12 Nov
2005
12 Nov
'05
2:48 p.m.
The story I hear was that the System/3 was built by a CE in his home using
salvaged parts and adopted by IBM as a product. I have no references to
prove it. If so, then there was no logic to the decision. The 360 was just
way too big a design to strip down as the comments on the model 20 show. The
sys 3 was for really small offices.
IMHO the most bizarre thing was the twinax cabling. That line and some Wang
systems were the only ones I ever saw. Not being a hardware guy I have no
idea if there is any advantage for twinax over coax.
Gil
...
...
While the S/3
instruction set bears certain similarities to
the S/360,
I've wondered what IBM's logic was for
making it so
different from the
S/360. I doubt that it was technical--the 360/20
was far more
brain-dead than the
S/3 and customers still used them, in spite of the crippled
instruction set.
The S/3 line was...special. There are only 30 or so instructions in the whole set,
yet a
number of them are for complex string handling (kind of
inpressive for a non-microcode machine to do string inserts,
actually). There are no simple byte level instructions -
everything that goes thru the ALUs are strings, basically.
Everything is a string. Thw world is a string to an S/3.
And yes, the S/3 is a real variable word length machine! Yes,
you can add two 569 byte integers with one instruction!
William Donzelli
aw288 at osfn.org