OK, I think the old 4 wire chips only need 3 wires in PSX 101’s and 9001’s , pins 1, 8, and 6. The pin 5 of the 4 wire mod is not compatible with these boards. The chip will work but it will only boot BACKUP CD’s and not original games. The 9001 had a jumper wire you could add to the board in place of pin 5 to fix original CD booting, the 7501 board as well, I think. I don’t know of any jumper for 101’s.
All that is fixed in newer chips. Have a look at these diagrams:
http://www.modchip.com/pictures.htm
All points for pins 1,8,5,6 should be pretty much the same no matter what chip, the 2 or 3 extra points are ONLY for the stealth mode.