Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: version B 2.10.2 9/3/84; site enmasse.UUCP Path: utzoo!watmath!clyde!bonnie!akgua!whuxlm!harpo!decvax!genrad!panda!enmasse!mroddy From: mroddy@enmasse.UUCP (Mark Roddy) Newsgroups: net.micro.atari Subject: Multitasking on the Amiga Message-ID: <450@enmasse.UUCP> Date: Mon, 19-Aug-85 09:39:33 EDT Article-I.D.: enmasse.450 Posted: Mon Aug 19 09:39:33 1985 Date-Received: Sat, 24-Aug-85 14:14:11 EDT References: <268@ihnet.UUCP> <1669@hao.UUCP> <5436@fortune.UUCP> <338@eneevax.UUCP> <2344@watcgl.UUCP> Distribution: net Organization: Enmasse Computer Corp., Acton, Mass. Lines: 30 > Not true. Programs can be arbitrarily large (since addresses are relocated > at process startup time) and they don't have to be well behaved > (since address faults, etc are trapped on a per-process basis). > Well I for one don't see how either of these assertions can be true. 1) Programs can't be arbitrarily large, they have to fit into what is left of memory, a variable dependent on what happens to be loaded at the time. This is not the same as a multiprocessing system that allows any combination of processes to coexist, limiting only the number of concurrent processes. 2) They do have to be well behaved. This is far more serious a problem with the base register relocation scheme used in the Amiga. There is no way to prevent task_1 from writing all over task_2. Without the hardware protection offered by an MMU, you are left with trust as the only protection between the address space of individual tasks. I must assume that the address faults mentioned above are writing off the end of known space type faults. > I got this information from one of the people who designed the Amiga's > multitasking operating system. All in all, I was very impressed > by the number of things that they got right. These people are not objective. -- Mark Roddy Net working, Just reading the news. (harvard!talcott!panda!enmasse!mroddy)