[stella] 2600 bankswitched games on 7800 RAM cart

Subject: [stella] 2600 bankswitched games on 7800 RAM cart
From: Adam Wozniak <adam@xxxxxxxxxxxxxxxx>
Date: Sat, 19 Apr 2003 09:42:35 -0700 (PDT)
Ok, so a 7800 RAM cart should work fine with 2K and 4K 2600 games.

What about everything else?

It seems like you should be able to write a preprocessor that reads in
a binary for a bankswitched 2600 game and produces a new binary which
will run on a 7800 ram cart.

The preprocessor would follow the thread of control through the 2600
binary, remapping banks to different areas of RAM, and replacing things
like "$F000: LDA $1FF9" with "JMP $E003" and such.  Superchip and
RamPlus could be handled with a similar sort of remapping.

Bugaboos may occur in things like timing (LDA in the example above
is 4 cycles, JMP is only 3) and indirect and computed jumps (where the
PC is set or incremented in a way not obvious by simply examining the

Hopefully areas doing lots of bank switching won't be time critical.

For some bank switching schemes (FE) this preprocessor would be incredibly


adam@xxxxxxxxxxxxxxxx        http://cuddlepuddle.org/~adam/pgp.html
Will code for food.          http://cuddlepuddle.org/~adam/resume.html

"Fools despise wisdom and instruction." Proverbs 1:7 

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