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

Jon Elson elson at
Thu May 5 12:06:34 CDT 2016

On 05/05/2016 12:29 AM, Chuck Guzis wrote:
> 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.
Another "mini" was the Bendix G-15, 300+ vacuum tubes, 3000 
diodes and a drum memory.
Certainly no memory protection on it.  It was the size of a 

And another, the LINC, discrete transistor machine, 2K 
12-bit words and a software driven screen, so it was 
actually interactive. Storage was LINCtapes, the predecessor 
to DECtapes.  Fit in a single 5' relay rack, with a console 
on a desk.


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