mkelly@geriatrix.cs.uoregon.edu (Michael A. Kelly) (04/13/91)
In article <1991Apr11.165406.6175@cs.uoregon.edu> mkelly@obelix.cs.uoregon.edu (Michael A. Kelly) writes: > >I've heard that the IIcx can only access about 13-14 Meg of RAM with the >virtual memory feature of System 7. Is this true for RAM in general? >E.g., if I go out and buy four 4-meg simms and plug them into my IIcx, and >leave four 1-meg simms in the other bank, will I have 20 meg of RAM at my >disposal? > Thanks to all who replied to my question. This reply (from Dave Platt) sums them all up: That's correct; yes; and no... in that order. The IIcx ROMs are not "32-bit clean." This means that the machine can run only in 24-bit mode... 24 bits of address space give you a 16-megabyte address range. One meg is consumed by the ROM, and one meg is consumed by each NuBus card... typically leaving you 14 megs of address space that can be mapped into RAM. If you install 4 4-meg SIMMs, you might as well pull the old 1-meg SIMMs out and use them in another machine. Until Apple decides to upgrade the IIcx ROMs (if they ever do), you won't be able to use more than 16 megs of address space, either direct or VM-paged, regardless of the amount of RAM you have installed. It's possible that you might be able to use a third-party utility to access the above-the-waterline memory as a RAMdisk... Connectix in Menlo Park, CA may have something along this line. -- Dave Platt VOICE: (415) 813-8917 UUCP: ...apple!ntg!dplatt USNAIL: New Technologies Group Inc. 2468 Embarcardero Way, Palo Alto CA 94303 So, if I buy four 4-meg simms and put them in my IIcx, and then later upgrade to a IIfx (or later), could I use those 4-meg simms in the new machine? I hear the IIfx requires special memory chips - do they work in other machines? Thanks, Mike. -- _____________________________________________________________________________ Michael A. Kelly America Online: Michael792 mkelly@cs.uoregon.edu Compu$erve: 73567,1651 _____________________________________________________________________________
hp48sx@wuarchive.wustl.edu (HP48SX Archive Maintainer) (04/13/91)
Can I take an old IIci ROM and put in my SE/30 to get 32-bit clean ROMS? Or are there any machine specific dependencies in the ROM ? I work for an Apple Dealer, and has access to broken boards before they are returned. We also have a machine where I work (a IIcx) who can not be turned off in the shutdown menu. You have to disconnect power. It seems that it believes that it is an SE orSE/30. So it seems somebody tried this before. Please respond by mail. -- ******************************************************* Povl H. Pedersen hp48sx@wuarchive.wustl.edu HP48sx archive maintainer
awessels@ccwf.cc.utexas.edu (Allen Wessels) (04/14/91)
In article <1991Apr13.094919.9148@wuarchive.wustl.edu> hp48sx@wuarchive.wustl.edu (HP48SX Archive Maintainer) writes: >Can I take an old IIci ROM and put in my SE/30 to get 32-bit clean ROMS? >Or are there any machine specific dependencies in the ROM ? I work for >an Apple Dealer, and has access to broken boards before they are >returned. In a post on CompuServe, an ex-Apple employee said that the only ROM you could do this with is the fx ROM, if it is doable at all. According to that post, the fx ROM checks the hardware to see if a given feature is available. If someone with access could check this out and post the results, it would be a great service to a LOT of people. At least they would know it is technically possible to get a 32-bit clean ROM upgrade.