> On Jul 15, 2015, at 2:14 PM, Chuck Guzis <ccl...@sydex.com> wrote: > > On 07/15/2015 10:48 AM, Jay Jaeger wrote: >> 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.
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