grochoci@mentor.cc.purdue.edu (Paul Grochocinski) (04/24/91)
What I have is a fully populated Apple Memory expansion card for my GS. The one that came with it. Is any of the memory on this board used as DMA? If not, can I get it to be or am I stuck with it(with the exception of getting a new board)? If so, how do I use it? I have tried copying Battle Chess to the RAM and boot it from there but I don't notice any real difference in the timing.
gwyn@smoke.brl.mil (Doug Gwyn) (04/24/91)
In article <11079@mentor.cc.purdue.edu> grochoci@mentor.cc.purdue.edu (Paul Grochocinski) writes: > What I have is a fully populated Apple Memory expansion card for my GS. >The one that came with it. Is any of the memory on this board used as DMA? You're operating under a misconception. The RAM itself is neither "DMA" nor "non-DMA"; DMA refers to a method of accessing the memory by other devices. Some RAM expansion cards for the IIGS malfunction under some types of DMA access, which is probably where you got the notion. I think Apple's own expansion card has no problem when accessed via DMA. >I have tried copying Battle Chess to the RAM and boot it from there but I >don't notice any real difference in the timing. Use of a "RAM disk" (emulation of a block storage device using RAM) can speed up "disk" I/O but not computation. Once the program is loaded it runs at the same speed no matter where it was stored. (There are some minor exceptions, not worth discussing at this level.)
toddpw@nntp-server.caltech.edu (Todd P. Whitesel) (04/24/91)
grochoci@mentor.cc.purdue.edu (Paul Grochocinski) writes: > What I have is a fully populated Apple Memory expansion card for my GS. >The one that came with it. Is any of the memory on this board used as DMA? If Apple's board can always be used with DMA peripherals. >not, can I get it to be or am I stuck with it(with the exception of getting a >new board)? If so, how do I use it? I have tried copying Battle Chess to the >RAM and boot it from there but I don't notice any real difference in the timing DMA only works for moving stuff into and out of the computer. Copying something to the RAMdisk may use DMA for the copy, but once the files are on the RAMdisk then the CPU has to shuffle things in memory itself. You do not have to worry about DMA unless you have a DMA peripheral like the Apple High Speed SCSI card, the RAMfast, or the Visionary. Todd Whitesel toddpw @ tybalt.caltech.edu