PsNee modchip installation guide
The PsNee modchip is a newer chip that has been under development during the last couple of years, and is still under active development. PsNee modchips should work with every version of the PlayStation 1. They can be made using many AVR processors, including the Arduino Uno, Arduino Pro Mini, ATtiny85, and ATtiny45. This guide covers everything you need to know about choosing, programming, and installing a PsNee 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 PsNee 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.
PsNee modchip installation diagrams
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
PsNee modchip drawbacks
The biggest problem with PsNee chips is that they aren’t very well documented (in terms of things like installation diagrams for every board revision). They also can be hard to find for sale.
This guide, along with my store, will help alleviate both of these issues by providing installation diagrams, and a place to purchase the chips.
PsNee modchip advantages
The greatest strength of the PsNee modchip is the fact that it’s much more modern than PIC based modchips. Using AVR chips means that programming a PsNee chip is much easier, and many people may already have something like an Arduino which can be used as a PsNee modchip.
Using more powerful processors allows the modchip to work with American, European, and Japanese PlayStation 1’s with a single chip, no need for a version for each region. It can even patch the SCPH-102’s BIOS to allow playing imports (previously this was only available with the OneChip). Note that this BIOS patch only works with ATmega based PsNee chips.
Going forward PsNee modchips will likely become the new standard modchip, especially as the PIC12C508A chip used for more popular chips like the MM3 reaches end of life.
PsNee modchip source code
If you’d like to program your own PsNee modchips you’ll need the source code. It supports the following microcontrollers:
- Arduino Pro Mini (8MHz, or 16MHz) – supported and tested
- Arduino Uno (8MHz, or 16MHz) – supported and tested
- ATtiny85 – supported, untested
- ATtiny45 (8MHz internal oscillator) – supported, tested
- ATtiny25 – supported tested
These chips fall into two categories, ATmega based chips, and ATtiny based chips. ATmega chips cost more, but allow for BIOS patching for SCPH-102 systems, as well as debugging for developers. ATtiny chips cost less, but lack those two features. ATmega chips are also considerably larger in size, making them more difficult to fit into a system when compared to the ATtiny chips.
I’m currently working on developing and testing modifications to the PsNee code to support full BIOS patching functionality with some of the ATtiny chips with more than 8 pins.
The source code is available on the PsNee Github page. It can be compiled very easily using the Arduino IDE.
Hello, I just ordered from you and succesfully modded my PsONE,
A tip for future installers, After soldering, my psone wasnt fully booting every time, the cd motor was spinning way too fast and not reading cds, what happened was that when I soldered the vias points, my wire went too long on the other side of the board and was touching the metal shield causing a short, after cutting the excess wire, no more issues!! excellent modchip!
This is probably a noob question, but is the PsNee a SOIC or MSOP/(T)SSOP pinout type? I want to use a breakout board for cleaner installs. I know the Mayumi v4 will support. Thanks!
There are multiple packages available for the chip. Page 207 of this datasheet has each package listed: https://ww1.microchip.com/downloads/en/DeviceDoc/Atmel-2586-AVR-8-bit-Microcontroller-ATtiny25-ATtiny45-ATtiny85_Datasheet.pdf
Hi, I bought the Psnee modchip and installed it n my Japanese PS1 SCPH-7000 but it is only playing original and backup japanese games only. Am I missing something?
Japanese systems past early SCPH-3000 systems have additional BIOS region locking. Meaning that even with a modchip you can only play Japanese region games. You either need to patch the games to be Japanese region, or swap the BIOS chip with an American BIOS chip.
hi, so a SCPH-1000 wouldn’t have any problems right?
Correct.
DigisPark is compatible to program?
Probably.
Is this possible to replace PSIO in the future? The reader emulation has become so popular since it was introduced in DreamCast and I wonder if this could do the same in the future, without depending on PSIO
If somebody develops a disc drive replacement type thing for the PS1 then it could be used instead of the PSIO, but at the moment the PSIO is the only SD card type game loader for the PS1.
