Re: Looking for the elusive "Expanded VisiCalc v1.76a, for the Commodore 8096"

Rhialto wrote
> If you put a jumper in the right place on the expansion connector, you
> can replace the option ROM socckets with RAM from the "extra" 32K.
> So you can have $8000-$AFFF all as RAM.

Thanks a lot for your reply.  The information you've provided helped a lot
:-) This is probably what the soft-rom loader programs are talking about
when they say "Flip front switch to R/W". So I tried it after  setting
$9000-$9FFF as RAM on vice and the program continued where it used to hang.
Now it loads the ROM data to $9000, so there is some progress now :-) The
problem is after loading the ROM data, the program asks user to switch it to
read. I can't emulate that on vice. It seems there is a way to make ram read
only probably shorting something inside. 

I was even able to load visicalc with one type of soft-rom loader but it
hangs when it realizes that the rom data is writable. 

Also, i've realized it has to do with the program poke'ing and peek'ing
address 634.
634 must be 0 for the loader program to work. then it sets it to 15 and 16
or 60 while and after loading rom.
I guess 634 has to do with I/O (maybe tape? I'm not sure) but both on vice
and on my 8096, when I do a print peek(634) the result is 255 and those rom
data loader programs want 634 to be 0 or something else (but not 255) to
start. So I do a poke  634,0 before I start the rom loader program and it
works. 

I have to test this on my 8096. so for that I need to figure out the pins
for setting $8000-$AFFF or maybe hopefully just $9000~$9FFF as RAM also I
need to find out how to make it read only as well.

I wonder if this RAM hack would be possible with peek and poke to do it by
adding some connections inside so that shorting and un-shorting could be
done programmatically so it would be possible for some part of ram to behave
like rom upon request. I'm thinking maybe that 634 was about that.

I would really appreciate any help on address 634(dec) and this R/W and
Read-only hack.
Thnx.





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