15 Jul
2015
15 Jul
'15
11:58 a.m.
On Jul 15, 2015, at 2:14 PM, Chuck Guzis <cclist at
sydex.com> wrote:
On 07/15/2015 10:48 AM, Jay Jaeger wrote:
Correct: http://www.cs.utexas.edu/users/EWD/transcriptions/EWD00xx/EWD37.html
I don?t know what he thought of the 1401. He did reject the 7040 when it was proposed to
the university as its main computer. That analysis is in
http://www.cs.utexas.edu/users/EWD/transcriptions/OtherDocs/NN041.html (in Dutch). When
comparing with the machine they ended up with (Electrologica EL-X8) I have to concur with
his judgment, not that the EL-X8 is flawless, but in key spots it gets things right that
IBM gets wrong.
paul
Lots of machines supported variable length
operands (like the machine
you reference in the link, IBM S/360, Burroughs, etc. etc. However,
machines with variable length instructions not split into any kind of
word boundary are not as common.
Sure, but that doesn't mean that they didn't exist. As a matter of fact, the
machine I cited was *bit*-addressable. That doesn't imply that any datum was absolved
of some sort of alignment. But yes, you could have bit fields overlapping word
boundaries--let's see your 1410 do that...
I really don't see much of a fundamental distinction between the 1401, 1410, 7080 or
1620 or any other variable word-length machine of the time. One really have to ask
oneself "why variable word-length?" when it costs so much in terms of
performance. I believe that it's mostly because memory was very expensive and it was
viewed as a way of coping with that issue.
FWIW, Dijkstra disliked the 1620 immensely. I don't recall his opinion of the 1401.