goldman@Apple.COM (Phil Goldman) (03/16/88)
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