Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!usc!apple!agate!stanford.edu!neon.Stanford.EDU!news From: philip@pescadero.stanford.edu (Philip Machanick) Newsgroups: comp.sys.mac.system Subject: Re: Changes for preemptive multitasking Message-ID: <1991May11.182459.29470@neon.Stanford.EDU> Date: 11 May 91 18:24:59 GMT References: <811@newave.UUCP> <15931@helios.TAMU.EDU> <1443@cash.cs.utexas.edu> Sender: news@neon.Stanford.EDU (USENET News System) Organization: Computer Science Department, Stanford University Lines: 30 In article <1443@cash.cs.utexas.edu> mpretzel@cs.utexas.edu (Benjamin Allums) writes: > recompiled, but Apple will not release a multi-tasking OS until the > Mac memory model has been altered. Currently, applications assume that > they have complete access to all available memory. MultiFinder works > by allowing the user to specify the amount of memory that the program > may take. Under the Amiga, an application may request and release > additional memory on the fly, so memory use is more efficient. > > The reason why MultiFinder requires so much memory is this fact. The > current memory model blows tons of megs. If people start running all > kinds of little programs, probably 25% of main memory will be wasted. The MultiFinder model has alway allowed applications to request extra memory outside their initial space. Maybe this feature hasn't been much used up to now because MultiFinder isn't always on (of course this will change with SYstem 7). The real problem is fragmentation, which occurs because all applications are running in the same address space. Your proposal of what Apple should do (deleted) does not address this problem at all. I think the only way out of this is to design a completely new OS with a Mac compatibility mode, much the way AUX works (except I don't think this new OS should be unix). Your old Mac applications will still be able to run, but new applications will run directly under the new OS. >What I'm suggesting is the creation of a hybrid environment which allows pro- >grammers the ability to write applications for System 8 today and have them >run on System 7. And if they choose not to do so, then they do not. Since >all the work will have to be done some day, why not start working now on >smoothing the transistion to System 8? Now this I can agree with. Phliip Machanick