Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!sun-barr!olivea!spool.mu.edu!caen!zaphod.mps.ohio-state.edu!pacific.mps.ohio-state.edu!linac!att!ucbvax!FANDM.BITNET!NJ_GOKEMEIJE From: NJ_GOKEMEIJE@FANDM.BITNET Newsgroups: comp.sys.amiga.advocacy Subject: difference between 7.0 and amiga multitasking Message-ID: <330863744000293E@FANDM> Date: 17 Jun 91 18:52:00 GMT Sender: daemon@ucbvax.BERKELEY.EDU Lines: 59 From: BGBIRD::NJ_GOKEMEIJE 17-JUN-1991 13:41:42.82 To: INTR CC: NJ_GOKEMEIJE Subj: re:RE: difference between 7.0 and amiga multitasking In article Chris Gray. writes: >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 > In a way you are right, if the user wants to switch from one program to another, the mac is only seconds slower than the amiga. (because at activation time, all the windows are brought to front and are refreshed.) The big difference is that on a mac, the frontmost program gets all the time in wants, and has control over how much time it gives to other programs. This is not like the amiga, where the tasks priority determines the timesharing. If you use the computer primarily for dtp orso, where the computer usually runs idle for 80% if the time anyway, the two systems work very similar. But if you have the computer do a lot of work, like making a back-up, mathematical calculation, ray-tracing, mandelbrot series etc, it is really nice that you can give that program a low priority, so that you can do other stuff, like editing orso at the same time, without noticing that the computer is working as fast as it can. Printing is a good example. Background printing on a MAC is slower because it gets less time. forground printing makes you wait. Printing on an amiga is always as fast a possible, except if the user wants the cpu for a program with higher priority. THere is no diffence between a main program and background programs. Hopes it helps. Nils Gokemeijer (NJ_GOKEMEIJE@FANDM.bitnet)