I sent this early this morning, but it it must have gotten blocked
because of all the attachements...
All,
As everyone knows, the 6507 processor in the 2600 is really just 6502
with some address lines cut out. So, I was wondering what would happen
if I could access those other 4 address lines.
So, I got a 6502 and hacked it into a 2600. The result is 64K of
addressable space! What the heck to do with all that address space?
RAM! 32K of it!
http://www.baroquegaming.com/projects/superatari/super_atari.htm
My website (above) now has some pictures and a short movie. The movie
shows the part testing the RAM. The pictures show the board and how I
interfaced it to the 2600. Basically, I popped out the 6507 and plugged
headers into the socket. I also had to separate A12 between the
cartridge and the TIA/RIOT chips. This involved cutting a trace on the
board and running a jumper wire (the purple wire in the pictures) to the
board. The RAM and the 6502 are wirewrapped together with some glue logic.
In the new setup, the TIA and the RIOT chips are mapped to 0x0000 -
0x0FFF and the Cart ROM is mapped 0xE000 - 0xFFFF. For a couple of
cartridges I tried (like Adventure) this abreviated memory map still
works, and more importantly, so does a supercharger. The RAM is mapped
from 0x4000 to 0xBFFF.
So far all I have is a program that checks the RAM, so if anybody wants
to try out something that takes an obscene amount of RAM, let me know!
I have lot more plans like an RS232 interface and a boot ROM, so I will
keep you all updated..
Cheers!
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