Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Path: utzoo!mnetor!uunet!husc6!necntc!ima!johnl From: johnl@ima.ISC.COM (John R. Levine) Newsgroups: comp.sys.ibm.pc Subject: Re: What Intel had that nobody else did when PC was designed Message-ID: <650@ima.ISC.COM> Date: Thu, 13-Aug-87 18:46:28 EDT Article-I.D.: ima.650 Posted: Thu Aug 13 18:46:28 1987 Date-Received: Sat, 15-Aug-87 10:45:26 EDT References: <234@etn-rad.UUCP> <4680001@hprndli.HP> <3233@zen.berkeley.edu> <294@octopus.UUCP> <595@cup.portal.com> Reply-To: johnl@ima.UUCP (John R. Levine) Organization: Not enough to make any difference Lines: 42 Summary: a 16 bit cpu with an 8-bit bus In article <595@cup.portal.com> Isaac_K_Rabinovitch@cup.portal.com writes: >pete@octopus.uucp says: >>(a bunch of reasons why IBM was never interested in CP/M compatibility) >Actually, IBM offered *three* OSs with the first PCs, including CP/M. But >MS-DOS was half the price of the other two. What clinched it for MS-DOS >was all those applications developers writing for it. I've always heard that the plan for the PC included a Z80 processor until late in the design process. Then IBM realized that a better processor would distinguish them from the other zillion mediocre CP/M boxes out there. Only Intel had a part, the 8088, that they could plug into their 8-bit designs without having to completely redo all of the peripherals for a 16-bit bus. The 68008 was nowhere near ready in 1980. Rumor also has it that IBM was under the impression that MS-DOS was fully compatible with CP/M-80 until somewhat after the PC was shipped. I can see the conversation now: IBM: Is this system you're offering us 100% compatible with CP/M on the Z80? Bill Gates: It doesn't make sense to ask, since the 8088 isn't binary compatible with the Z80. IBM: Our marketing surveys tell us that any system we sell has to be 100% CP/M compatible to sell well. Gates: Then why are you using an 8088 which won't run Z80 code? IBM: Our marketing surveys tell us that a more powerful processor will gain us market share. Gates: But no 8088 operating system can be 100% Z80 compatible. IBM: Well, we can't sign a contract to buy 500,000 copies of your operating system unless it's 100% CP/M compatible. Gates [no fool]: Oh, in that case, it's 100% CP/M compatible. -- John R. Levine, Cambridge MA, +1 617 492 3869 { ihnp4 | decvax | cbosgd | harvard | yale }!ima!johnl, Levine@YALE.something The Iran-Contra affair: None of this would have happened if Ronald Reagan were still alive.