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Path: utzoo!dciem!nrcaer!cognos!roberts
From: roberts@cognos.uucp (Robert Stanley)
Newsgroups: comp.arch
Subject: Re: Wirth's "challenge" (was Re: RISC)
Message-ID: <1883@cognos.UUCP>
Date: Sat, 28-Nov-87 16:17:20 EST
Article-I.D.: cognos.1883
Posted: Sat Nov 28 16:17:20 1987
Date-Received: Tue, 1-Dec-87 05:24:14 EST
References: <902@mips.UUCP> <1775@cognos.UUCP> <5157@columbia.edu>
Reply-To: roberts@cognos.UUCP (Robert Stanley)
Organization: Cognos Inc., Ottawa, Canada
Lines: 27

In article <5157@columbia.edu> dupuy@amsterdam.columbia.edu
	   (Alexander Dupuy) writes:

>Perhaps I'm misunderstanding you, but do you mean to say that the 801 had a
>360/370 emulation mode?  My understanding was that the PL/I (actually, PL.8)
>compiler generated machine-independent intermediate code, which was transformed
>by a later pass into 801 machine code.  A back-end to convert the intermediate
>code into 370 machine code existed ...

I stand corrected - apologies to any misled by my earlier posting.  Alexander
Dupuy is quite right that intermediate code was output and then post-processed
in various ways, including register allocation optimization (by graph colouring)
and code generation for specific target machine.  Amazing how quickly unused
knowledge decays!

>I have no idea if any of these things ever saw the light of day outside IBM

Not in the form originally worked with in Building 801.  However, the same RISC
architecture became both the RT PC and the heart of a number of key pieces of
the big mainframe systems.  I have no idea what is currently used to program
such equipment.

-- 
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