Thread
LC 575 Memory Limit
According to most docs the LC575 maximum RAM is 36MB, though I've found a few mentions of 68MB being possible... I wonder if anyone's done this (or more?) and how it turned out. Any stability issues?
The LC575 is basically a 475 with a faster CPU and a built in display. I've heard of people taking LC475s all the way up to 132MB before, so I can't see why you wouldn't be able to do it with the 575.
Chris Lawson's research is reported at:
http://macfaq.org/hardware/memory.shtml
Locating a suitable SIMM today may be more difficult, so be prepared to buy a few and make sure that you have a generic PC or whatever in which to install the majority that don't work. SIMMs identified as working in a PowerMac 6100 or Acorn RISC are a decent bet.
http://macfaq.org/hardware/memory.shtml
Locating a suitable SIMM today may be more difficult, so be prepared to buy a few and make sure that you have a generic PC or whatever in which to install the majority that don't work. SIMMs identified as working in a PowerMac 6100 or Acorn RISC are a decent bet.
I've had at least two LC575 boards that ran fine with 128MB SIMMs installed. True, they need to be the right kind (single-banked - which has nothing to do with whether the SIMM is one or two sided or not) - but with the right kind, the machine runs great.
Just bought a new keyboard for my peecee, so I figured I'd break it in a bit. I LUUUURVE scissor keys.
AFAIK, the Mac TV was the only Mac where the Apple-specified limit was actually adhered to; virtually every other machine could accept waaaay more than Apple claimed. I've got a small cache of 64 and 128MB 72-pin SIMMs, and in all the machines I've tried them, from LC IIIs to 8100s, they've all been recognized fully. A 6100 with 264MB of RAM (128x2 + 8MB soldered)is a trip. So is a Quadra 840AV with 512MB (128x4).
The PowerBook 2400c is quoted by Apple as having a max of 80MB (64MB SODIMM + 16MB soldered), though a Japanese company made a 96MB SODIMM that brought its max beyond that limit to 112MB.
Really, the limits are set when engineers test the maximum of readily available RAM modules, and you know how technology can progress.
Then, of course, there's the Mac TV. It completely refuses to use more than 8MB of RAM. Something about the weird circuitry they used to accommodate the TV system, I dunno. But it sucks, and a stripped System 7.5.5 with ClarisWorks 4.0, maybe with Oregon Trail or SimCity 2000 for games, is all I care to run on that thing.
AFAIK, the Mac TV was the only Mac where the Apple-specified limit was actually adhered to; virtually every other machine could accept waaaay more than Apple claimed. I've got a small cache of 64 and 128MB 72-pin SIMMs, and in all the machines I've tried them, from LC IIIs to 8100s, they've all been recognized fully. A 6100 with 264MB of RAM (128x2 + 8MB soldered)is a trip. So is a Quadra 840AV with 512MB (128x4).
The PowerBook 2400c is quoted by Apple as having a max of 80MB (64MB SODIMM + 16MB soldered), though a Japanese company made a 96MB SODIMM that brought its max beyond that limit to 112MB.
Really, the limits are set when engineers test the maximum of readily available RAM modules, and you know how technology can progress.
Then, of course, there's the Mac TV. It completely refuses to use more than 8MB of RAM. Something about the weird circuitry they used to accommodate the TV system, I dunno. But it sucks, and a stripped System 7.5.5 with ClarisWorks 4.0, maybe with Oregon Trail or SimCity 2000 for games, is all I care to run on that thing.
My LC575 has 68MB installed with 7.5.1 and stock components, I have never run into any stability issues at all - also then upgraded the CPU to a full '030 33Mhz, still runs great even at longer stretches.
A nice possibility you have with plenty of RAM is to use a RAM disk to contain system and application software and to run the beast with virtual memory off, or to use a RAM disk as a scratch disk (for number crunching, graphics manipulation or a software RIP). Top performance!
Btw: please be so kind and share your experience with the rest of us, improving the 68kMLA Wiki -> RAM module test results. This might save some money one needs not spend for known not working combinations.
Btw: please be so kind and share your experience with the rest of us, improving the 68kMLA Wiki -> RAM module test results. This might save some money one needs not spend for known not working combinations.
At the time the LC575 was released the maximum memory size per SIMM was at 32MB's Today you can purchase SIMM's of 128mb's
I read about Mystic CCs (= LC 575) pushed to the limit with use of a 128 MB memory module. I verified the nice operation of such module in a LC 475, no issues besides the extraordinary long duration for the memory count step in the boot process. In case you want to purchase a 128 MB PS/2 RAM module, be aware of the fact that not only different elctrical specified modules are available, but also different physical dimensions. Some modules will not fit into most machines without changing the angle of the slot or cutting out in the case. A module specified for a Performa 630 might be electrical compatible to a LC 475, but might interfere with the CPU chip or a heatsink.
Just posted this on the Trading Post forum, but thought I'd include it here, too:
I found a pretty good deal on eBay for 128MB SIMMs that I have confirmed are compatible (and small enough to fit properly) in the LC 475 / Quadra 605.
Samsung 128MB 32x36-60ns ECC SIMM KMM53632000AK-6U
$13.50 each with free shipping
http://cgi.ebay.com/Samsung-128MB-32x36-60ns-ECC-SIMM-KMM53632000AK-6U_W0QQitemZ110331791958QQ
My guess is these would also work fine with the LC 575
The auction indicates the seller has more than 10 available.
