Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: version B 2.10.2 9/18/84; site sdcrdcf.UUCP Path: utzoo!watmath!clyde!burl!ulysses!mhuxr!ihnp4!houxm!whuxl!whuxlm!akgua!sdcsvax!sdcrdcf!darrelj From: darrelj@sdcrdcf.UUCP (Darrel VanBuer) Newsgroups: net.micro Subject: Re: Need a microprogramming consultant! Message-ID: <1820@sdcrdcf.UUCP> Date: Wed, 6-Mar-85 13:32:11 EST Article-I.D.: sdcrdcf.1820 Posted: Wed Mar 6 13:32:11 1985 Date-Received: Sun, 10-Mar-85 05:15:18 EST References: <1272@drux3.UUCP> <501@ahuta.UUCP> <184@redwood.UUCP> Reply-To: darrelj@sdcrdcf.UUCP (Darrel VanBuer) Organization: System Development Corp. R+D, Santa Monica Lines: 23 Summary: Another reason to have microprograms in RAM (besides reducing cost of bug fixes) used by a number of companies (notably those making Lisp machines) is tailoring the instruction set of the machine to the application E.g. the Xerox Dolphin can be an Alto, a Lisp machine, a Smalltalk machine or a Mesa machine, depending on which microcode is (dynamically) loaded. The Alto code is straight emulation to exploit a preexisting operating system, the others implement an abstract machine model tailored to the language. The Dolphin has only a single processor, but has a small read-only microprogram memory which contains just enough to bootstrap microcode from the disk or Ethernet. Some computers and vendors provide tools for user microcode (usually for augmenting the instruction set rather than replacing it), a few even implement virtual memory microstores! -- Darrel J. Van Buer, PhD System Development Corp. 2500 Colorado Ave Santa Monica, CA 90406 (213)820-4111 x5449 ...{allegra,burdvax,cbosgd,hplabs,ihnp4,orstcs,sdcsvax,ucla-cs,akgua} !sdcrdcf!darrelj VANBUER@USC-ECL.ARPA