Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Path: utzoo!mnetor!uunet!husc6!rutgers!im4u!ut-sally!utah-cs!utah-gr!uplherc!esunix!bpendlet From: bpendlet@esunix.UUCP (Bob Pendleton) Newsgroups: comp.arch Subject: Re: D-machine helped spawn RISC Message-ID: <475@esunix.UUCP> Date: Tue, 8-Sep-87 10:53:12 EDT Article-I.D.: esunix.475 Posted: Tue Sep 8 10:53:12 1987 Date-Received: Fri, 11-Sep-87 07:18:45 EDT References: <4782@sdcrdcf.UUCP> Organization: Evans & Sutherland, Salt Lake City, Utah Lines: 41 in article <4782@sdcrdcf.UUCP>, eggert@sdcrdcf.UUCP (Paul Eggert) says: - -In article <288@tropix.UUCP> mjl@tropix.UUCP (Mike Lutz) writes - - ... the B1700 was a pleasure to work with at the microcode level (and - anyone who has done serious microprogramming knows what an amazing - statement that is!) While not a "RISC" machine, the B1700 was - optimized for emulation, and the pieces just fit together well.... - -What irony! David Patterson, Mr. RISC, wrote his PhD thesis at UCLA in 1975 on -formal verification of microcode for the D-machine (as Lutz says, really the -Burroughs 1700). Partly because of the D-machine's pleasantness, Patterson was -surprisingly successful. But the aggravation of verifying microcode convinced -him that microcode causes more problems than it cures; he turned to the design -of machines that don't need microcode. So that unlikely couple, formal -verification and dynamically microcodable CISC, helped spawn RISC! What a wierd coincidence! I just happen to have copies of David Pattersons papers, "Strum: Structured Microprogram Development System for Correct Firmware" IEEE Transactions on Computers, Vol. @-25n No 10, October 1976, and "An Experiment In High Level Language Microprogramming and Verification" CACM, October 1981, Volume 24, Number 10, sitting on my desk. I was rereading them late last week. I worked on the B1700 at the University of Utah in the early 1970s and have been telling people for several years that I thought RISC looked like vertical microcode "done right." If what you say is true, then I was right. Imagine that. In five years I expect that RISC will be passe, that WISC ( wide instruction set computers ) will be all the rage. WISC will be horizontal microcode "done right." It will have all the advantages of RISC, but WISC machines will run faster and cost less. We haven't abandoned microcode, we've just let it out of the closet. Bob Pendleton -- Bob Pendleton @ Evans & Sutherland UUCP Address: {decvax,ucbvax,ihnp4,allegra}!decwrl!esunix!bpendlet Alternate: {ihnp4,seismo}!utah-cs!utah-gr!uplherc!esunix!bpendlet I am solely responsible for what I say.