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From: haynes@ucscc.UCSC.EDU (99700000)
Newsgroups: comp.arch
Subject: Re: 3rd party OS
Message-ID: <3707@saturn.ucsc.edu>
Date: 10 Jun 88 15:47:19 GMT
References: <3327@phri.UUCP> <63900017@convex> <321@babbage.acc.virginia.edu> <11202@steinmetz.ge.com>
Sender: usenet@saturn.ucsc.edu
Reply-To: haynes@ucscc.UCSC.EDU (Jim Haynes)
Organization: California State Home for the Weird
Lines: 50

In article <11202@steinmetz.ge.com> davidsen@crdos1.UUCP (bill davidsen) writes:
>In article <321@babbage.acc.virginia.edu> mac3n@babbage.acc.virginia.edu (Alex Colvin) writes:
>
>| Uh...  That's Dartmouth's DTSS, or GE's Mark <some roman numeral> that
>
>  DTSS is (was) interesting in that it is one of the systems which
>allows only one processor to handle interrupts. I believe that all of
>the other systems for this cpu use all processors for all functions.
>
I don't know about the later Honeywell machines, but on the GE-635 it is
the hardware, not the software, that requires one processor to handle all
the interrupts.  I have a mental picture of a rotary switch, but my
memory isn't very good.  The Burroughs B5500 also had this "feature",
in this case controlled by a toggle switch that designated which of two
processors was to handle the interrupts.  The Burroughs D-825 (military
machine, different division of Burroughs) supposedly did let any processor
handle the interrupts so you really could just switch off any unit and
the system would continue operating.  On the B5500 you could switch off
any I/O channel if you could catch it between operations.  Or you could
switch off any I/O channels so long as you left at least one, and you
could switch off any memory except the one at address zero, and you
could switch the second processor on or off, and then reboot and you
were running again.  Which was quite a boon contrasted with some
competing machines that were totally down when any part was down.
>  We were visiting Dartmouth back in ~1969 to see this wonder work. One
>  ...
>  While we were there we looked at the "RACE file." This was a monster
>box full of small Mylar cards. On demand a card would be selected and
>slid down to the business end, where it would be wrapped around a drum
>and read as a small drum device. I believe the transfer rate was 72 bits
>every 7us, or about 10 meg.
Gosh, I didn't realize G.E. ever let one of those things out of the plant.
The drive was actually made by RCA, and inspired such confidence in all
who saw it that it was universally called the "chicken plucker".
> This was screaming in the days of 200ms
>access disks. Later GE built the 270 disk, a head per track job. They
>cost a bunch but were really fast.
Actually a Burroughs disk OEMed to GE.  GE's previous disk line was one
of those things with 3-ft diameter horizontal disks, each with its own
separate head actuator.  This was a product originally developed for the
GE 200 computer line, then ported to the 400-line where it was almost
adequate, and then further ported to the 600-line which beat it to pieces.
>-- 
>	bill davidsen		(wedu@ge-crd.arpa)
>  {uunet | philabs | seismo}!steinmetz!crdos1!davidsen
>"Stupidity, like virtue, is its own reward" -me


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