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273 lines
12 KiB
Markdown
273 lines
12 KiB
Markdown
---
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title: Sony PlayStation (PS1/PSX)
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x-toc-enable: true
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...
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The PlayStation is a computer like any other. It ought to run all Free Software
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if you want it to, and you can!
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<div class="specs">
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<center>
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<img tabindex=1 alt="Sony PlayStation (PSOne) console" class="p" src="https://av.canoeboot.org/playstation/psone.jpg" /><span class="f"><img src="https://av.canoeboot.org/playstation/psone.jpg" /></span>
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<img tabindex=1 alt="PCSX-Redux Open BIOS" class="p" src="https://av.canoeboot.org/playstation/openbios.png" /><span class="f"><img src="https://av.canoeboot.org/playstation/openbios.png" /></span>
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</center>
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| ***Specifications*** | |
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|----------------------------|------------------------------------------------|
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| **Manufacturer** | Sony Computer Entertainment Inc. |
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| **Name** | PlayStation |
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| **Variants** | PlayStation, PSOne, Net Yaroze |
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| **Released** | 1994 (Japan), 1995 (Worldwide) |
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| **CPU** | MIPS R3000 @ 33.8688 MHz |
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| **Graphics** | Custom 3D processor by Toshiba, 1MB Video RAM |
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| **Sound** | 16-bit custom Sony SPU |
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| **I/O** | CD-ROM, analog Audio/Video, Serial, Parallel |
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| **Memory** | 2MB EDO DRAM |
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| **Architecture** | MIPS I instruction set (RISC) |
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| **Original boot firmware** | Sony PS1 BIOS (USA/JPN/EU) |
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| **Flash chip** | 512KB Mask ROM |
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</div>
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Introduction
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============
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This uses the free/opensource BIOS developed by the PCSX-Redux team, which you
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can learn more about here:
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<https://github.com/grumpycoders/pcsx-redux/tree/main/src/mips/openbios>
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Build from source
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-----------------
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Canoeboot's build system provides automation for this. Please use the latest cbmk
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revision [from Git](../../git.md).
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First, please make sure you have build dependencies. The build logic in cbmk
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has been tested on Debian 12 (x86\_64) and you can do this for example, as root:
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./mk dependencies debian
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The `arch` and `parabola` dependencies should also work nicely, if you want
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to replace `debian` with one of those in the above example; you need to get the
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cross compiler (mipsel one) from the AUR, which you will see when running e.g.:
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./mk dependencies arch
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If you have another distro, or you're unsure, the PCSX-Redux project also
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provide generic instructions for other distros. Please see:\
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<https://github.com/grumpycoders/pcsx-redux/blob/main/src/mips/psyqo/GETTING_STARTED.md>
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When you have the dependencies, including mipsel cross toolchain, you can
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just do this in cbmk:
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./mk -b pcsx-redux
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This commonly only builds the BIOS part. If you want to build all of PCSX-Redux,
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you can, but cbmk does not provide automation for this.
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Installation
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============
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If all went well, you should see `openbios.bin` located
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under the `bin/playstation/` (within cbmk). Alternatively, you may be using
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a release *after* Canoeboot 20240612 that has it pre-built. Either way is fine.
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The `openbios.bin` file is your new BIOS build.
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Emulators
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---------
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Most PlayStation emulators rely on low-level emulation to execute the real BIOS.
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The Open BIOS by PCSX-Redux (as distributed by Canoeboot) can also be used, and
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boots many commercial games, plus homebrew.
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These emulators can boot many commercial games, with varying degrees of
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compatibility, and they can also boot any homebrew/opensource games that you
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might develop yourself, or that others have written.
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Simply load your `openbios.bin` file into the emulator, using the instructions
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provided with your chosen PlayStation emulator. You can even freely
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redistribute this BIOS, because it's free software (released under MIT license),
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which is a major advantage over Sony's original BIOS.
