Apple Macintosh System 7.5 - Manual (Page 53)

Memory in System 7.5
Why do programs sometimes seem to run out of memory even on computers with lots of
available RAM?
Each application program sets aside a preset amount of memory when it’s
opened. You can see the memory size by using the Get Info command in the
Finder. You can increase a program’s memory size by typing a larger amount
in the “Preferred size” box.
The amount of memory available for opening a given program is limited by
the amount of RAM already in use by the system software and other open
programs.
Which Macintosh models can use virtual memory?
Any Macintosh with a Motorola 68030 or 68040 microprocessor can use
virtual memory. See the technical specifications for your computer for more
information.
Macintosh computers with the Motorola 68020 can be upgraded with a paged
memory-management unit (PMMU) processor to use virtual memory.
How much free space do I need on my hard disk to use virtual memory?
The hard disk must have free space equal to the total amount of memory you
want (RAM plus virtual memory), plus additional space for documents you
save while virtual memory is turned on.
For example, if you wish to work with 16 MB of memory and your Macintosh
currently has 8 MB of RAM installed, you will need to have free disk space
of at least 16 MB.
Is virtual memory compatible with current versions of application software?
Virtual memory is compatible with most Macintosh software products. Some
programs and other software may need upgrading to take advantage of virtual
memory. Check with the program’s manufacturer.
Is virtual memory compatible with CPU accelerator boards?
Some accelerator cards work or can be modified to work with virtual
memory. Check with the manufacturer. Accelerator cards for the Macintosh
Plus, SE, Classic, Portable, and LC computers do not work with virtual
memory.
51 Performing the Group Upgrade