The System can get big, but unless you have a large number of fonts it
should never be larger than 3MB under System 7, and much less than
that under System 6. There are several reasons the system will appear
to grow. Here are the most common ones.
System 6
--------
System 6 acts differently from System 7 in that its RAM heap is a
fixed resource which needs to be constantly managed if you have
many INITs and/or fonts installed. HeapFixer from CE Software is a
simple utility which allows setting the System 6 heap size. The basic
rule under System 6 was to keep the System showing 25% free (that is,
white) space in the "About this Macintosh..." dialog.
These are the contributors to System File size under System 6:
* Fonts and INITs - both contribute to System memory requirements.
* Bit mode - System 6 is a 24-bit operating system. This means that
unless a System 6 Macintosh has a third-party INIT enabling 32-bit
addressing (such as Maxima from Connectix), all installed physical
RAM over 8MB will show up as additional System memory.
System 7
--------
Under System 7, the operating system maintains more extensive guards
against running out of memory. Basically, the Cache (configured in
the Memory Control Panel) controls how much space to allocate to the
System. Memory management was improved under System 7, and users no
longer need to worry about the "25% free space" concept. The System
will typically take up 95-99% of its allocation, leaving only a small
bit of white space in the "About this Macintosh..." graphic. This is
nothing to worry about. If you get messages that you need more
memory, then you can allocate more in the form of Cache, or you should
consider adding more RAM if there's none available for additional
Cache.
Here are the factors that contribute to a large System File size under
System 7:
* Fonts - Previous to version 7.1, each installed font drove the
system's RAM requirements up.
* Cache - The amount of RAM Cache allocated in the Memory control
panel is included in the overall figure for System RAM
requirements. To correct: set the Cache to 256K or less, and
restart.
* Extensions - Each extension obtains its own amount of RAM and
contributes to a large System RAM requirement.
* Bit mode - if the Macintosh has more than 8MB of physical RAM
installed and is set to run in 24-bit mode (under the Memory Control
Panel), then the excess over 8MB shows up as System memory. To
correct: set the Macintosh to run in 32-bit mode.
* RAM Disk - Macintosh computers supporting the Apple RAM Disk
(Quadras and later) can create a RAM disk using a portion of their
installed physical RAM. All RAM used in the RAM Disk shows up as
System memory in the "About this Macintosh.." dialog.