Using 27C512 PROMS on a CO70208 cartridge board?

[oracle_jedi]

Paranoid Little Man has some games he adapted to run off cartridge on his website.

 

The files are 128K, so after splitting they are 64K.  The CO70208 board only seems to accept 27C64, 27C128 and 27C256 chips.

 

In an older thread, @atarifan49 stated that you had to add a 27LS08 chip to the board to make it support the larger PROM chip, but didn't offer up a schematic. 

 

 

 

Does anyone have that mod to allow the larger PROM chips to be used on the this board?

 

 

[ParanoidLittleMan]

It can be done simpler, with 2 diodes instead LS chip:

 

And for those with 27C256 EPROMs - you can split those 64 KB files in 2 32 KB with some hex editor, for instance.

[oracle_jedi]

Thanks for the schematic @ParanoidLittleMan  I'll try to find some time this weekend to see how to mod the board with these extra diodes.  I don't have the board in my hand right now but I don't recall the resistor being there either.

 

If I get it working I'll post an update.