Path: utzoo!news-server.csri.toronto.edu!cs.utexas.edu!sun-barr!lll-winken!uunet!munnari.oz.au!comp.vuw.ac.nz!canterbury!otago.ac.nz!michael From: michael@otago.ac.nz Newsgroups: comp.sys.mac.hardware Subject: Re: LC video vs. SI video... Message-ID: <1991Mar6.094536.125@otago.ac.nz> Date: 5 Mar 91 21:51:37 GMT References: <1991Feb25.131316.1@gacvx1.gac.edu> <1991Feb26.134342.25399@magnus.ircc.ohio-state.edu> Organization: University of Otago, Dunedin, New Zealand Lines: 22 In article , ingemar@isy.liu.se (Ingemar Ragnemalm) writes: > This only occurs when the running program is located in the lowest meg, > thus sharing that meg with the video. A program running in a higher part > of the memory runs at full speed even in 8-bit mode. > This doesn't sound like the whole story. Surely the video image can't be sitting there in the middle of the heap (can it?). I understand Apple are using the MMU to remap things, so presumably what we have is whatever portion of the 1 meg is left over from the video (716K in 8-bit mode) mapped somewhere into the main space and whatever other RAM you have in the other bank mapped around it. Presumably the MMU has the flexibility to put this slow RAM anywhere, so it would be interesting to know exactly what Apple have done and why. I hope they have picked a spot based on careful analysis of average memory use... Michael(tm) Hamel, Computing Services Centre, University of Otago, New Zealand HASTINGS (pl. n.) Things said on the spur of the moment to explain to someone who comes into a room unexpectedly precisely what it is you are doing.