Article View: comp.sys.mac
Article #26415Preemption vs. VM
From: Phil Goldman
Date: Wed, 16 Mar 1988 08:30
Date: Wed, 16 Mar 1988 08:30
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1459 bytes
In article <7681@agate.BERKELEY.EDU> mwm@eris.UUCP (Mike (My watch has windows) Meyer) writes: >[Followups have been pointed to comp.sys.68k.] > >In article <7670@apple.Apple.Com> goldman@apple.UUCP (Phil Goldman) writes: ><I think one point you are both missing out on is that preemptive multitasking ><requires hardware support not available on a 68000. > >Right. So how did Sun, Apollo, Amiga, Sage, Stride and a multitude of >others manage to market 68000 systems that did preemptive >multitasking? >... >Here is where the 68000 has problems: there's not enough information >around to restart a process that page faults in the middle of some >instructions. The 68010 & later processors fixed this. But people >found ways around that problem with thoe 68000. I stand (very) corrected. I was confusing doing VM on 68000 w/ preemption. In VM it is impossible to restart the instruction if it causes a page fault, but as far as a generic interrupts (i.e. not addr err and bus err) go this is definitely possible on the 68000. Please excuse my last (late night) posting. -Phil Goldman Apple Computer
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Path: arc1-ca.pugleaf.net!utzoo!mnetor!uunet!husc6!think!ames!claris!apple!goldman From: goldman@Apple.COM (Phil Goldman) Newsgroups: comp.sys.mac Subject: Preemption vs. VM Message-ID: <7705@apple.Apple.Com> Date: 16 Mar 88 08:30:44 GMT Reply-To: goldman@apple.UUCP (Phil Goldman) Organization: Apple Computer Inc, Cupertino, CA Lines: 24