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From: henry@utzoo.UUCP (Henry Spencer)
Newsgroups: net.arch
Subject: Re: Re: Re: RISC (really on multiplication d
Message-ID: <5825@utzoo.UUCP>
Date: Thu, 25-Jul-85 14:30:52 EDT
Article-I.D.: utzoo.5825
Posted: Thu Jul 25 14:30:52 1985
Date-Received: Thu, 25-Jul-85 14:30:52 EDT
References: <149@mips.UUCP> <600005@pbear.UUCP> <493@mmintl.UUCP> <233@weitek.UUCP>, <1202@sjuvax.UUCP>
Organization: U of Toronto Zoology
Lines: 22

> > The Decsystem-10 & 20 has an instruction IMUL which does exactly what you
> > want. It Multiplies a 36bit value by another 36 bit value and gives a 36
> > bit result. They also have a divide which divides a 36 bit number.
> 
> For comparison and elucidation, so do:
> 
> 	VAX
> 	PDP-11
> 	National 32016 and family
> 	Motorola 68000, 68020, 6800, 6809, ...
> 	Zilog Z8000
> 	Z80
> 	Intel 8086, 80186, 82086

From personal experience, I can assure you that the PDP-11 and the 6809
most definitely do not.  And the 6800 has no multiply instruction at all.
I don't think the Z80 does either.  The 68000 has 16x16->32, but neither
32x32->32 nor 16x16->16 that I remember.  And my (admittedly dim) memory
of the Z8000 is that its multiply instructions yield double-width results.
-- 
				Henry Spencer @ U of Toronto Zoology
				{allegra,ihnp4,linus,decvax}!utzoo!henry