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 |