Is it possible to hack a PS1 to read iso from sd card

Discussion in 'Modding and Hacking - Consoles and Electronics' started by littlezump, Mar 27, 2015.

  1. littlezump

    littlezump Newly Registered

    Joined:
    Mar 27, 2015
    Messages:
    2
    Likes Received:
    0
    I have a ps1 9001 with a broken disc drive, is it possible to install a sd card reader into the ribbon cable/ laser assembly to play isos?
     
  2. Kappa

    Kappa Peppy Member

    Joined:
    Aug 12, 2014
    Messages:
    346
    Likes Received:
    35
  3. citrus3000psi

    citrus3000psi Housekeeping, you want towel?

    Joined:
    Nov 8, 2013
    Messages:
    1,051
    Likes Received:
    419
    ps-io will require a parallel port...I think the 9001 still have the solder points on the board, so you could hard wire ps-io directly to the machine. Don't get your hopes up for ps-io just yet. It always seems they are "close" to being done. Then another 6 months pass. I would just get another ps1. They are dirt cheap.
     
    Last edited: Mar 30, 2015
  4. littlezump

    littlezump Newly Registered

    Joined:
    Mar 27, 2015
    Messages:
    2
    Likes Received:
    0
    Yeah, I really don't feel like shelling out the cash for that when/ if it comes out. I was looking for a cheaper and more hands on approach. Getting another PS1 isn't an issue, just wanting to see if it could be done.
     
  5. Greg2600

    Greg2600 Resolute Member

    Joined:
    Jun 23, 2010
    Messages:
    937
    Likes Received:
    112
    I doubt you'll find a cheap solution for systems like 3DO, PS1, or Saturn.
     
  6. wilykat

    wilykat Site Supporter 2013

    Joined:
    Mar 25, 2012
    Messages:
    991
    Likes Received:
    45
    For the time being, it's much cheaper to grab a modchip and burn CD-Rs. Any SD to ISO solution could set you back a few hundred dollars for the equipment to program chips and some books on programming chips like Xilink, as well as understanding Playstation. Not to mention a few spare PSX would be needed as one may fry a system.
     
  7. TriMesh

    TriMesh Site Supporter 2013-2017

    Joined:
    Jul 3, 2008
    Messages:
    2,354
    Likes Received:
    778
    It's possible, but much more complicated than it might seem at first glance. The first issue is that an .ISO file only contains the data payload of the track, and the low level encoding on the CD (which is what you would need to emulate) has a lot of other stuff in it you would need to emulate (subcode streams, sync marks, etc) - you would also need to generate the table of contents at the start of the disc, since the CD controller reads that first and won't do anything if it can't decode it. Generating the data is not that big a problem - you could certainly do it with a MCU + FPGA combination, and probably just with a suitably fast MCU. Since the fastest these old consoles worked at was 2x, the required data rate is:

    Raw sector: 2352 bytes
    C1C2 overhead: 784 bytes
    Subcode: 98 bytes
    Total: 3234
    Sector rate at 2x: 150/sec
    Effective raw channel data rate: 485.1kB/sec
    Encoding overhead (EFM + merging bits): 17/8
    Raw channel bit rate: 8.2467Mbps

    This is not a difficult number to hit at all with modern silicon - the only bit that might stress the MCU is the cross interleaving needed by the error correction, but that's also exactly the sort of thing that FPGAs are really good at - the same thing applies to the scrambling for the data payload - quite expensive in software, but trivial to implement in hardware.

    The rest of the design is fairly simple - you would need some signal conditioning for the drive signals from the controller - the spindle drive would control the rate you generate the EFM stream and the sled drive would move the emulated playback position. The second might require a bit of fiddling, since the drive firmware will generally apply a correction to the sled drive based on the current disc position, and you want to invert that correction in the emulator firmware. The sled logic also needs to generate an emulated home switch signal, because when the drive initializes it will drive the optical pickup towards the spindle, and stops when it hits the switch.

    You also need some circuits that generate the correct photodiode signals from the drive - on a typical 3 beam pickup these consist of 4 outputs, two of which carry the read data and focus information and the other two of which carry the tracking info. The tracking is easy to simulate - just take the tracking drive signal (normally applied to the lens actuator) and directly generate fake EF signals from it. For the PSX, you would also need to have a facility to inject the copy protection signal into this circuit, since the drive controller won't boot the disc without it.

    The focus is a bit more complicated because it's on the same pins that the read data is, but you could use a similar approach, only this time with the focus actuator control signal.

    The last set of connections on the pickup are for the laser diode - in the case of the PSX, you could just leave them open, since it doesn't monitor for diode failure, but a more general approach would be to design a laser diode simulator that monitored the diode current and produced a fake monitor diode output based on it. It might also be useful to detect if the commanded laser power was at an operational level since this provides useful drive status information.

    I've written some of the FPGA code (in Verilog) for this, and I'll try to dig it out.
     