I found a pretty good deal on eBay for 128MB SIMMs that I have confirmed are compatible (and small enough to fit properly) in the LC 475 / Quadra 605.
Samsung 128MB 32x36-60ns ECC SIMM KMM53632000AK-6U
$13.50 each with free shipping
http://cgi.ebay.com/Samsung-128MB-32x36-60ns-ECC-SIMM-KMM53632000AK-6U_W0QQitemZ110331791958QQ
My guess is these would also work fine with the LC 575
The auction indicates the seller has more than 10 available.
Um, I'm really looking for a 128mb module for my Mystic CC so I was about to jump on this but then I realized that this is 60ns. Many sites (including low end mac: http://www.lowendmac.com/500/performa-575.html) list the machine as using 80ns RAM. Is the 80ns a minimum or maximum? How much would you expect speed to deteriorate using 60ns?
60ns RAM is faster than 80ns RAM, so I can't imagine there being a problem, it would likely just go back to 80ns, in the same way as if you use PC133 in a PC100 system (like a G3/G4), it just clocks back to the slower speed.
This module seems to be of "parity" type. Could someone please confirm it does work and fit properly inside a LC 475? Uptil now I was not lucky with parity EDOs in my LCs. Also this module is not what I would call a low profile module. It might interfere with the case of a CC (even with proper clearance inside the case a problem might occur when you try to slide in the mainboard.
The 6100 shipped with a 256MB hard drive 8-o
It would no doubt make video capture a breeze, if you
This module does fit properly and works perfectly inside a LC 475 (see the rest of my previous post here). I can't speak to the possible clearance issues in the Color Classic, however.
I was pretty excited until I saw the $27 international shipping fee 
Very nice: "strong buy!"
The 128mb stick referenced above works correctly and fits in my Color Classic on the LC575 motherboard with 33mhz 68LC040!
Really? I've tried 128 meg SIMMs in various Quadras, but I had no idea that the Q840AV actually works with 128 meg SIMMs... Nice!
Is this a machine you have / use?
90% of my stuff is in storage because of weight limits during moves, but yeah, the 840AV is one part of my collection. I fitted it with the RAM and a 7200RPM hard drive (the original was a 1st gen 5400RPM Seagate Hawk) and it's screaming fast.
And yeah, my first 6100/60 had a 250MB hard drive, so it's funny to have more RAM than I used to have disk space.
And yeah, my first 6100/60 had a 250MB hard drive, so it's funny to have more RAM than I used to have disk space.
The Q840AV does not work with 64MB nor 128MB SIMMs in my tests. It is possible that Franklinstein had some very differently organized SIMM, but that seems farfetched.
My experiments indicated that the Q840AV and the 7100 and 8100 do not recognize column, nor row addresses above 11 wires. So 11 + 11 bits is 22 bits or 4M addresses. A 72 pin SIMM is 4bytes wide, so one gets 16MB or addressable memory per bank in those machines and dual bank SIMMs can be 32 MB.
In my tests, 64 MB SIMMs are seen as 16MB and 128MB are seen as 32 MB in the above mentioned machines.
Now the 6100 will address 12 X 12 memory chips and it uses the same memory controller as the 7100 and 8100, so one might doubt my results. I was puzzled by this, so I traced the upper address line and the RAS lines back from the SIMM sockets in these machine. In the 6100 those lines go directly back to the memory controller (well, through buffers). In the 7100 and 8100 the upper address line and the RAS signals all pass through a CPLD before going to the memory sockets. My guess is that Apple did not build the memory controller with enough RAS lines to control multiple SIMM sockets. So they translate the RAS lines and upper addresses into multiple RAS lines in the CPLD and use that to support multiple SIMM socket banks.
The Q840AV appears to use the same addressing scheme as the x100 family, which is not surprising because they were so close to each other in development.
My LC 575 currently has 132MBs installed. I know that this particular memory module works with the LC 575.
Which means the total memory limit for all three x100 models are the same, right?
Edit: unfortuately not, because the fact that the 7100 have four SIMM sockets means that some RAS lines are wasted, cutting max RAM by half.
Now what about the 6200/6300/5200/5300 Power Macs? If these have the same memory controller as the Quadra 630, these should support up to 256 MB of RAM, right?
As long as it's not a Power Mystic, otherwise you're back to the 36MB RAM restriction. Apple giveth and Apple taketh away.
I can happily report that my Mystic CC has been running 132 mb very happily since I dropped the 128mb stick in a few months ago. That's 128mb stick + 4mb onboard. Actually, since I'm not really taking advantage of the memory, i've considered taking it out because of the ridiculous start-up time to count the memory. The unit powers on, makes its sound, and then the screen shows no sign of life for a very long time while counting, then boots to more memory than I need. I am thinking of trying to put seinfeld episodes into RAM disk, but otherwise I don't understand why I sought so much memory...other than that 4mb sucked.
Actually, might be 136mb (8mb internal) on second thought. I'll check when reunited with the troops.
Actually, might be 136mb (8mb internal) on second thought. I'll check when reunited with the troops.
You can turn that off
Glorious! How? I'm in System 7.1
I believe this to be restricted to 8.5 or possibly 8.6 and above. Anyway, it's a late system feature. You open the Memory Control Panel while holding down the Option or Control key or some such, and there is the extra option of turning off the startup memory test.