Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!swrinde!zaphod.mps.ohio-state.edu!wuarchive!julius.cs.uiuc.edu!ux1.cso.uiuc.edu!uxa.cso.uiuc.edu!msp33327 From: msp33327@uxa.cso.uiuc.edu (Michael S. Pereckas) Newsgroups: comp.arch Subject: Re: The CPU with 3 brains---486 compatibility with 8008 Message-ID: <1990Nov6.223738.13265@ux1.cso.uiuc.edu> Date: 6 Nov 90 22:37:38 GMT References: <42737@mips.mips.COM> <1990Nov4.014901.23819@zoo.toronto.edu> <2841@crdos1.crd.ge.COM> Sender: news@ux1.cso.uiuc.edu (News) Organization: University of Illinois at Urbana Lines: 27 In <2841@crdos1.crd.ge.COM> davidsen@crdos1.crd.ge.COM (Wm E Davidsen Jr) 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. I don't know anything about the 8008, but I know that although the 8086 is not binary compatible with the 8080, it is similar enough that porting assembly code is (I mean, was) supposed to be so easy that it could be done automatically. The 80486 is (of course) binary compatible with the 8086. This is why you can run Wordstar 3.0 on your 486 box. (That may well be better than whatever the latest version is.) (A few years ago, I tried (for laughs) running Wordstar 3.0 on a 20 MHz 386. It was no faster than on a 4MHz Z80. Amazing.) :-) -- Michael Pereckas * InterNet: m-pereckas@uiuc.edu * just another student... (CI$: 72311,3246) *Jargon Dept.: Decoupled Architecture--sounds like the aftermath of a tornado*