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Re: DMA 4 meg v. 8 meg

On 5/5/2011 1:21 AM, David Empson wrote:

Michael Black<et472@ncf.ca>  wrote:


On Wed, 4 May 2011, KP wrote:


I have a 4 meg RAM card in the memory slot of my ROM 03 IIgs.  I have
often heard that only the first 4 megs of expansion-card RAM is DMA-
compatible.  Can somebody explain what DMA actually is?

Does this mean that AppleWorks v5.1 will only recognize 5 megs (1 meg
motherboard RAM + 4 meg expansion card RAM) even if I put an 8 meg
expansion RAM card in the memory card slot?

Does this mean that the second 4 meg of expansion card RAM is useful
only as a RAM disk, and not as memory for programs to access, in order
to store long documents that the user is editing, graphics being
opened from disk, sounds being edited, HyperStudio stacks, etc.?


I see the specific question wasn't answered.

It won't mean a thing for your purposes.

Unless you have something that takes control of the Apple bus in order to
directly control the RAM, lack of DMA won't matter to you.


And for a IIgs, the only cards I can think of which use DMA are the
Apple High-Speed SCSI card, and the RamFAST SCSI card. If you don't have
either of them, you don't need to worry about DMA.

Is anyone else aware of any other DMA-capable cards that are likely to
be used in a IIgs?
The Carte Blanche card. As for how likely they are to be used on a IIgs, I might be the only one. 

Charlie