MM3 modchip installation guide

MultiMode 3, or MM3 modchips are very popular, and should work with every version of the PlayStation 1. They can be made using PIC12C508A, PIC12F629, and other PIC chips. This guide covers everything you need to know about choosing, programming, and installing an MM3 modchip into your PlayStation.

Guide structure

This guide is structured into several pages. It’s organized like this primarily so that comments can be more organized and useful for readers.

This page covers the MM3 modchip. It includes general information about the chip, and then links off to installation guides for each console model.

If you want more information about PlayStation 1 modchips in general check out this guide.

MM3 modchip installation diagrams

MM3 modchip

Below is a list of all PlayStation 1 motherboard versions, along with the console model numbers associated with them. You can get a good idea of what board you have by looking at the model number underneath your system (something like SCPH-7501).

To actually know what board you have you’ll most likely have to open up your console and look for the board version printed somewhere on the board (something like PU-22 or PM-41).

Once you know what board you have you can click on the board model and you’ll be sent to a page with the installation diagram.

  • PU-7
    • All SCPH-1000’s
    • Some early SCPH-1001, and SCPH-1002’s
    • Some early SCPH-3000’s
    • Some early SCPH 3500’s
  • PU-8
    • Most SCPH-1001, and SCPH-1002’s
    • Most SCPH-3000’s
    • Most SCPH-3500’s
    • All SCPH-5000’s
  • PU-16
    • All SCPH-5903’s
  • PU-18
    • All SCPH-5001’s
    • All SCPH-5500, SCPH-5501, SCPH-5502, and SCPH-5503’s
    • All SCPH-5552’s
    • Some early SCPH-7000, SCPH-7001, SCPH-7002, and SCPH-7003’s
    • Some early SCPH-7501’s
  • PU-20
    • Most SCPH-7000, SCPH-7001, SCPH-7002, and SCPH-7003’s
  • PU-22
    • All SCPH-7500’s
    • Most SCPH-7501’s
    • All SCPH-7502, and SCPH-7503’s
    • Some early SCPH-9000, SCPH-9001, SCPH-9002, and SCPH-9003’s
  • PU-23
    • Most SCPH-9000, SCPH-9001, SCPH-9002, and SCPH-9003’s
  • PM-41
    • Earlier SCPH-100, SCPH-101, SCPH-102, and SCPH-103’s
  • PM-41 (2)
    • Later SCPH-100, SCPH-101, SCPH-102, and SCPH-103’s


MM3 modchip drawbacks

The biggest problem with MM3 chips is how they base their timing on the internal oscillator within the PIC chips. Using the internal oscillator can sometimes cause the chip to become out of sync with the console when booting, meaning you’ll have to restart the console to boot.

Certain PIC programmers can also mess up the internal oscillator value when programming, which could be a problem if you are programming your own chips. Additionally it has been reported that certain batches of PIC chips have had problems with the oscillator value in the past.

MM3 modchip advantages

The MM3’s greatest strength is its compatibility and popularity. From my experience it is the single most popular PS1 modchip being used today. Because of this you’re more likely to find people who can help you if you are having problems installing your chip.

Additionally the MM3 is compatible with most PS1 consoles and can play anti modchip games if you install all seven wires. The only system that you definitely shouldn’t install an MM3 in is the SCPH-102 (install a ONEchip instead).

MM3 modchip source code

If you’d like to program your own MM3 modchips you’ll need the source code. Right now I only have the code for the PIC12C508A and the PIC12F629. If you have the code for other PIC chips let me know and I’ll add them to this post.

The MM3 chip has three different versions, one for each region. If you have an American system use the USA version, if you have a European system use the EUR version, and if you have a Japanese system use the JAP version.

  1. PIC12C508A
    1. MM3 PIC12C508A USA
    2. MM3 PIC12C508A EUR
    3. MM3 PIC12C508A JAP
  2.  PIC12F629
    1. MM3 PIC12F629 USA (assembly source)
    2. MM3 PIC12F629 EUR (assembly source)
    3. MM3 PIC12F629 JAP (assembly source)

I’ll have a tutorial on how to program these PIC chips in the future.

All MM3 chips I sell are preprogrammed.

Where to buy MM3 modchips

I sell preprogrammed MM3 modchips based on the PIC12C508A on my eBay store. I offer discounts using the eBay best offer feature if you are buying multiple chips at once.

In the future I may set up my own store on this website where I’ll sell chips for slightly less since I wouldn’t need to pay eBay fees.

I currently only ship chips to the United States. If you’re located in another country I recommend buying from EurAsia. They sell genuine chips for a good price, but shipping is fairly slow.

Where can I get premodded systems, or have my console modded?

I sell both premodded PS1’s, and MM3 modchip installation services on my eBay store. Premodded systems aren’t always available, but I can always buy and mod one if requested.

Premodded systems (may be out of stock): $69.99

Modchip installation service: $28.00 + shipping

More information is available on the linked listings.

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Felipe ChiericeWilliam QuadeMark Recent comment authors
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If I’m interested in trying to program my own mm3 mod chip, do you have a recommended PIC programmer? Did you buy one or make one from scratch? What software do you use for the .hex files, etc? How do I verify that it worked correctly, before soldering it to a PS1.

Thanks in advance. Love the site.

Felipe Chierice
Felipe Chierice

Hi Quade, nice guide!

I have a question, can I write the 12C508A program code into a 12C509A microcontroller, and use the same wire diagram? Thanks for your attention.