[A83] Re: extra storage
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[A83] Re: extra storage
> I figure that interrupts could be used effectively for this purpose. When
> you would want to recieve a file from storage, just hold down a certain
> combination of keys (why not 2nd-link?) and the interrupt program would
> fire. Why not install an interrupt program in $9872. Joe Pemberton
claims
> that this is 768 bytes of RAM intended for ASM programs (for the 83 and
the
> 83+???) and 256 (NOT 257 - see my next post) bytes would be used for the
> mode 2 interrupt table. This leaves around 512 bytes for a driver /
browser
> program, etc, even a simple shell that could copy and run programs from
> flash.
>
> In summary, the way to obtain files from the external memory doesnt have
to
> take up program ram and the external memory itself can be relatively dumb,
> simplifying design.
>
> Jeff
>
There is a problem with using such space for TSR's. It will work fine, as
long as no other assembly programs/applications are run that overwrite that
memory area (even though any good assembly program should do an IM 1 at the
start just in case). But if another assembly program does overwrite that
ram, then you're screwed.
Also - $9872 is only a 768 byte buffer on the 83+. It corresponds to
savesscreen, i believe - a buffer that is only present on the 83+. You
could use the APD buffer, but you would have to disable the APD and write
your own code to APD (so the user's batteries aren't eaten up) Again,
though, you're screwed if another ASM program is run and overwrites the
memory.
The solution would be a keyhook. I've never done much with APPs.. perhaps
somebody on this list can help out.
- - Joe P
References: