Re: Real Speed of GS RAM slot?

[dempson@actrix.gen.nz (David Empson)]

In article <37hp3q$9dk@er3.rutgers.edu>, Kid <neiderma@er3.rutgers.edu> wrote:
> 
> Does the IIGS RAM card area run faster than 1MHz?  Just thinking
> that it woul dbe nice to have combination RAM and SCSI controller
> or somesuch...

Yes, the RAM slot runs at the IIgs's "fast" speed (2.8 MHz).

Any I/O device using the slot would have to be accessed outside the
normal RAM address space, i.e. in bank $80 to $DF, or $E2 to $EF.  It
would have to detect its address by monitoring the bank address on the
data bus, and would not work reliably with other DMA devices (except
possibly the RAMFast SCSI card).

The RAM slot doesn't have many of the control signals available on the
standard slots, and doesn't have all the power rails.

I very much doubt it would be able to do DMA itself, unless it did
something horrible like ABORTing the processor and forcing it to
re-execute instructions.

Another possibility would be for a dual card system: a standard slot
card with another card in the memory expansion slot, and a direct
connection between them.
-- 
David Empson
dempson@actrix.gen.nz
Snail mail: P.O. Box 27-103, Wellington, New Zealand