Article View: comp.arch
Article #20408Re: Re: MicroVAX emulation
From: Stan Lackey
Date: Tue, 21 Mar 1989 15:19
Date: Tue, 21 Mar 1989 15:19
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1882 bytes
In various articles various writers write:
>> > OK ... so you take a performance hit on an Ultrix uVAX II. Fine you say.
>> Wait a minute. I never said that taking a performance hit would be OK.
>> Similar things happen with floating point [example about 68000's & 68881's
>> & Lightspeed C deleted for brevity]
>
>The example is not applicable for 2 reasons.
>
>1) The "68000 architecture" does not include FP instructions. The
> "VAX architecture" DOES include the string instructions.
True statements. HOWEVER, the MICROvax architecture does NOT include
string instructions, other than MOVC3 (and MOVC5?). Some DEC-supplied
software includes emulation to ease the transition. Generating the
in-line emulation using a reduced instruction set is NO PROBLEM, right?
And gets better performance too? :-)
>> > Until DEC is prepared to supply free and unencumbered source code
>> > for the instruction emulation routines, the uVAX II cannot be said
>> > to implement the VAX architecture!
1. The uVAX is NOT said to implement the VAX architecture.
2. MIPS, AMD, Intel, Motorola, Sun, etc. don't do your work for you either.
I don't understand why it is OK for the RISC suppliers to supply
reduced instruction sets, but if DEC does it it's evil.
-Stan
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Path: arc1-ca.pugleaf.net!utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!bbn!bbn.com!slackey From: slackey@bbn.com (Stan Lackey) Newsgroups: comp.arch Subject: Re: Re: MicroVAX emulation Message-ID: <37515@bbn.COM> Date: 21 Mar 89 15:19:41 GMT References: <807@microsoft.UUCP> <92634@sun.uucp> <13322@steinmetz.ge.com> <1133@auspex.UUCP> <12000@haddock.ima.isc.com> <1368@husc6.harvard.edu> <679@scaup.cl.cam.ac.uk> <12035@haddock.ima.isc.com> <687@scaup.cl.cam.ac.uk> Sender: news@bbn.COM Reply-To: slackey@BBN.COM (Stan Lackey) Organization: Bolt Beranek and Newman Inc., Cambridge MA Lines: 24