Re: IIGS addressable space limit

["Bryan Parkoff" <BParkoff@satx.rr.com>]

    No, it won't be possible.  65816 can only go up to 16MB space.  It may
be possible to expand from 8MB to 12MB, but ROM design will not allow to
exceed 8MB.
    If you rewrite your own ROM for Apple IIgs that excludes GS/OS routines,
it may be possible to expand up to 16MB.
    Remember 65816 can only use 24 bit addressing that can handle 16MB
addressing.  I wish to redesign 65832 that will have 32 bits supporting 48
bit addressing that will handle 4 GB, but 65832 is the same with 65816
except only accumulator, registers, etc can handle 32 bits, but 24 bit
addressing is the same.  :-(


--
Yours Truly,

Bryan Parkoff
BParkoff@satx.rr.com
"Hellfire" <nospam@dontwantit.net> wrote in message
news:Y_mG8.4020$ym2.2810878055@twister1.starband.net...
> Does anyone know if all 16 address lines can be used on the memory slot? A
> IIGS with 64MB would be nice, but I have always heard that the max
> addressable memory was 8MB. Is the upper portion of memory reserved for
> anything? Or does the ROM just not support it? If anyone knows, please let
> me know.
>     By the way, I am nearly finished with my 8MB memory card design. So
far
> it uses only 4 4Mx4 SOJ's and a handful of gates. When it is tested, i
will
> post the schematics. The nice thing is, it can be built with only about
$30
> worth of parts and a 16MB SIMM (to scavenge for DRAM's).
>     Thanks in advance for any help!
>
>     -Regards, Matt
>
>
>