AW: When did Memory- and IO Protection Emerge (Esp. in Minis)?

Chuck Guzis cclist at
Thu May 5 00:29:12 CDT 2016

On 05/04/2016 10:10 PM, Curious Marc wrote:
> For the fun of the argument: I was privileged enough to see Carl's
> IBM 1130, and to my newbie eye, it may justifiably earn the title of
> "small" computer, when compared to its brethren of the time. But it
> would never occur to me to call it a mini! It's quite a biggie
> computer actually. Heavy stuff, forklift or winch needed to put it
> safely in the truck as I recall. Then I thought our IBM 1401 was big.
> That's when more knowledgeable people pointed me to the IBM 7090. Now
> that's *really* big. And then you have SAGE. Now that's huge. Or
> insane, depending on your engineering point of view :-).

On the other hand, the PB250 was contained in a single 5' rack (table
model), ran off of a single 15A 120V circuit and weighed a bit over 100
lbs.  I'd call it a minicomputer if it weren't for the fact that it was
brought out around 1961.  22 bit words.  Up to about 16KW in the box;
magnetostrictive delay line memory, bit-serial ALU.  IIRC, lotsa diodes,
but comparatively few (ca. 300-400) transistors.


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