Re: Any non-memory cards for IIgs memory expansion slot?

[Roger Johnstone <rojaws@orcon.net.nz>]

In <slrnch6hdl.m1k.usenet@gaia.roc2.gblx.net> Dan Foster  wrote:
> In article <qh4qni35fc.fsf@ruckus.brouhaha.com>, Eric Smith
> <eric-no-spam-for-me@brouhaha.com> wrote:
>> From the hardware reference, it doesn't look like the slot would be
>> easily usable for anything but memory, but there were a lot of very
>> creative people building peripherals.
> 
> I honestly don't see how one could use the mem exp slot on a GS for
> anything other than memory accesses (whether RAM or ROM).
> 
> Comparing the pinouts on page 50 of the IIGS Hardware Reference manual
> (mem exp slot) and page 173 (I/O exp slot)...
> 
> One can see that essentially, the mem exp slots only has pins to deal
> with memory selection, refresh, transfer... whereas the I/O exp slots
> has pins for DMA, IRQs, phase 0/1/2 clocks for synchronization, ready
> assert, etc.
> 
> Probably other assumptions hardcoded such as in the slotmaker and Mega
> II, and so forth... I'd love to be proven wrong, but I just don't see
> how one could possibly make it do something other than mem stuff for 
> the mem exp slot.
>
> -Dan

Memory-mapped I/O of course :o)

But as you said the normal Apple bus slots are *much* better for 
everything except memory, especially since they provide ROM space for 
drivers.

-- 
Roger Johnstone, Invercargill, New Zealand
http://vintageware.orcon.net.nz/
________________________________________________________________________
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