Re: ROM 3 IIgs, SCSI cards, and DMA

[supertimer@aol.com (Supertimer)]

"Jason Whorton" <jason@microxl.com> wrote:

>Hello.  I have an Apple High-Speed SCSI Card in my Apple IIgs ROM 3.  I am
>considering the purchase of a Sirius RAM card.  The FAQ says that if I had
>8MB of RAM on it, I would have to turn off the DMA.  How much RAM could I
>install on it and keep the DMA turned on?  Which would be better, 8MB of RAM
>and DMA turned off or using DMA and the maximum amount of RAM that can be
>used while keeping the DMA turned on?

4MB on the card (plus 1MB already on the IIGS motherboard) making 5MB
would be the total you could have with DMA on.  If you have a RAMFast
card, then you can have the full 8MB and still keep DMA on.

I have to disagree with David, although I respect his opinion.  8MB can be
very fun.  I can show you some audio and video files you can download
that can be accessed/created with 8MB (you'll need ShrinkIt! GS and a hard
drive to unpack them, of course).  As for DMA, if your IIGS is accelerated
with a TWGS, turning DMA off makes less of a difference than you would
imagine.

>    How much faster would my IIgs system be with a new 1MB RAMFast SCSI card
>and the 8MB of RAM compared to using the Apple High-Speed SCSI Card and 8MB
>of RAM with DMA off or with DMA on and the maximum amount of RAM?
>    Thanks in advance for any information on these questions.

Not much.  Look at the debate thread some two years ago on the issue.
http://www.dejanews.com/ DejaNews.  Go there and do a Power Search.
Put "DMA" without the quotes in the Subject field and "comp.sys.apple2"
in the Forum field.  Look through the results.