Tag Archives: RAM

Electronics and Computers, Macintosh, Posts

How Much Memory Does My Vintage Mac Really Accept?

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How Much Memory Does My Vintage Mac Really Accept?

In the early days of Macs, Apple stated the theoretical maximum memory a Mac could use. But with the Macintosh II, a mixture of issues meant that in reality, you really struggled to reach the theoretical 128MB. There were ROM bugs, you needed a Memory Management Unit upgrade, there was no 32bit addressing and the standards for RAM changed meaning the Mac II and IIx accidentally trigger a test mode in normal 4MB SIMMs and crash.

They got sued.

As a result, there after, Apple generally only quoted the maximum RAM a computer had been tested with during development, which was usually, but not always less than the actual maximum.

Note that maxing out the RAM on a Mac will make the built in RAM test take as long as 2 minutes in some cases. During the test the computer will sit with a black, empty screen. On later OSes, possibly from about Mac OS 8.5 onwards, it is possible to disable the Memory test with a hidden option in the Memory control panel. If I remember correctly, it appears when you open the control panel with the Command and Option keys held down.

For Apple’s official recommended maximum RAM for each machine, please see the Service Source document “Apple Memory Guide” from 1998. Where I haven’t included a machine on this page, either Apple’s maximum actually applied, or I’m unfamiliar with the model. Apples maximums apply to machines including the… Plus, SE, Classic, Classic II, Colour Classic, LC, LC II, LC III, IIvx, IIvi, IIci, IIfx, Quadra 660av, Quadra 840av, Quadra 900, Quadra 950, Performa 6200, Performa 6300, Performa 6400, Performa 6500, as well as other machines that are very similar (such as the 5*** series equivalents to 6*** machines, and Performa equivalents to LCs).

I’m not very familiar with PowerBooks, so have mostly excluded them.

Actual Capacities and Observations

The following does not consider hacks or modifications to ROM or hardware, but only what can be easily done by any user.

Macintosh II / IIx

128MB, but you’ll need IIx ROMs and a MMU in the Mac II, plus both need PAL SIMMs and either a 32bit clean ROM, or MODE32.

See Apple Memory Guide for how to correctly fill the two banks of RAM.

Macintosh IIcx & SE/30

128MB, but your’ll need a 32bit clean ROM or MODE32.

See Apple Memory Guide for how to correctly fill the two banks of RAM.

Macintosh IIsi

The IIsi will take four 16MB SIMMs plus the 1MB soldered, for a total of 65MB. Set your hard disk cache to 1MB for improved CPU performance due to a quirk of the video circuit design.

Performa / LC / Quadra 630 & LC / Performa 580

There are two logic board variants. A one RAM slot machine will take up to 128MB plus the onboard 4MB for a total of 132MB. A two slot machine will take up to 196MB. Note the second slot only works with 4, 16, or 64MB SIMMs.

The LC / Performa 580 uses the same board as the two slot 630.

LC / Performa 475, LC / Performa 575 / 577 & Quadra 605

These machines will accept a 128MB SIMM, for a total of 132MB including 4MB onboard.

Centris / Quadra 610

A quirk of the ROM in these machines means that even though the hardware is capable of seeing banks of up to 64MB, the ROM only checks for 32MB banks at most. There are up to two banks per SIMM, but not all SIMMs have two banks. Weirdly, this means that the most RAM you can fit is 128MB + onboard RAM (4MB) for 132MB total, but because 64MB SIMMs are usually single bank, you need to fit two 128MB SIMMs. The computer recognises each 128MB as two 32MB banks instead of two 64MB banks, but otherwise works fine.

Quadra 700

The Quadra 700 accepts up to four 16MB SIMMs plus 4MB of soldered RAM, for a total of 68MB.

Upgrade with a matched set of four.

Quadra / Centris 650 and Quadra 800

A quirk of the ROM in these machines means that even though the hardware is capable of seeing banks of up to 64MB, the ROM only checks for 32MB banks at most. There are up to two banks per SIMM, but not all SIMMs have two banks. Weirdly, this means that the most RAM you can fit is 256MB + onboard RAM (4 or 8MB) for a total of 260 or 264MB, but because 64MB SIMMs are usually single bank, you need to fit four 128MB SIMMs. The computer recognises each 128MB as two 32MB banks instead of two 64MB banks, but otherwise works fine.

Upgrade in matched pairs for improved performance due to memory interleaving.

Power Macintosh 4400

You can fit two 64MB SIMMs and one 32MB DIMMs for a maximum of 160MB. Thanks to D Cook for confirming this for me!

Warning : This machine requires 3.3V 168 pin DIMMs. Very unusual for this era of Macs.

