Expanding Gameboy Cart SRAM

It's not that hard actually..

I found a chip on digikey, ISSI IS62C256AL-45ULI, $2 - I was able to solder every single pin to the same spot on the cart except for 1 pin, and then connect the new address lines to the memory mapper.. (MBC1-MBC5)

Here is the process I performed in expanding my Kirby's Dreamland 2 Flash cart from its normal 8KB RAM to an added 32KB RAM.........

Ok here's the old Cart loook

This 1 has the Hyundai HY6264A.. but I've seen other RAM types that have the same pin config..

So like I was saying, ISSI IS62C256AL-45ULI, 32KB RAM that is the same pin config as the gameboy ram designs...

Gameboy cart RAM on left... Our RAM on the right...

HOOKING IT UP

Remove the old RAM chip either by carefully sawing off the pins with a razor blade, or desoldering.....

Then, simply take your new RAM chip, 

1)bend PIN26 so that it will not touch the board, 

2) Solder all pins in place!!

3) Wire pin 26 and pin 1 to your MBC's A13 and A14 RAM address lines!! For an MBC1 like mine, that would be pins 6 and 7, whose pins names are EA0 and EA1... solder that bitch!!

I then wrote a program that writes to each 8KB ram bank to ensure that the new RAM is working!! Of course, the program also ensures that the data remains on the chip after powering down (battery packed SRAM bitch!!!)

P.S. The program works, but I discovered that for some reason the first byte of the first RAM bank never saves properly.. but the first byte of the other RAM banks do save just fine.. soooo odd..... here's a pic from when I saving at 00:A000 (first byte of first RAM bank).. notice the square (fail!)

So that's it... I dunno if anyone found this useful.. The only reason why I did this is because I have my pokemon pinball cartridge which is MBC5. I want to make a 32Mbit cart with 32KB RAM. but I don't have ZELDA for that, so I wanted to see if I could expand the 8KB RAM on the pokemon pinball... I still have to get that thing rolling... I really need someone to help me make a PCB of a TSOP AMD 40-pin flash memory that simply routes each pin to a wirehole to make things easier for me.... ANYONE.. ANYONE!?!?!?