Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!zaphod.mps.ohio-state.edu!caen!ox.com!emory!gatech!mcnc!borg!hatteras!mccabe From: mccabe@hatteras.cs.unc.edu (Daniel McCabe) Newsgroups: comp.sys.mac.system Subject: Re: Virtual 32-bit clean ROMs Message-ID: <3371@borg.cs.unc.edu> Date: 22 Apr 91 18:51:18 GMT References: <3336@borg.cs.unc.edu> <1991Apr21.025813.5339@agate.berkeley.edu> Sender: news@cs.unc.edu Organization: University of North Carolina, Chapel Hill Lines: 46 In article <1991Apr21.025813.5339@agate.berkeley.edu> c186bx@volga.Berkeley.EDU.UUCP (Dan X. Filner) writes: >unless... if devices on the NuBus were using hooks to where the >ROMS were physically supposed to be then it wouldn't work too well. >But I don't think that's the case... Accessing fixed locations within the ROM is verboten, because the locations might change from ROM to ROM. However, the MMU would map those accesses into the virtual ROM anyway. >The terminology is a little misleading however - you wouldn't really be >"Virtualizing" the ROMS - you'd only be mapping some RAM to where the ROMS >really are... >You couldn't really make the ROM's "virtual" since the virtual memory >handler is probably going to rely on the code in the ROM's - >you can't page your pager out, that's fer sure... I didn't intend to have the ROM's page out (although permitting it to swap would reduce the loss of real RAM). I would bet that you want to lock your virtual ROM into memory. >Problems would seem to arise only in Legal form- if Apple were as >easygoing with it's ROM upgrades as with the System then we could all rest >happily... as I understand it Apple really, really, really doesn't like >the idea of letting ROM's be copied/publicly available. Letting every >mid-lifed Mac copy ROMS on a free-ware basis might sort of stick in >their throats. I hope not. I am not advocating that users copy new ROM images. I am proposing that Apple ship a 32-bit clean ROM image with System 7. (You might quibble about the legal implications of that action, but I don't want to get into it). >If anyone knows why this scheme wouldn't work, please let me(us all) know! >Dan Filner >c186bx@volga.berkeley.edu Enquiring minds want to know. Cheers, danm P.S. I should have posted this disclaimer with my original message, but I forgot. No deception was intended. Therefore, I mention it at this time. Disclaimer: I am employed by a competitor of Apple. However, I have invested my personal funds in Apple's products. I don't want to reduce the value of that investment by letting Apple make my equipment obsolete.