Power Macintosh 6100

The Power Macintosh 6100 can actually recognise two 128MB SIMMs, plus 8MB onboard for a total of 264MB of RAM.

Upgrade with matched pairs.

Power Macintosh 7200 / 8200

Technically, the 7200 could recognise 768MB if you could find some 5V, FPM, 256MB SIMMs, short enough to fit in the chassis. I’ve never seen any. That means you’re likely looking at 384MB, which will be expensive as 168 pin 128MB 5V FPM DIMMs are not cheap.

Power Macintosh 7500, 7600, 7300, 8500 and 8600

Technically, if you could find 256MB 5V FPM or EDO DIMMs that fit the chassis, the maximum would be 1.5GB of RAM (limited by the OS). I’ve never seen any that aren’t too tall. That means you’re likely looking at 1GB, which will be expensive as 168 pin 128MB 5V FPM or EDO DIMMs are not cheap.

Can be upgraded individually, but works better with matched pairs.

Power Macintosh 9500 & 9600

With 12 slots, these will take up to 1.5GB using 128MB 168 pin, 5V FPM or EDO DIMMs.

Can be upgraded individually, but works better with matched pairs.

Power Macintosh G3 (Beige)

These machines will accept three 256MB PC66, PC100 or PC133 DIMMs for a total of 768MB. The DIMMs need to be physically short to fit in the desktop case, and additionally, “high density” DIMMs do not work. Practically, this means you need physically short DIMMs with 16 chips (eight on each side).

PowerBook G3 Pismo

Some (but not all) 512MB PC100 and PC133 SODIMMs work in the Pismo, for a maximum of 1GB of RAM.

Electronics and Computers, Mac OS 8, Mac OS 9, Macintosh, Posts, System 6, System 7

Classic Mac OS Memory Maximising Tricks

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Classic Mac OS Memory Maximising Tricks

When retro Macintosh computers such as the IIci, Performa 475 and even early (beige era) Power Macintoshes were current, RAM was extremely expensive. As a kid trying to push the capabilities of what I had, I sometimes would be in a situation where I just didn’t quite have enough RAM to run a program, for example because the software requires a specific, newer, version of the OS (with a larger footprint).

Today, RAM for these machines is effectively cheaper, but still expensive for some types, hard to find for others (such as the IIx) and lastly, some computers such as the SE or LC have fairly low hard limits.

Choose Your OS Carefully

The most obvious solution is to use an older OS as the further back you go, the less memory the Finder and System tend to use. System 7.1 tends to use around 1 to 1.5MB, while if you’re able to run System 6, requirements plumit into the low hundreds of kilobytes especially if you avoid using the MultiFinder.

If you’re short of memory on a PowerPC, try running a version of Mac OS 7 – the only beige PowerPC that won’t run Mac OS 7 in some form that I know of is the Beige G3. Some machines will even run slightly older versions than the official documentation suggests – for example the 9600 will boot 7.5.3. Note you might need a “System Enabler” for some combinations of computer and OS. These can be found on Macintosh Garden.

Setting up multiple disk partitions or disks, with older and newer supported systems, can be a great way of switching between more feature rich / compatible systems that consume more resources, and smaller, older, more lightweight systems to maximise available RAM.

Optimise

Sometimes you can gain some memory by uninstalling certain software installed in the System Folder. You might consider removing your screensaver, for example.

Suggested things to remove…

  • Always remove QuickDraw GX – it isn’t needed and uses a lot of RAM.
  • AfterDark or other ScreenSavers.
  • Printer Drivers you don’t need (and desktop printing).
  • Modem drivers.

Ensuring the hard disk cache size is sensible – if you’re short of memory on a sub 10MB machine, ensure the hard disk cache in the Memory Control Panel is set to 128k or 96k.

If you are using a Power Macintosh, you will often find that enabling 1MB of Virtual Memory in the Memory Control Panel will actually free significant amounts of RAM, especially in Mac OS 8.* and 9.*. Some software refuses to run if Virtual Memory is enabled, other software won’t run without it. Generally, avoid using greater amounts of Virtual Memory – if you really need more RAM, buy more RAM. Real RAM is many times faster than Virtual Memory.

So You Have a II or IIx, or Perhaps a IIfx?

Getting RAM for these machines can be a nightmare, because they need special RAM. “PAL” RAM in the case of the II and IIx (plus complications with respect to ROM versions and memory controllers on the II), and unique form factor RAM for the IIfx.