  8. master991

    master991 Enthusiastic Member

    Joined:
    Jun 4, 2012
    Messages:
    597
    Likes Received:
    28
    Yeah, and i think it will be more likely functional than psio. I don't think if it's a correct example, but look at ODE for ps3, if they do with it, why not with the psx :p
     
    Last edited: Mar 28, 2015
  9. TriMesh

    TriMesh Site Supporter 2013-2017

    Joined:
    Jul 3, 2008
    Messages:
    2,354
    Likes Received:
    778
    Strangely, the PSX is probably slightly harder to make an optical drive emulator for than the PS3 - If you pull apart a PS3, the connection between the optical drive and the rest of the system is basically ATA (PATA on the old ones, and SATA on the new ones) - and (apart from the undocumented security stuff) the drive protocol is very standard. The interface on the PSX is entirely specific to that device, so you have to write something that's also entirely specific.

    I think the approach that PSIO uses is a good one - it's emulating the drive at the hardware interface level, so it's basically replacing the CD DSP + CD Interface + Mechacon CPU on the console with it's own implementation. This is a rather higher level method that the direct drive emulation I was talking about above, so it avoids the hassle of having to generate extra data only to have the drive strip it all out again. It's main problem is that it uses the expansion port to get access to the CD controller signals, so ti won't work on the 900x or the PSone without a lot of soldering.
     
  10. wilykat

    wilykat Site Supporter 2013

    Joined:
    Mar 25, 2012
    Messages:
    991
    Likes Received:
    45
    tl;dr let someone else finish their work and buy PS-IO when it's available. You will save a lot of time trying to emulate PSX's propriety CD hardware.
     
  11. master991

    master991 Enthusiastic Member

    Joined:
    Jun 4, 2012
    Messages:
    597
    Likes Received:
    28
    Yes, but it is an emulated thing, like xa audio, and honestly, it has compatibility issues, It's even real and secure that will be improved and maybe resolved in the future , but honestly i don't like this idea\project, because IMHO it's like an emulator on a real machine with not accurate (perfect it's impossible) execution of game....
    Instead an optical emulation which can give a near perfect execution with games, because we have to emulate only the optical drive block, and not the other blocs of the machine which can gave always issues....

    Look the CD switch idea, solder another wire only to emulate lid close\open. I don't see where is the plug and play idea honestly.... Unlike a cd drive emulator....
    I hope i was clear...

    EDIT:
    @wilykat:
    More choice, more alternatives, always better. I don't see why someone must stop a project only because someone is working on the same one (which is a different approach)
     
    Last edited: Mar 28, 2015
  12. Kappa

    Kappa Peppy Member

    Joined:
    Aug 12, 2014
    Messages:
    346
    Likes Received:
    35
    If this is the case your better off buying a few ps1's getting them chipped and just use those. Because nobody is going to want to recreate what the psio team has done so far unless there is one that is up and coming that hasn't been announced yet.
     
  13. master991

    master991 Enthusiastic Member

    Joined:
    Jun 4, 2012
    Messages:
    597
    Likes Received:
    28
    For me it's a better alternative than psio....
    It's just a personal opinion.....
    If all psx of all earth die someday, so... there are always emulator and psp\ps2\ps3 etc XD
     
    Last edited: Mar 29, 2015
  14. Kappa

    Kappa Peppy Member

    Joined:
    Aug 12, 2014
    Messages:
    346
    Likes Received:
    35
    We won't need emulators when psio becomes a thing, certainly not in our lifetime anyway :)
     
    Last edited: Mar 29, 2015
  15. kyo86sg

    kyo86sg Intrepid Member

    Joined:
    Jul 23, 2012
    Messages:
    699
    Likes Received:
    52
    I am still having faith on this PSO thingy...its have been truly a while.......... perhaps a loooooong while more to come.
     
  16. crans

    crans Rising Member

    Joined:
    Aug 16, 2014
    Messages:
    68
    Likes Received:
    1
    psio is one device id love to give a spin. i have been watching it for some time now and 89% done
     
  17. MottZilla

    MottZilla Champion of the Forum

    Joined:
    Feb 1, 2006
    Messages:
    5,072
    Likes Received:
    112
    I prefer the idea of something that plugs in where the normal drive does and simulates it as you were detailing earlier. It's just infinitely more appealing to be able to plug a device in and have it work, especially if it can avoid any compatibility issues that the PSIO method may have.

    Although anything that works well even if not perfect is alot better than nothing.
     
    Last edited: Mar 30, 2015
  18. Comp1demon

    Comp1demon Spirited Member

    Joined:
    Jul 14, 2006
    Messages:
    124
    Likes Received:
    1
    PSIO is in beta now!!
     
  19. bacteria

    bacteria I am the Bacman

    Joined:
    Apr 8, 2008
    Messages:
    978
    Likes Received:
    61
    If it doesn't sell cheaply though I can't see it will have any interest for buyers. £20 or less including postage at most.
     
  20. proarturs

    proarturs The force is with me

    Joined:
    Dec 23, 2013
    Messages:
    820
    Likes Received:
    49
    I would estimate the price to be triple of that.
     

Share This Page