Path: utzoo!utgpu!cunews!cognos!alzabo!andras From: andras@alzabo.uucp (Andras Kovacs) Newsgroups: comp.arch Subject: Re: The CPU with 3 brains Message-ID: <1990Nov8.063034.6933@alzabo.uucp> Date: 8 Nov 90 06:30:34 GMT References: <42737@mips.mips.COM> <1990Nov4.014901.23819@zoo.toronto.edu> <2841@crdos1.crd.ge.COM> Reply-To: andras@alzabo.UUCP (Andras Kovacs) Organization: Brian's XENIXlings, Ottawa, Canada Lines: 45 In article <2841@crdos1.crd.ge.COM> davidsen@crdos1.crd.ge.com (bill davidsen) writes: >In article pcg@cs.aber.ac.uk (Piercarlo Grandi) writes: > >| Except for oddities like the 860 and 960, isn't the 486 still designed >| to be almost binary compatible with the 8008? Sigh! > > As far as I know the 80486 and 8008 are completely compatible at the >level of the first two digits of the part number. The instruction set is >100% diferent, so the only binary compatibility is that they both will >read ones and zeros. Although Mr. Grandi was somewhat lax in his wording, it is a fact that the 8086 was designed to be 'object level compatible' with the 8080 - I don't know about the 8008. The term means that a programmer (coder? software engineer? :-)) who had experience with the 8080 (supposedly in an embedded-controller context) would be able to 'translate' any existing code to the 8086 rather quickly + be able to use the added benefits of the 16-bit architecture. (Think about dedicated registers: A-AX (accu.), B-BX/C-CX (pointer, counter), D-DX/E-??? (gen. purpose 16bit reg.), HL/BP-SI-DI (dedicated pointer regs.)). So in this sense, the 486 indeed propagates an outdated programming model which was intended primarily for the controller market - and kept certain compatibility with the 8080. The problem did come with the IBM PC and its 8088 - an IBM dude said in Byte's 15th anniversary issue that they picked the 8088 as the CPU for the IBM PC 'cause THEY HAD DEVELOPMENT EXPERIENCE WITH THE 8080 AND IT'S 8 BIT PERPHERALS! (NB the IBM PC was done by Entry Systems Division of IBM - they basically wanted an 'intelligent RJE' which can run programs on it's own). How comes that IBM doesn't try to conquer the workstation market based on Intel 486/586/??????86 ? Because they know (I assume) that the 486/386/286/8086/8080 programmer's model SUCKS, and although with better manufacturing technology they can speed it up (386/486), it's doesn't really worth the effort except providing blindingly fast f*****g DOS machines! Which is fine by me, I would like to see all the world's x86es recalculating huge Lotus 1-2-3 spreadsheets in 1 zillionth of a second and let me fiddle with my cute RISC processor to solve 'real problems'! (Which are real problems? I don't know, I am just an immigrant... :-)) I am not damning the emergence of the IBM PC - that sucker indeed did give power to the people. But I loathe the x86 line after meeting Miss RISC and I would like to quote someone's .signature (can't recall whose): "To understand and appreciate a 386 is mutually exclusive." (Sorry for the long article :-)) -- Andras Kovacs andras@alzabo.UUCP