PsNee is an open source stealth modchip for the original Playstation.

It runs on modern microcontrollers like the Atmega32 and ATtiny. You will need some way of programming it. I used an Arduino Uno board with the ISP sketch.

Preparing the Arduino Uno board

Flash an Arduino Uno board with the ISP sketch:

File -> Examples -> 11. ArduinoISP -> Arduino ISP

Uncomment:

// #define USE_OLD_STYLE_WIRING

Configure and compile the PsNee sketch into a hex file

Uncomment

#define ATTINY_X5

Sketch -> Export compiled binary

Wire the ATTiny to the Arduino Uno ISP

Wire up your chip according to the Arduino ISP instructions

Arduino Uno ATtiny
Pin 10 Pin 1
5V Pin 8
Pin 13 Pin 7
Pin 12 Pin 6
Pin 11 Pin 5
GND Pin 4

If you want a flash progress indicator, wire an LED + resistor from PIN 5 to ground.

Write the program

avrdude -C~/Library/Arduino15/packages/arduino/tools/avrdude/6.3.0-arduino17/etc/avrdude.conf \
-v \
-pattiny45 \
-cstk500v1 \
-P/dev/cu.wchusbserial1420 \
-b19200 \
-Uflash:w:./psnee.ino.hex:i \
-U hfuse:w:0xDF:m \
-U lfuse:w:0xE2:m

Of course, sub out your serial as appropriate. The same can be done for ATtiny85 by:

-pattiny85 \

That’s the hard part over with! Crack out the soldering iron and follow the install diagrams. I recommend William Quade’s site.