mjkobb@media-lab.media.mit.edu.MEDIA.MIT.EDU (Michael J Kobb) (04/24/91)
Greetings, Let's imagine that I suddenly have enough money to upgrade my IIx to a IIfx (ha!). So now, I need to buy memory. If I buy four 4-Meg SIMMS, and 4 1-meg SIMMS, I now have 20Mb of physical RAM. Okay, fine. In order to address that much memory, I need 32-bit addressing turned on (in System 7). My question is, how much memory will I see if I turn 32-bit off? (i.e. if I need to run some non-32-bit-happy software) I'm pretty sure this has been answered before, but I can't seem to find it anywhere. Email is fine, and I'll summarize. Thanks! --Mike
lemke@radius.com (Steve Lemke) (04/26/91)
mjkobb@media-lab.media.mit.edu.MEDIA.MIT.EDU (Michael J Kobb) writes: > Let's imagine that I suddenly have enough money to upgrade my IIx to a IIfx >(ha!). So now, I need to buy memory. If I buy four 4-Meg SIMMS, and 4 1-meg >SIMMS, I now have 20Mb of physical RAM. Let's imagine that instead, you purchased a Radius Rocket 68040 accelerator board to stick into one of your IIx NuBus slots (HA!). Now, let's assume that you _already_ have 8mb of memory on your IIx motherboard. You simply move that memory to the Rocket board, and find some old 256K simms (four, to be exact) to stuff into your motherboard - enough for your Mac to start up and switch over to the Rocket. Well, you just start up your system and presto, you're running faster than you would've been with the IIfx upgrade, and you have money left over too!! > Okay, fine. In order to address that much memory, I need 32-bit addressing >turned on (in System 7). My question is, how much memory will I see if I turn >32-bit off? (i.e. if I need to run some non-32-bit-happy software) If you turn 32-bit off on a IIci, IIfx or IIsi, the most you'll see is 8mb of real (physical) RAM. You can go up to 13mb, however, if you enable virtual memory. Of course, if you want to use big simms, you can go all the way to 128mb of RAM on the Rocket board (using 16mb simms)... This imaginary scenario provided as a courtesy to those who might be considering IIfx upgrades but are afraid that the IIfx might be too slow. :-) --Steve -- ----- Steve Lemke, KC6QDT - Software Engineering, Radius Inc., San Jose ----- ----- Reply to: lemke@radius.com -- U.C. Santa Barbara ECE Class of '89 ----- ----- "I'm not a UNIX wizard, but I play the Postmaster at radius.com." -----
mjkobb@media-lab.media.mit.edu.MEDIA.MIT.EDU (Michael J Kobb) (04/26/91)
Greetings, The responses I've received all indicate that without 32-bit addressing on, the Mac can only use 8 of the installed Megs of memory as RAM. The rest can be utilized, however, if you use ramdisk software. Also, you can run virtual memory, which can give you up to 13Mb of apparent RAM (depending on the number of cards you have installed. Thanks for the responses! --Mike