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Hardware
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--------
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Not yet tested by the Canoeboot project, but the PCSX-Redux developers have
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stated that it will work on the real console. *It should be noted that the Open
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BIOS does not seem to implement a memory card save handler at present; you can
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save and load games, in-game, but there is no built-in program for copying
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and deleting saves between memory cards.* From reading the documentation, it
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seems that this is essentially a very well-engineered proof of concept that
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happens to boot a majority of games; some polishing is still needed to make this
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really useful on a real machine.
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The main usefulness of the Open BIOS is that it's under an MIT license, and
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therefore legal to distribute; anyone wishing to use an emulator can use a
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compiled copy of the Open BIOS, and distribute it freely without trouble.
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You also do not get to listen to music CDs. The quirk with memory cards is
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easily mitigated in an *emulator*, because you can simply create different
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memory card images for each game you play.
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It would be nice if a memory card manager program were available, to make this
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BIOS much more polished, but a number of games have been tested and it's more
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or less fully reliable in most cases.
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Game compatibility
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==================
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The upstream maintains a compatibility list, here:
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<https://docs.google.com/spreadsheets/d/1UNGs7uYb8viAbm7YJaf1CR4dkgX7ZzntUdcowGsjcVc/edit?pli=1&gid=772799649#gid=772799649>
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NOTE: Google Docs, but an option exists on there to export it for LibreOffice
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Calc. The list is provided as a spreadsheet.
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Remarks about hardware
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====================
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Modern NOR flash can be used. You specifically want a TSOP-32 SMD/SMT type device,
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one that operates at 3.3v (tolerance 2.7 to 3.6v), organised into 512KB blocks,
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for example 512KB x8 is a common part, for example [SST39VF040](https://eu.mouser.com/ProductDetail/Microchip-Technology/SST39VF040-70-4C-WHE?qs=I6DYTe5pEPUDs7BrdNtR9w%3D%3D).
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Look here:
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<https://oshpark.com/profiles/mi213>
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This person has designed PCBs that can be used to add a NOR flash, adapting to
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the pinout of the playstation BIOS. Some early launch model PlayStations used
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a 40-pin chip but most later ones soon after and to end of life were 32-pin.
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This page only sells adapters for use with 32-pin boards.
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For most boards, the one you want is probably the `PS1_Flash_Bios_(A)` one.
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We do not yet provide instructions for how to install this on real hardware, in
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the Canoeboot project, but this can be done at a future date.
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Other mods (hardware)
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===============
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Video timings
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-------------
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The Open BIOS will not implement any DRM, so it's possible that you might boot
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out of region games. In an emulator, this is no problem, but it can prove
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difficult on hardware in a number of situations.
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The purpose of these kinds of mods *on hardware* is typically that the user
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wants to remove all DRM. Well, there's something many people overlook: video
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timings out-of-region are often wrong on these machines. The GPUs have two
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clock inputs (early launch models only have one clock input): one for PAL and
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one for NTSC. More info could be written here at a later date but these consoles
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typically don't have a PAL GPU clock on NTSC consoles, and vice versa. You can
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correct this.
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Look up the PS1 "dual frequency oscillator" mod. Without this mod, NTSC games
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will run slightly slower than they should and have the wrong colours, when booted
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on PAL consoles (and vice versa); RGB SCART can be used to mitigate the colour
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issue, but not the timing issue. The oscillator mod is the only solution for the
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timing issue.
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The PAL GPU clock is roughly 53.2MHz, and divides by 12 to create the 4.43MHz PAL
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subcarrier/colorburst signal; this is needed in composite video for example.
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The NTSC GPU clock is 53.693175MHz, and divides by 15 to create the 3.58MHz NTSC
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subcarrier/colorburst signal; ditto, this is used for NTSC composite video.
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On a PAL playstation, Sony hardwired 53.2MHz to both inputs, and on NTSC, wired
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53.69MHz to both inputs; that means on NTSC machines, PAL games will run with
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a 3.579545MHz colorburst signal, and on PAL consoles running NTSC games,
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the colorburst would be 3.55MHz. *Some* people suggest hardwiring a 4.43MHz
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clock to the video dac/buffer on PAL consoles, thus creating what is called
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a "PAL60" signal, but this is ill advised; ditto wiring 3.58MHz to it (NTSC50).
