|
 |
Tech Tips: Thanks For The Memory
|
|
Mac memory problems...and how to fix them
Why won't my Mac II/Mac IIx recognise all of its RAM?
Why can't my Mac 'see' all its memory in OS 6?
Why isn't my extra RAM showing up?
How (and why) do I use 'Mode32'?
How can I increase an application's memory allocation?
Is Virtual Memory worth the effort?
Why can't I use Virtual Memory on my machine?
The Mac Plus can support up to 4Mb - why won't mine?
[Q]: Why won't my Mac II/Mac IIx recognise all of its RAM?
[A]: Both the Mac II and the IIx use proprietory PAL RAM which, while looking like regular 30 pin SIMMs is actually different (but provides a performance increase). Standard SIMMS can be installed but only up to 4Mb - anything above this can't be used. If this is the case, check that you have the correct SIMMs installed.
[Q]: Why can't my Mac 'see' all its memory in OS 6?
[A]: OS 6 is limited to being able to use a maximum of 8Mb - anything above that can't be used unless you use a third party solution.
[Q]: Why isn't my extra RAM showing up?
[A]: Assuming that you're not running OS 6 (which is limited to 8Mb) make sure that you have 32-bit addressing switched on in the Memory Control Panel. Restart and you should be fine. Note: Some machines may require the Mode32 patch to access memory above 8Mb (see the next question to find out more).
[Q]: How (and why) do I use 'Mode32'?
[A]: Mode32 fixes various problems with certain machines (SE/30, Mac II, Mac IIx, Mac IIcx, Quadra 700). Because of a combination of 24 and 32 bit code, these machines (which are classed as having 'dirty' ROMs) cannot access memory above 8Mb. Mode32 solves this problem and copying it into your Extensions folder and restarting should do the job. If you have less than 8Mb of RAM then Mode32 will make no difference.
[Q]: How can I increase an application's memory allocation?
[A]: Increasing an app's memory allocation can allow you to open bigger documents. To do this, close the application, select its icon and then use the Get Info command from the File menu. In the 'Memory' box at the bottom of the dialog, enter a new 'Current Size' - increasing this by 200k-300k should be enough.
[Q]: Is Virtual Memory worth the effort?
[A]: Ideally you should always try to install more physical RAM (it'll be far quicker than Virtul Memory) but if this isn't possible then Virtual Memory is your only other option (without having to pay for something like RAMDoubler). Try to keep your Virtual Memory set so that it is no larger than the amount of physical RAM - any higher and your machine may spend far too much time thrashing the hard drive.
[Q]: Why can't I use Virtual Memory on my machine?
[A]: Make sure that you're running Mac OS 7. If you are then it may be your actual hardware that is causing problems. The Mac II, LC and anything based on the 68000 CPU (i.e. the REALLY old machines) won't allow Virtual Memory to be used. Note: The Mac Plus, Classic and SE can be made to allow Virtual Memory by using software from Connectix but it's really not worth the effort.
[Q]: The Mac Plus can support up to 4Mb - why won't mine?
[A]: The Mac Plus does support up to 4Mb of RAM but you have to do some surgery (otherwise the maximum it can 'see' is 2Mb). Open the case and remove the main board (disconnect the internal power and floppy cables). With the board in front of you and the ports at the top, locate the R8 resister (top left, just below the interrupt and reset switches - it should have 'RAM SIZE' printed above it). This resistor needs to be cut at one end (or removed totally). Once this is done, put your machine back together and you should have access to all 4Mb!
|
|
