Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!ames!uakari.primate.wisc.edu!ginosko!uunet!image.soe.clarkson.edu!news From: nelson@sun.soe.clarkson.edu (Russ Nelson) Newsgroups: comp.sys.ibm.pc Subject: Re: Why is DOS limited to 640K? Message-ID: Date: 16 Oct 89 03:35:08 GMT References: <8909270503.AA28536@euler.Berkeley.EDU> <10253@cbnews.ATT.COM> <1464@redsox.bsw.com> Sender: news@sun.soe.clarkson.edu Reply-To: nelson@clutx.clarkson.edu Organization: Clarkson University, Potsdam NY Lines: 24 In-reply-to: campbell@redsox.bsw.com's message of 15 Oct 89 22:36:43 GMT In article <1464@redsox.bsw.com> campbell@redsox.bsw.com (Larry Campbell) writes: PC-DOS -- that is, MS-DOS as implemented by IBM on the PC -- is limited to 640K because IBM reserved the addresses above 640K for device adapters and the ROM BIOS. Actually, Bill Gates has admitted to allocating "only" 640K to system ram. Of course, if they realized that they had a winner, they would have designed the thing rather than banging some Intel parts together. This in itself is not so horrible as is the fact that people *had* to access display memory in order to get any performance out of the machine. If Bill had started discouraging this with DOS 2.0, we could have eventually wound up with a machine-independent OS. The fact that he didn't tells me more than a little about his technical expertise. Apple got it right with the MacIntosh. Give the developer a reasonable software interface, leave the hardware interface undocumented, and keep changing the hardware so that ill-behaved programs keep breaking. -- --russ (nelson@clutx [.bitnet | .clarkson.edu]) Live up to the light thou hast, and more will be granted thee. A recession now appears more than 2 years away -- John D. Mathon, 4 Oct 1989.