Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!zaphod.mps.ohio-state.edu!mips!atha!aunro!alberta!ami-cg!cg From: cg@ami-cg.UUCP (Chris Gray) Newsgroups: comp.sys.amiga.introduction Subject: Re: Difference between 7.0 and AMIGA multitasking???? Message-ID: Date: 15 Jun 91 21:13:07 GMT References: <1991Jun13.190302.16896@ccu.umanitoba.ca> <1991Jun14.154041.15151@world.std.com> Organization: Not an Organization Lines: 28 In article <1991Jun14.154041.15151@world.std.com> awm@world.std.com writes: [stuff about register save/restore deleted] >> I think he might be mixing memory with registers. > >This seems likely. Unless you have virtual memory, you can only run as many >applications as will fit in main memory. However, most machines these days >have enough space for a large number of applications to run at once, and >the speed at which you can switch between them definitely depends on the >operating system. Another significant factor is how much of the operating system state needs to be saved/restored on a task switch. Since the Amiga's Exec was designed with task switching in mind, this is a relatively simple affair (not much more than moving a couple of pointers). I recall reading an old article in Byte, however, that said that one of the problems that MultiFinder has is that the Mac's OS has a LOT of state that has to be manually preserved when switching tasks. Basically, anything that is task-specific and at a fixed location must be entirely copied out and saved, then the stuff for the new task copied back in. Mac guru's could likely expand on this. It really doesn't have too much effect, however, unless you try to switch tasks too often. If the switching is at a human speed, you won't likely notice it on a 68020 or higher. At 100 times a second, you might. -- Chris Gray alberta!ami-cg!cg or cg%ami-cg@CS.UAlberta.CA