Hi there. I just got the PSnee from you about a week ago. Thanks for the quick shipping. Im pretty noob with this and this will probably be a basic question, but I’d like to install this on what would be the easiest of my systems to say. I have SCPH 7501 March 1999, SCPH 1001 March 1996, and SCPH 101 OCT 2000, so if you could suggest which is probably the easiest to install the modchip in I’d appreciate it very much. I haven’t looked at the diagram/s yet, and I’m thinking the process might be somewhat streamlined throughout,… Read more »
SCPH-1001 and SCPH-7501 are similar difficulty. The SCPH-101 is a little harder to install in. I’d go with the SCPH-7501 since the SCPH-1001 systems tend to have pretty bad lasers at this point so you may have issues reading backups reliably.
Thanks a bunch for the reply William. That’s probably going to be my best bet. Lookin forward to getting this installed. 🙂
are there chips that are compatible with a 5500 model bios that i can get and flash a new bios? i don’t have a backup ps1 and want to put the american bios on my japanese ps1.
Are you talking about buying a replacement BIOS. There is this but I haven’t tried it personally: https://willsconsolemodifications.co.uk/ps1_replacement_bios.php
Hi I’m trying to use a psnee on attiny 85 without success .I already compile the psnee with arduino and I got a hex file to program with a tl866 programmer I chose program as a Intel hex after that I disabled ckldiv 8 fuse I’m installed in a ps one pm41 NTSC and doesn’t work I was thinking maybe the optical was bad but is not i installed a mm3 that I bought from you a time ago on eBay and that works.Any suggestions
I installed the TL866 Minipro Software on my computer and it does open the ino file for PSNee, but do I install it directly or do I have to install Arduino IDE in order to extract it?
You have to compile the PsNee .ino with the Arduino IDE, and then take the .hex from the build output directory and flash that. You also need to disable the clkdiv/8 fuse (all the other default fuses should be fine).
I’m not sure how to do that, and I don’t own a Arduino Board. I only installed the software but I keep getting an error.
You shouldn’t need an Arduino board. You need to install the ATtinyCore in the boards manager, select the chip you are using, and compile it using the verify button.
Never mind. I found it.
If you did end up installing it then it should show up in Tools->Board.
Did that. Getting Error Select a board.
You have to configure which version to use in the source code by uncommenting one of the define lines.
So the steps after installing the Attinycore is to uncomment the
#define ATTINY_X5 line
right?
I guess it worked as I have a hex file now. Thank you.
Yes, for the ATtiny version.
Hello William, I managed to do this via arduino nano. I have also tried this with an ATTiny45, but no luck. Can you please let me know if i am doing this right: I have an Arduino Uno and I am trying to upload via the IDE. I have used this pinout (- the capacitor): https://create.arduino.cc/projecthub/arjun/programming-attiny85-with-arduino-uno-afb829 I did not flash a hex file. 1.I can compile the hex file, but I cannot flash the hex file via avrdude. I get an error saying that the signature of the device (000000) does not correspond to the the signature of the attiny45.… Read more »
I haven’t done the programming with the Arduino IDE (but it should be possible to do so). I use a universal chip programmer where I can just directly flash the hex file and fuses to the chip. The device signature error usually means that there’s a problem with the connection to the chip. That could mean the wires are too long, or that one or more of them is in the wrong place. You’ll want to leave all the fuses as they are by default, except the clock/8 fuse (so it runs at full 8MHz speed). I believe that burning… Read more »
I have an USBasp V2 and I could also use that… form all the tutorials i have seen selecting the 8mhz internal from the arduino IDE and burning the bootloader should fix it… By the way, I used this as an example:
https://www.youtube.com/watch?v=Va2-4HYGK0Y
it worked with the arduino nano as modchip, but it won’t work with the attiny45 chip :((((
What kind of programmer are you using?
One of the TL866 programmers.