This is the Mayumi 4 installation I used with a PIC12F629 on an SCPH-7502 PlayStation with a PU-22 motherboard.

Mayumi 4 installation points

There are eight solder points in this installation.

PIC12F629 Pinout

The mode sequence I recorded for this PIC12F629 build on the SCPH-750x / PU-22 setup was:

Strongest Mode -> Old Modchip Mode -> Disable Mode

Hold reset for around two seconds to change modes.

The configuration shorthand recorded with this build was:

WDT_OFF, ExtRC_OSC, MCLR_OFF

This page does not identify the exact HEX file or configuration word used, so the shorthand above is preserved as recorded rather than validated for every PIC12F629 port. Do not assume the same wiring or configuration applies to every PlayStation revision.

Credit and thanks to Mord.Fustang for the PIC12F629 port of the Mayumi code.

Sources