johnr@runxtsa.runx.oz.au (John Rotenstein) (07/07/90)
System 7.0 requires a 32-bit clean ROM to operate virtual memory above 14MB. With such a ROM, it can go to 1 gigabyte. So, the question... Which Macs have a 32-bit clean ROM, and will Apple be supplying a ROM upgrade for those that don't? John Rotenstein UUCP: johnr@runxtsa.runx.oz PO Box 165 Double Bay, NSW 2028. AUSTRALIA. HappiWare to the World! ---------
alexr@ucscb.ucsc.edu (Alexander M. Rosenberg) (07/10/90)
In article <1935@runxtsa.runx.oz.au> johnr@runxtsa.runx.oz.au (John Rotenstein) writes: > System 7.0 requires a 32-bit clean ROM to operate virtual memory above 14MB. > With such a ROM, it can go to 1 gigabyte. Don't you mean 4 gigabytes? :-) --------------------------------------------------------------------------- - Alexander M. Rosenberg - INTERNET: alexr@ucscb.ucsc.edu - Yoyodyne - - 330 1/2 Waverley St. - UUCP:ucbvax!ucscc!ucscb!alexr - Propulsion - - Palo Alto, CA 94301 - BITNET:alexr%ucscb@ucscc.BITNET- Systems - - (415) 329-8463 - Nobody is my employer so - :-) - - - so nobody cares what I say. - -
esmith@apple.com (Eric Smith) (07/10/90)
In article <9048@goofy.Apple.COM> alexr@ucscb.ucsc.edu (Alexander M. Rosenberg) writes: > In article <1935@runxtsa.runx.oz.au> johnr@runxtsa.runx.oz.au (John > Rotenstein) writes: > > System 7.0 requires a 32-bit clean ROM to operate virtual memory above > 14MB. > > With such a ROM, it can go to 1 gigabyte. > > Don't you mean 4 gigabytes? :-) Well, he does and he doesn't. There is only 1 gigabyte of address space allocated contiguously from addresses $00000000 through $3FFFFFFF for RAM. It is possible to have RAM on NuBus cards from $60000000 through $EFFFFFFF (superslot space for slots $6 through $E) and from $F1000000 through $FEFFFFFF (slot space for slots $1 through $E). Note that not all of these slots exist on any given Mac, although to my knowledge nothing but courtesy prevents a card in one slot from responding to addresses reserved for another slot. The total slot and superslot space is therefore 2318 (decimal) megabytes, although some of the slot space is taken up by declaration ROMs. To use the slot memory for main RAM (as opposed to a RAM disk or something), it is necessary to either have an PMMU (either as part of the processor or separate), or make the Memory Manager understand non-contiguous memory. If you have a PMMU, you do not necessarily have to have virtual memory to remap the slot memory to be contiguous with main RAM. Virtual memory in System 7.0 does handle noncontiguous memory in 24-bit mode in order to allow memory beyond 8 megabytes to be mapped above the ROMs and IO. I don't know whether VM supports noncontiguous memory in 32-bit mode. ---- Eric Smith esmith@apple.com Opinions expressed herein are not necessarily those of my employer, family, friends, computer, or even me! :-)
chewy@apple.com (Paul Snively) (07/17/90)
In article <1935@runxtsa.runx.oz.au> johnr@runxtsa.runx.oz.au (John Rotenstein) writes: > System 7.0 requires a 32-bit clean ROM to operate virtual memory above 14MB. > With such a ROM, it can go to 1 gigabyte. > > So, the question... > > Which Macs have a 32-bit clean ROM This one's easy: the Macintosh IIci and the Macintosh IIfx. > and will Apple be supplying a ROM upgrade for those that don't? This one's not so easy. I'm afraid that I don't know. __________________________________________________________________________ Paul Snively Macintosh Developer Technical Support Apple Computer, Inc. chewy@apple.com Just because I work for Apple Computer, Inc. doesn't mean that I believe what they believe, or vice-versa. __________________________________________________________________________
ml10+@andrew.cmu.edu (Michael A. Libes) (07/19/90)
I've never seen it written, but I've heard that the IIfx ROMs are
backward compatible with the older Mac II models. Has anyone tried
dropping a IIfx ROM SIMM into a II or IIx?
- Lunarmobiscuit