Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!tut.cis.ohio-state.edu!bloom-beacon!apple!oliveb!amiga!cbmvax!daveh From: daveh@cbmvax.UUCP (Dave Haynie) Newsgroups: comp.sys.amiga Subject: Re: UNIX vs. Amiga speeds Message-ID: <6441@cbmvax.UUCP> Date: 29 Mar 89 18:34:17 GMT References: <6411@cbmvax.UUCP> Organization: Commodore Technology, West Chester, PA Lines: 30 in article <6411@cbmvax.UUCP>, andy@cbmvax.UUCP (Andy Finkel) says: > In article shadow@pawl.rpi.edu (Deven T. Corzine) writes: >>REAL low-level stuff done already, like interrupt handling [rather >>poorly done, I'm afraid -- GURUs are a pretty piss-poor way to handle >>a program messing up and causing an address error or something. if it > As I recall, the 68000 has a bit of trouble recovering from > an address error. (not enough state info saved). > This was fixed in the 68010. (wasn't there a 68000 computer > that used 2 68000s to get around this one ?) It's actually bus error that's the problem. An address error is a programming error of some kind, and that can be caught, and the program removed, given a sufficiently enthusiastic operating system. For virtual memory, though, you have external logic generate a bus error if you try to access memory that's swapped out. The problem is that the 68000 bus error doesn't save enough state to either retry or continue the instruction, so real VM just plain won't work on a single 68000. Our old Apollos used the 2 68000 trick to support virtual memory. All the currently used Apollos here are based on a bit-slice machine that emulates a 68010. Hopefully soon we'll have some that can keep up with our Amigas... > andy -- Dave Haynie "The 32 Bit Guy" Commodore-Amiga "The Crew That Never Rests" {uunet|pyramid|rutgers}!cbmvax!daveh PLINK: D-DAVE H BIX: hazy Amiga -- It's not just a job, it's an obsession