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On *most* consoles except very early launch/debug models, and *very late* slim
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models, the PAL clock is pin 192 on the GPU and NTSC is pin 196 on the GPU.
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The Dual Frequency Oscillator mod uses a programmable oscillator and taps into
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the video mode signal off of the GPU to know whether PAL/NTSC is used; it
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switches the master clock hooked up to both inputs accordingly.
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Another method is to *cut* the line going to the NTSC pin on a PAL console,
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and wire a 53.69MHz oscillator (at 3.3V, with the output through a 220Ohm
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resistor) directly to the pin; on an NTSC console, do the same but cut 192
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and hook up 53.2MHz to it. The Dual Frequency Oscillator method is easier and
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therefore recommend, but you can do this other method, which I call *DO* (Dual
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Oscillator. Because it's two oscillators!)
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By fixing the timings in this way, your region-free console will also have
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correct timings, thus maximum game compatibility, and colours will always be
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correct no matter what video cable you're using.
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Modchips
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--------
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If using hardware, you will probably still want a modchip. Many proprietary
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modchip firmwares exist, such as Old crow, MultiMode3 and Mayumi; these run on
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PIC chips e.g. PIC12C508A. A special *OneChip* firmware is often used on PAL
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PSOne Slims.
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There is a *free/opensource* modchip type called PsNee, which is what Canoeboot
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recommends:
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<https://github.com/kalymos/PsNee>
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Unlike the other modchips, PsNee runs mostly on Arduino-type boards. You can
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find more info on its GitHub page.
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Although not yet tested by Canoeboot, it might be possible to have both the
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Sony BIOS and Open BIOS, by stacking them on top of each other, soldered pin
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for pin but leaving the OE/CS pins floating; then, wire up a switch that turns
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one chip or the other off, so that you can pick which BIOS you want at boot.
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This might be useful, in case you run into any compatibility issues with the
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Open BIOS.
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A modchip is still desirable, to mitigate copy and region protection in the
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original BIOS; it may still be required when using the Open BIOS, but this has
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not yet been confirmed by the Canoeboot project.
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More hardware testing is planned, but the Open BIOS works perfectly in emulators.
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Give it a try!
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Boot games on SD cards
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-----------------------
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The [PicoStation](https://github.com/paulocode/picostation) project provides
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free firmware for RP2040 devices, which you can solder into a modboard which
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then emulates the PS1 CD drive. It then lets you boot software (including
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many games) from an SD card instead of a CD, using disc image files, on a
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real playstation (the picostation replaces your CD drive).
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Not only is this useful in a development context, but it can also be used when
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your CD drive has worn out and no longer reads discs properly.
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Final remarks
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-------------
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Combined with PsNee and PicoStation, the Open BIOS from PCSX-Redux team will
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turn your 90s PlayStation into a very hackable machine. There is
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also PSXSDK (which is also free/opensource) allowing for libre game
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development, also known (somewhat ambiguously) as "homebrew" development. The
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fact that these old consoles were designed to boot proprietary games is mere
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coincidence; they are
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simply computers, fully reprogrammable and as such, Canoeboot is happy to provide
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this support, for the Sony PlayStation
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Credit
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======
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Thanks go to the PCSX-Redux team for their excellent work reverse engineering
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the Sony PS1 BIOS.
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The two photos shown are as follows:
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* PSOne Slim photo was taken from here (the one provided by Canoeboot is
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scaled down and cropped, with color levels enhanced for better contrast):
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<https://commons.wikimedia.org/wiki/File:PS_One_with_LCD.JPG> -
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released under the terms of Creative Commons Attribution-Share Alike 3.0 Unported license
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* The cube screenshot is of the PCSX-Redux Open BIOS in operation, on an emulator.
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PlayStation, PS1, PSOne and other terms are the trademark of Sony Interactive
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Entertainment. Canoeboot is in no way affiliated to Sony Interactive
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Entertainment; this page is not an endorsement of Sony Interactive Entertainment,
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nor do they endorse Canoeboot.
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PCSX-Redux developers are not affiliated with Canoeboot in any way. We simply
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integrate their Open BIOS into Canoeboot because their work is awesome.
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