This is the one and only situation where I would recommend using virtual memory (perhaps also the LC II, Classic II and ColourClassic), but I would specifically recommend the software “RAMDoubler”. Ignore the jeering PC enthusiasts who dismiss this sort of software as snake oil – their platform has a history of scams in this area. The RAMDoubler product is an impressive piece of engineering that attempts to Ballance available RAM, CPU and hard disk. Default settings will give you 100% extra RAM, by compressing the contents of a portion of your RAM. This increases your CPU load, but means the most likely to be reused parts of memory are normal speed while the remaining is still faster than hard disk based virtual RAM. I’m writing from memory, but I believe that the software also performs more agressive memory tidying and may move less frequently used items to disk… But I suggest reading the manual.

At Boot-Time

Another simple solution would could be to boot with shift held down to disable Extensions, but this wouldn’t always work if your program or game required certain extensions to function. Starting up with Extensions disabled reduces the RAM your OS uses to the minimum.

When your software mandates some extensions, you can create and save a minimum extension set using the Extensions Manager. This can be easily accessed by holding space during boot on System 7.5 and later (when it is installed), but it can also be added to earlier versions of System 7, and older versions exists even for System 6.

Extensions Manager allows you to add and remove Extensions and Control Panels and then save “sets”. You can create several, for each of your favourite RAM hungry applications or games. It is also useful for troubleshooting crashes during boot, as it loads early (before most Extensions), loads the interface by holding spacebar, and allows you to remove everything to confirm the OS boots with a minimum config (otherwise the issue is likely the core OS, hard disk or other hardware) add then things back few at a time until you identify what is causing the issue.

Who Needs the Finder Anyway?

The last trick I used to use as a child was to write AppleScripts to quit the Finder and then launch the Application you want. This only works in marginal cases, but has got me out of a hole a few times, including when an Installer application would not launch any other way on a particular machine. Only minimal AppleScript support is required because all applications understand the “open” apple event, but best AppleScript compatibility is with Finder 7.1.2 (so a copy of System 7.1 with Finder 7.1.3 or 7.1.4 installed is a good configuration) or later as this will enable you to do more extensive scripts if you want. A basic script might be as follows :

tell application “Finder”
quit
end tell

tell application “MemoryHog Pro 3.0”
activate
end tell

Save the script as an Application.

To produce a more extensive “Launcher” type AppleScript, you might consider using FaceSpan, which allows you to produce AppleScript based Applets with fancy GUIs using a nice IDE.

Summary

Hope this page is useful to someone. I remember having difficulty getting Escape Velocity to run due to memory restrictions, as well as trying to maximise RAM available for Director 4 (to increase the available Cast size) and for recording sound to RAM.

If anyone has suggestions for what Extensions and Control Panels are memory hogs, or for any other memory saving tips, send me a message via my contact form (under the About drop-down).

General, Linux, Posts

Upgrading ReadyNAS Duo (v1) RAM

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A few years ago I bought myself a ReadyNAS Duo. I really like the thing – it has a steel case, rubber feet, three USB ports for external hard drives and printers and a gigabit ethernet port. I liked it so much I also bought my father one. Early on, I modified mine to allow root SSH access and it was actually the machine I learnt a lot of my Linux skills on. SSH can be enabled using the add-on listed here on the official Netgear site.

A few years later, I spotted an article on the internet which discussed upgrading the RAM in a ReadyNAS Duo, as the machine has a laptop style SODIMM slot. As the RAM was now effectively “old”, second hand prices on eBay were extremely tempting, and so I decided to upgrade the original 256MB of RAM. Given that there were hardly any price differences between 512MB and 1024MB, I decided to go for the full Gigabyte of RAM. The part arrived and I installed it, it was recognised and everything was good. Interestingly, a while later I read more and discovered that lots of people have trouble performing this upgrade and many products with the correctly specification simply do not work or are unreliable. Seems I was lucky.

Fast forward further few years and I mentioned the RAM upgrade to my dad and we agreed that it would be interesting to upgrade his as well. I did some digging and re-discovered the issues people had. I decided to give it another go and ordered a couple of SIMMs from Hong Kong, where the second prices were lower for two than they were for one in the UK. The parts actually arrived in 7 days, which was better than I was expecting. Before giving a SIMM to my dad, I’ve decided to test it in my own ReadyNAS. Should you want to do something similar, the following should help.

Why More RAM?

There isn’t a huge benefit to upgrading the RAM in your ReadyNAS Duo. There may be small speed increases, but the main reasons I’ve done so are :

  1. It will allow me to run more other Linux software in the background, as long as it isn’t excessively processor intensive.
  2. It is not very expensive, with the upgrade costing approximately £3.50.
  3. Because I can, and that is often reason enough.

