriggs at
Wed Jun 22 10:32:23 CDT 2016

On Tue, 21 Jun 2016, Chuck Guzis wrote:
> > - It had some wicked cool "demos", to cop a C64 term. (ADC, PAC, EYE)
> Those were mostly toys to amuse the CEs, like the baseball game BAT.

I was trying to find some video of one of those actually running. I wanted 
to see how the "calligraphic displays" painted the graphics. Do you happen 
to know why they went with two displays like that? Did the two have 
different purposes?

> Chess 3.0 was implemented on Northwestern's machine and probably was the 
> first computer chess program of note.  This was before kids thought that 
> computer games were *cool*.  I never developed a taste for computer 
> gaming.

Most folks I know who were in their 20s or 30s in the 60s or 70s didn't, 
either. However, computer games were the "hook" that got a lot of people 
like me interested in computing as children. I instantly became more 
interested in creating the games, not just playing them. I've known a lot 
of others with the same sort of instincts.

> Much of the architectural concept was shared with IBM 7030 STRETCH 
> (another system worth researching).

Hmm, I've never heard of it. I'll check it out. Thanks. 

> > - It wasn't DEC and it wasn't IBM and it was faster than both when it hit 
> >   the street? 
> With a 10 MHz clock.


> It had several *cool* OSes, but really only two major ones for general 
> consumption (Special Systems Dvision had several more).  SCOPE (later 
> NOS/BE), pretty much initially a PP-resident OS based on the old 
> Chippewa Operating System--and NOS (was KRONOS, originally MACE),

I tried to find some info on SCOPE, but it's very sparse. Did it have an 
interactive command line? What was your main "interface" to the OS? 

> started as a "bootleg" project by Greg Mansfield and (Dr.) Dave 
> Callender at Arden Hills.  (MACE stood for "(Greg) Mansfield's Answer to 
> Customer Engineering".

Lots of great and interesting operating systems start as a reaction to the 
status quo or some idea they find abhorrent. UNIX and many variants 
certainly have. Ie.. Ken & Dennis working on side-projects while bored and 
demotivated by Multics, BSD guys reacting to AT&T clamping down, Linus 
reacting to his profs, Theo forking NetBSD, I could go on and on...

UNIX: Born in rebellion.

> Most batch programs written for SCOPE would run fine on MACE with few, 
> if any, modifications.

Did Control Data sell both or was one from an alternative vendor?

>  In retrospect, CDC keeping two operating systems (SCOPE was part of CPD 
> in Sunnyvale, while KRONOS stayed home in Arden Hillls) was probably a 
> strategic blunder, since much duplicate effort was wasted.  Eventually, 
> the two were merged into NOS (for Network Operating System).

I found this PDF:

It's interesting to me because of how "different" everything is. I'm not 
well versed in mainframe operating systems. It's interesting.

> There aren't any alignment issues, since the CPU was only 
> word-addressable.  This was when a character was 6 bits (think IBM 709x, 
> UNIVAC 1100, etc.)  So a word with 10 characters was logical.

I figured it was something like that, but I'm so used to 8-bit bytes and 
such. It takes a minute to adjust my thinking to a different base, but 
it's not that hard.

> Given that PP words 12 bits (5 to a CM word) and there were 10 PPUs, 
> each executing at a speed 1/10th the CPU, it had a very pleasant sort of 
> symmetry.

I suppose it doesn't matter as long as things factor out properly: no 

> COMPASS was indeed advanced for its time, but then so was OS/360 
> assembly language.  Given that assembly was the lingua franca of system 
> programming, assemblers had to be good.  Most of the readability was due 
> to attention to detail by the programmer, not any particular language 
> feature.

Well, the sample code I could find was particularly well put together by 
someone who knew they were doing. I'm a pretty poor ASM programmer, since 
the only one I ever put much effort into was for the M68k (which is really 
easy compared to some).  I've got a big crush on MIPS ASM but I never was 
any good with it. C ruined me. :-)

> > ... 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. 
> Where did you find that?  I've never heard of such an instruction.

I was mistaken, it's only a control statement for COMPASS. It's actually 
in the PDF manual I was just looking at. It's used to "preserve a user's 
ECS field length between job steps."


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