Re: Adding ram to ROM03 GS

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

Tony Mori <tonym@netrunner.net> wrote:

> Correct me if i'm wrong:
> 
> 
>   Apple IIgs, ROM03, 1MB RAM on-board
>                      4MB RAM on OrangeMicro RamPak4GS
>                    
>  EQUALS -----------  5MB RAM Total

5MB of fast RAM plus 128KB of slow RAM (5248KB total).

However, the Orange Micro might be an old card which pre-dates the ROM
3, and uses a non-standard method to decode the addresses (e.g. by
looking at the bank address directly instead of using the row select
signals provided by the motherboard).

This would mean that the card effectively only provides 3MB + 128KB (the
rest overlaps the motherboard address space and is therefore
unavailable), and the total memory size would be 3MB + 1MB + 256KB
(4352KB).  The maximum RAM disk size in this case would be 4MB (the
bottom 128KB of fast RAM and the 128KB of slow RAM are not available for
use by the RAM disk).

This certainly fits your symptoms.  It could be proved by putting the
same card into a ROM 1 IIgs: if the memory size reported is exactly the
same, then I'm right.

If this is the case, then the card probably won't work with DMA enabled
on your Apple HS SCSI card.


Another possibility is that there is some faulty RAM on your card.  Try
running a memory test program on it.

-- 
David Empson
dempson@actrix.gen.nz
Snail Mail: P.O. Box 27-103, Wellington, New Zealand