I wonder how many bytes will get corrupted overtime due to the RAM being mounted on a giant antenna ;)


Yup, I was actually very wary of building the adapter this way exactly for potential corruption/noise/crosstalk issues, but I decided to try nonetheless.
The biggest problem, I thought, was ...

There, mod released, I closed up my SCPH-7502 and played around with it for a day. Still working fine, games still running, all RAM still addressable.

Hope someone else can have fun with it: PS1_PU22_8MB_mod

You will need moderate soldering skills, nothing too hard here, but a steady hand is a ...

Woot!
Found the issue! I swapped A8 with A10, and now I get the whole 8MB, test is passing too!

Stack = 807FE000
Test the PlayStation RAM
Original code by Trimesh

Generating fill pattern...
0x80200000
0x80210000
0x80220000
0x80230000
0x80240000
0x80250000
...
0x807A0000
0x807B0000
0x807C0000 ...

Yep, no idea if I'm setting them wrong, but here is what I get with

ResetCallback();
AddSIO(115200);

printf("RAM_SIZE before 0x%04X\n", *(volatile uint16_t*)(0x1F801060));

SetMem(8);

printf("RAM_SIZE after 0x%04X\n", *(volatile uint16_t*)(0x1F801060));

*(volatile uint8_t*)(0x80200000 ...

Greetings everyone,
I have decided to attempt an 8MB RAM mod on a PU22, not because I lack PU18 units, but just for fun and experimentation.
Given that the PU22 uses a single 2MB DRAM IC, I decided to build a small flexible board to be soldered in place of the IC, with pads to solder the same DRAMs ...