The hardware designer Jim Mulder quotes says <begin extract> I assume the AMODE(31) and AMODE(64) he is referring to only affects the addressing mode, but the exact same instruction sequences are used in both cases. If different code sequences are being used, then all bets are off. </end extract>
thus disposing neatly of a straw man. It is of course possible to write snippets of code using only modal instructions in such a way that "the exact same instruction sequences are used in both cases"; but it is almost never appropriate to do so; and I did not do, or say that I had done, that. Let me also take this opportunity to respond to Kenneth Wilkerson, who has a weakness for the sententious. He informs us that algorithms are more important than code sequences. I think it may be conceded out of hand that binary search is faster than linear search and again that linear search of an ordered list implemented as a glb-seeking or lub-seeking one followed by a test of any bound found for equality is faster that the two-tests-per-iteration schemes my students sometimes come up with. (Knuth pointed this out many years ago.) More generally, logarithmic-time schemes are faster than polynomial-time ones, etc., etc . It is nevertheless possible to implement algorithms correctly but badly, and coding effects and algorithmic effects are often difficult or even impossible to disentangle. As sometimes happens here, we are talking at cross purposes and generating more heat than light in doing so. John Gilmore, Ashland, MA 01721 - USA ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN
