On Wed, 5 Aug 2009 07:54:23 -0500, McKown, John <[email protected]> wrote: > Yes, but I vaguely remember some system that we studied > in college which had "writable control storage"
Yep. Back In The Day a pal and I invented an alternate instruction set for the Varian V-73 we had at hand. The major improvement of ours over the native "620-F" instruction set was base/barricade relocation. In our instruction design we borrowed a couple of things from the S/360 set which didn't work out so well. EXecute in particular was a real PITA; it complicated the instruction fetch sequence in unpleasant ways for little obvious benefit. Another pal jumped in and microcoded the I/O instructions, and while he was in there he rewrote my instruction fetch sequence (which I had formerly been proud of), cutting its size in *half*. I was irritated, but you had to give him props. Code-bumming those long microwords is an art form. -- David Andrews A. Duda and Sons, Inc. [email protected] ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: GET IBM-MAIN INFO Search the archives at http://bama.ua.edu/archives/ibm-main.html
