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CHAPTER FIVE
A Brief RAM/ROM Tutorial
ROM is...
ROM is an acronym for Read Only Memory. Since a
battery backed RAM Disk can be not only read from but
also written to, ROM Disk is a misleading name for a
battery backed RAM Disk. The reason we call it this is
because we used the GSs ROM Disk drivers to support the
battery backed RAM Disk. You see, the GS has built-in
ROM Disk drivers intended to support ROM chips loaded
with programs. For example, you might attach a card to
the memory expansion card that has AppleWorks loaded
into an EPROM. The AppleWorks program could be
loaded from the EPROM at a super high rate of speed.
However, the EPROM would be Read only Memory, and
no files could be saved to it nor could the program be
altered in any way. On the other hand, the RamKeeper
not only lets you load programs extremely quickly but also
lets you choose the programs you want loaded as well as
save files to it. Since ROM Disk is the name that the GS
supports, that is what we we call the battery backed
portion of memory that RamKeeper keeps alive.
The IIGS has a built-in ROM chip. This is a 128K chip
containing information about what the computer should
do when it is turned on. The ROM chip also includes
Applesoft Basic and the Control Panel program. This chip
was programmed by Apple when the computer was
manufactured and can’t be altered; the 128K memory is
not memory you can use for storing data.
RAM is...
RAM is an acronym for Random Access Memory. This is
the memory that can be both read from and written to --
the addressable (user useable) memory. GS memory
expansion cards use RAM chips and can range in capacity
from 256K to 8 Meg. (8 Meg is the maximum amount of
RAM allowed by the IIGS.)
Chapter Five - A Brief RAM/ROM Tutorial 35