ROM 3 IIgs, SCSI cards, and DMA

["Jason Whorton" <jason@microxl.com>]

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?
    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.

Thank you,
Jason Whorton
http://www.microxl.com/oldcomputers/main.html



021- How is DMA set for SCSI cards with 8MB RAM cards on the GS?

     DMA needs to be turned off with the Apple HS SCSI card or the RamFAST
revision C card.  It does not need to be turned off with the RamFAST
revision D
card (differentiated by being half sized).  All Sequential Systems RamFAST
cards are revision D as are late model CV Tech cards.  It is the RamFAST
revision D that is designed to DMA into any RAM card, even 8MB models. It
was
made around the time of the CV RAM 8MB model that turned into Sequential's
RAM
GS Plus, but functions just as well with the Sirius card.


Thank you,
Jason Whorton
http://www.microxl.com/oldcomputers/main.html