Xref: utzoo comp.sys.mac.hardware:4234 comp.sys.mac.misc:1063 Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!uunet!efi!tim From: tim@efi.com (Tim Maroney) Newsgroups: comp.sys.mac.hardware,comp.sys.mac.misc Subject: Re: Addressable memory of 68000 (was Re: New Macs) Message-ID: <1990Jul5.204534.14336@efi.com> Date: 5 Jul 90 20:45:34 GMT References: <90178.172523KPURCELL@LIVERPOOL.AC.UK> <268ACACA.44FD@intercon.com> <316@opusc.CS.SCAROLINA.EDU> <1990Jul4.003731.336@hellgate.utah.edu> <26708@netnews.upenn.edu> <42651@apple.Apple.COM> Organization: Electronics For Imaging, Inc. Lines: 16 jeff@eniac.seas.upenn.edu (Jeff White) writes: >>On a related note, does anyone know if the 68000 can address more than 4 Megs >>of RAM (ie. is the present 4 Meg limit with Pluses and SE's a 68000 limit or >>just the way Apple designed those systems)? In article <42651@apple.Apple.COM> austing@Apple.COM (Glenn L. Austin) writes: >The problem is that the ROMs on the Plus and SE are located at the 4MB >address location. Since the Memory Manager doesn't know how to handle >non-contiguous RAM, 4MB is the limit on these machines. Couldn't you do a software fix? At startup, tweak the MultiFinder pseudo-heap so that the ROM space is marked as allocated? This would fragment the MF heap, of course, but it seems as if it would allow the memory above the ROM to be used with only a small change in software. Naturally, no applications could straddle the gap, given the Memory manager limitations.