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From: eggert@sdcrdcf.UUCP
Newsgroups: comp.arch
Subject: D-machine helped spawn RISC
Message-ID: <4782@sdcrdcf.UUCP>
Date: Sun, 6-Sep-87 00:40:07 EDT
Article-I.D.: sdcrdcf.4782
Posted: Sun Sep  6 00:40:07 1987
Date-Received: Sun, 6-Sep-87 20:18:02 EDT
Reply-To: eggert@SM.Unisys.com (Paul Eggert)
Distribution: world
Organization: Unisys (nee Burroughs nee SDC) Santa Monica
Lines: 14

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!