Ordering the RAM

For the upgrade, you will need the following RAM:

  • PC2700 DDR333MHz SODIMM RAM module.
  • 512MB or 1024MB (1GB).
  • 2.5-3-3-7 specification
  • Some luck

Micron/Crucial RAM
Micron/Crucial RAM

I seem to have had luck with an unidentified 1GB SIMM using Infineon chips, and a 1GB Crucial (probably) SIMM using Micron chips. The RAM I’m testing today was purchased from the eBay seller galaxyshoppingcn in Hong Kong. The listing is currently still available here, but obviously this wont last forever. Current price is £6.66 for a pair of SIMMs.

Infineon RAM
Infineon RAM

Opening the case.

To access the RAM slot on the ReadyNAS Duo, it is necessary to remove the two right hand screws highlighted in red in the following picture (borrowed from the manual).

Screws to Remove
Screws to Remove

Once these have been removed and stored safely, carefully place the ReadyNAS on its side on a soft surface with the long side face closest to the two screws facing upward. Place one hand flat on the long side face and hold the rest of the unit with the other. Push backwards (towards where the screws were removed from) on the long face and it should clunk backwards about 10mm or so with intermediate force. This side panel is very similar to traditional PC case side panels and so you should now be able to lift it off, exposing a single, occupied SODIMM RAM slot.

Mind the Gap
Mind the Gap

Removing the existing RAM

At the two ends of the RAM slot are silver coloured retention leavers. At the same time, push the end of the silver leavers away from the RAM SIMM until it releases and stands up further from the socket.

Released RAM
Released RAM

Take particular note of how the RAM sits in the socket at this point – the angle, and how much of the root of the RAM is within the socket. Note that the contacts on the edge of the RAM are almost hidden.

It should now be possible to withdraw the RAM SIMM. Avoid touching anything other than the edges of the (usually) green PCB and look after the SIMM as it is the only one you have which is guaranteed working!

Installing new RAM

Take your new, higher capacity RAM SIMM and place it in the socket in the ReadyNAS. Place it at the same angle as the previous SIMM was after you released it, taking notice of the alignment notch about one fifth of the way along the SIMM. Ensure that it is fully seated in the slot – this may require some pressure – the gold contacts are usually almost invisible when it is properly seated. Also see the “Released RAM” image above.

Once you are satisfied, push the highest edge of the RAM down so that it becomes parallel with the socket. It should click slightly at both ends as the latches slot home. If it presents any significant resistance, ensure that it was seated properly and try again. Consider fully removing and re-seating.

RAM in the Slot
RAM in the Slot

Closing the case

Place the removed side panel back in the location from where it was lifted off – approximately 10mm from the closed position. For reference, see the photo above titled “Mind the Gap”. Once it is sat flush, firmly close it back to its home position.

Depending on how confident you are of success, you could either re-install the screws now (taking care not to cross-thread them), or wait until testing is finished.

Checking that it is recognised

Connect an ethernet cable to your ReadyNAS, connect power and turn on the device as usual. Wait until all lights have stopped flashing and log into the device admin page as you usually do (for example http://192.168.1.2/admin if that is your ReadyNAS network address). If the ReadyNAS does not successfully boot, firstly ensure that the new RAM SIMM is correctly installed and try again, and then give up, re-install the original RAM (ensure /that/ still works) and go back to eBay to find another SIMM.

Home Screen
Home Screen

If everything is looking good at this stage, on the admin home screen, you should see reference to 1024MB of RAM and the string of numbers “2.5-3-3-7”. This means that the RAM is fully recognised and that it is running at the correct speeds.

Running a full memory test

Between this, and this websites, I put together how to undertake a full memory test and what to expect to see.

Starting the Memory Test

Note that the memory test will take a substantial amount of time, during which the fan will run at full speed. Only run the test if you have the time to leave it. For me, the test took approximately an hour and a half.

With the ReadyNAS Duo turned off, press and hold the power button without obscuring the two hard drive activity lights. You will be holding this button for approximately 25 seconds. Watch the pair of activity lights, after 5 seconds they will briefly flash – after the 5th flash, release the power button. The power button should continue to blink and initially you should see just the left light lit of the pair of activity lights. The fan will continue at full speed through the test.

Understanding the Lights

During the test, the power button will blink for the entire period. As the memory test goes through each of eight steps, the two activity lights will progress through the following pattern :

1-0, 0-1, 1-1, 0-0, 1-0, 0-1, 1-1, 0-0

Once finished, the third, single, central green status light will illuminate, with the two disk activity lights lit and the power light flashing… if successful. If the two disk activity lights are flashing, the memory test has failed.

The ReadyNas Duo will remain in this state indefinitely (useful if you run the test unattended). Poking the power button restarts the ReadyNAS.

If you have not already done so, re-install the case screws.