What a mess!

But I guess that’s just the way I like it. :)

This time the SCPH-9002 modchip installation actually works.

I moved from the PIC12C508A to the PIC12F629.

The major practical advantage for me was that the PIC12F629 is Flash-based and reprogrammable, which made repeated programming experiments considerably less painful.

MultiMode3 programmed successfully and the console booted my test games.

The earlier failures also make more sense now.

The CD burner I had been using for test discs was faulty, and disc verification had not always been enabled or heeded.

So some of what I had been treating as potential modchip failure was actually bad test media muddying the diagnosis.

Successful modchip.

Successful games.

Questionable diagnostic process.

We got there in the end.

Sources