You might have more luck asking on a vintage Mac-specific forum, but is there any reason to think the memory controller on that thing can handle more than 32MB? Generally speaking, where Apple memory controllers support more than the 'advertised' maximum, that's quite well documented on places like everymac.

This was the era where Apple made it a point to limit their low-end systems' memory capability, e.g. the LC/LC II being limited to 10MB. The LC II even has 4 megs on board, but with 2x4 meg SIMMs it will only recognize 10 megs, just because Apple was being Apple. You have to situate this era in Apple history - you have peak Gasseeism in the late 1980s where they only launch new, higher-priced high-end machines (peaking with the IIfx in early 1990) while leaving the existing machines in the lineup at the existing prices, then they realize that it was a huge mistake not to have any reasonably-affordable colour Macs, so they launch the LC/IIsi in late 1990 (and slash the price of the 9" CRT/68000 model when they replace the Plus/SE with the Classic), but they make it a point to hobble those machines so that they don't threaten the sales of Gassee-priced machines like the IIci, Quadra 700, etc. And that strategy to some extent would continue until the return of Steve Jobs and the Great Simplification of the product line - look at the dreadful, dreadful reputation of the 6200 as an example.

Also, did any Apple 72-pin systems support more than 32 meg SIMMs? Even, say, high end machines like a Power Mac 8100 (and boy, maxing out 8 slots in one of those or in the other professional-grade Macs would have been really expensive), I don't think there's any indication that they supported more than 32 meg modules.

Keep in mind the times - I remember paying $250CAD for a 4 meg 72-pin SIMM for a Windows machine in spring 1995. Absolutely no one was going to put a 16 or 32-meg SIMM in a low-end system like a Performa 550 at the time. I don't want to know what a 32-meg SIMM would have cost in 1994-1995 - probably as much as the entire computer.

(It's funny, of course, because in 2023, you can max out any of those systems for... next to nothing. I don't see OWC selling 72-pin SIMMs, but they have 30-pin SIMMs for the older Macs, and 8 of those to max out a IIci-type machine with 128 megs would cost you $96USD for brand new RAM. 256 megs of PC100 for a beige G3 is $8.79, so you can max one of those with 768 megs for $26USD.)

I would add one other point - why are you interested in putting more RAM in this machine? If this is a project, like some of dosdude1's crazy projects soldering new CPUs to Apple logic boards, then I understand.

If this is a practical question, then 36 megs of RAM is more than you'll ever need for a 68K Mac. The classic Mac OS doesn't really have virtual memory in the way that, say, Windows or *NIX does. (Yes, it has optional virtual memory, at least on systems with MMUs, but no one with 36 megs of RAM on a 68K Mac would ever turn that on.) Applications get their own slices of memory that is fixed when you start them up. Unlike an OS with virtual memory where you are basically guaranteed a performance boost by adding more RAM (at least to a certain point), the classic Mac OS won't get faster by throwing more memory at it, though it will let you have more applications open. And unlike more modern OSes, the classic Mac OS doesn't use any unused RAM as a cache, I don't think...

VivienM wrote on 2023-08-19, 22:32:

You might have more luck asking on a vintage Mac-specific forum, but is there any reason to think the memory controller on that […]
Show full quote

You might have more luck asking on a vintage Mac-specific forum, but is there any reason to think the memory controller on that thing can handle more than 32MB? Generally speaking, where Apple memory controllers support more than the 'advertised' maximum, that's quite well documented on places like everymac.

This was the era where Apple made it a point to limit their low-end systems' memory capability, e.g. the LC/LC II being limited to 10MB. The LC II even has 4 megs on board, but with 2x4 meg SIMMs it will only recognize 10 megs, just because Apple was being Apple. You have to situate this era in Apple history - you have peak Gasseeism in the late 1980s where they only launch new, higher-priced high-end machines (peaking with the IIfx in early 1990) while leaving the existing machines in the lineup at the existing prices, then they realize that it was a huge mistake not to have any reasonably-affordable colour Macs, so they launch the LC/IIsi in late 1990 (and slash the price of the 9" CRT/68000 model when they replace the Plus/SE with the Classic), but they make it a point to hobble those machines so that they don't threaten the sales of Gassee-priced machines like the IIci, Quadra 700, etc. And that strategy to some extent would continue until the return of Steve Jobs and the Great Simplification of the product line - look at the dreadful, dreadful reputation of the 6200 as an example.

Also, did any Apple 72-pin systems support more than 32 meg SIMMs? Even, say, high end machines like a Power Mac 8100 (and boy, maxing out 8 slots in one of those or in the other professional-grade Macs would have been really expensive), I don't think there's any indication that they supported more than 32 meg modules.

Keep in mind the times - I remember paying $250CAD for a 4 meg 72-pin SIMM for a Windows machine in spring 1995. Absolutely no one was going to put a 16 or 32-meg SIMM in a low-end system like a Performa 550 at the time. I don't want to know what a 32-meg SIMM would have cost in 1994-1995 - probably as much as the entire computer.

(It's funny, of course, because in 2023, you can max out any of those systems for... next to nothing. I don't see OWC selling 72-pin SIMMs, but they have 30-pin SIMMs for the older Macs, and 8 of those to max out a IIci-type machine with 128 megs would cost you $96USD for brand new RAM. 256 megs of PC100 for a beige G3 is $8.79, so you can max one of those with 768 megs for $26USD.)

I am assuming that because it can address 36mb that it propbably can do 48 or 64mb. though the motherboard isn't wired for it. (yet) I intend to see if I can rewire it?

VivienM wrote on 2023-08-19, 23:00:

I would add one other point - why are you interested in putting more RAM in this machine? If this is a project, like some of dosdude1's crazy projects soldering new CPUs to Apple logic boards, then I understand.

If this is a practical question, then 36 megs of RAM is more than you'll ever need for a 68K Mac. The classic Mac OS doesn't really have virtual memory in the way that, say, Windows or *NIX does. (Yes, it has optional virtual memory, at least on systems with MMUs, but no one with 36 megs of RAM on a 68K Mac would ever turn that on.) Applications get their own slices of memory that is fixed when you start them up. Unlike an OS with virtual memory where you are basically guaranteed a performance boost by adding more RAM (at least to a certain point), the classic Mac OS won't get faster by throwing more memory at it, though it will let you have more applications open. And unlike more modern OSes, the classic Mac OS doesn't use any unused RAM as a cache, I don't think...

mostly just to see if I could. this was my childhood computer. in my teens I upgraded it to 36mb and wanted to do more but was unable

will also help with ram disk experiments

https://tinkerdifferent.com/threads/breaking- … the-lciii.1344/

Look what snufkin found!

Sphere478 wrote on 2023-08-22, 15:42:

https://tinkerdifferent.com/threads/breaking- … the-lciii.1344/

Look what snufkin found!

Wow... so... after 29 years, someone has been exploring that kind of craziness.

Nice ! Yeah Apple was a biatch back then, the Apple stores would charge 3x or more what it really cost to replace a HD or add memory. Kinda like the rip off from the gaming community now where you have these online "subscriptions" which can cost 100's for a game (over time) you used to buy for just $50 and play forever if wanted, just a few years ago...