Path: utzoo!attcan!uunet!ncc!alberta!access!edm!rroot From: rroot@edm.UUCP (uucp) Newsgroups: comp.arch Subject: Re: Is the Intel memory model safe from NO-ONE ?!? Message-ID: <3108@edm.UUCP> Date: 12 May 88 08:55:18 GMT References: <2429@louie.udel.EDU> Organization: Unexsys Systems, Edmonton,AB. Lines: 20 From article <2429@louie.udel.EDU>, by rminnich@udel.EDU (Ron Minnich): > In any real program, there are a large number of legal regions, which > you don't want to get confused. Flat address space machines do not help . . . . > segments help enforce. In a flat address space, two arrays of structures > butted against each other can (and do!) become confused; in a segmented > machine done right, they can't; in most Intel machines, they can (and do!) > become confused (in the tiny, small, medium, and large models, for example). It can be done with either system, assumingthat you have an MMU that can handle it. In either case, you just have to assign a separate page to each item. This costs in page descriptors. However with the way that the intel '286 works, you're already paying that cost, in a lot of cases, so it's a lot more worthwile to take advantage of what's already been paid for. I think this is why the 'one segment per article' rule tends to be more available with the '286 (esp. once you go beyond the small memory model). -- ------------- Stephen Samuel {ihnp4,ubc-vision,vax135}!alberta!edm!steve or userzxcv@uqv-mts.bitnet