This article discusses the reinitialization of the RAM disk on the platinum colored Power Macintosh G3 at restart.

Note: This article only applies to the platinum G3 computer. The Power Macintosh G3 (Blue and White) computer has a software change that allows it to save the contents of a RAM disk through a restart, and a setting in the Memory control panel to decide whether to save the files through a shutdown.

The PowerMac G3 Read Me document on the Power Macintosh G3 CD states:

"The RAM Disk on the Power Macintosh G3 computer will be reinitialized on every restart or reboot. Any data you have stored on a RAM Disk should be copied to the hard drive before a restart or shutdown. The RAM Disk feature should only be used to store data and applications which will be used between restarts and shutdowns."

This was a design choice during the development of the Power Macintosh G3 computers. These systems make use of faster, industry-standard memory called synchronous dynamic random access memory (SDRAM), which adds to both their economy and their availability. The Power Macintosh G3 incorporates a new memory controller called "Grackle" that can support both extended data out (EDO) and SDRAM which have different refresh cycles.

On previous computers, as soon as the memory controller came out of reset (after restarting the computer) it would generate memory refresh cycles. However, since Grackle supports both EDO and SDRAM memory which have different refresh cycles, Grackle will not begin memory refresh cycles until it is configured at startup. The length of time between restart and when Grackle is configured can exceed the period which SDRAM can retain its contents without refresh. Hence the SDRAM can be corrupted and thus result in a corrupted RAM disk after reset. The design choice was not to preserve the RAM disk across restarts to prevent the possible corruption of the data on the RAM disk.

Note: Although the Grackle memory controller supports both EDO and SDRAM DIMMs, Apple has tested and qualified only SDRAM for use in Power Macintosh G3 systems.

For additional information on working with a RAM disk, refer to article 58260: " Power Macintosh G3 (Blue and White): Read Me "