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Commodore 1541 disk drive emulator - SD card

Discussion in 'Retro & Arcade' started by GumbyNoTalent, May 8, 2018.

  1. GumbyNoTalent

    GumbyNoTalent Member

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    https://cbm-pi1541.firebaseapp.com/
     
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  2. HyRax1

    HyRax1 ¡Viva la Resolutión!

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    Will be interesting to compare the compatibility of the emulation against the Ultimate II+ cart.
     
  3. elvis

    elvis Old school old fool

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    I saw a project that did this via DOS over serial, but by all accounts timing issues prevented it on more modern computers.

    Will be interesting to see how the RPi GPIO handles the realtime need (I'm assuming that's what the "custom firmware" bit is).
     
  4. nic55

    nic55 Member

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    Just ordered components to build a cable, keen to see how this goes :D

    My c64 has been more of a tinker project than a system I really want to dedicate resources to at the moment. This could be a good way to finally get some software loaded on the thing and see what it has to offer. very nice find!
     
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  5. Vanne

    Vanne Member

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    Please respond back with how this goes. Very interesting..
     
  6. nic55

    nic55 Member

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    I was hoping for it to be my project for the weekend, after ordering (little bird electronics) I got an email that there's a 7 day wait on the logic converter.

    Hopefully next weekend!
     
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  7. flu!d

    flu!d Never perfect, always genuine

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    I saw this on Particles BBS, sounds like the same project?

    [​IMG]
     
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  8. nic55

    nic55 Member

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    That looks like the same project.

    Even longer wait on parts by the looks :(
     
  9. nic55

    nic55 Member

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    Finally all the parts had arrived and I had some time to build the cable late last night.

    After fighting with a failing SD card reader, a folder of corrupt C64 disk images and not knowing where the hell I put my c64 power plug I finally got double dragon to load, where I promptly discovered only the up direction on my joystick works.

    The cable itself was very easy to make, I opted to use a DIN socket so I could use the original C64 serial cable. This way the C64 end looks original and the emulator can be stashed behind a monitor. Some CAT5 from the DIN socket to the level converter, then an old IDE cable soldered on to the other side of the level converter can be plugged straight on to the pi.

    Double Dragon loaded suprisingly quick, but I don't have an original disk to compare it to. I'm grabbing the latest TOSEC today so I'll have a few more things to try out but I'll need to source another SD reader as well.
     
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  10. callan

    callan Member

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    Just a caution: I had some trouble using CAT5 as a Commodore serial cable (with an uSD/IEC device). It suffered from ringing for some reason, and corrupted data going through it. It might just have been that I picked the wrong pairs to use or something.

    Interesting project!

    Callan
     
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  11. akashra

    akashra Member

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    Okay, but what if I want to go the other way: Say I have a few hundred C64-formatted disks and have a two 1541s sitting around but want to retrieve the data from them...

    Yes, this is a real problem I have to resolve in the coming months/years.
     
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  12. nic55

    nic55 Member

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    Thanks for the heads up, I'll keep that in mind if I start seeing problems. I used solid CAT5 and only used 1 wire from the brown/orange/green pair, the blue pair I've used both for GND and ATN_OUT (pins 2 and 3) so that might help keep problems away.

    I remember seeing a reasonably simple schematic for connecting C64 disk drive to a PC. Or you could use an emulator like this to copy from the real drive to emulated image.
     
  13. elvis

    elvis Old school old fool

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    Bump... anyone tried this out yet? Apparently an overclocked Pi Zero W works OK too?
     
  14. nic55

    nic55 Member

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    Not on a zero, had it running on a pi3+ perfectly fine.
    Had a lot of trouble with corruption in the beginning but after switching the pi to an ATX PSU that all went away, assuming it was an issue with my usb cable/wall adapter.
     
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  15. elvis

    elvis Old school old fool

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    Interesting. I wonder if it was noise or under ampage (causing the CPU to slow down)? Those Pis sure to get power hungry sometimes.

    Finding good quality power supplies for them that can feed them the 2.5-3A they need at the top end can be tough. Even ones that advertise 2A seem to only be capable of about 1.5.
     
  16. power

    power Member

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    there's already something like this for the Atari 8-bit line i'm surprised the C64 is this far behind (or am i? ;) )

    The SIO2SD for those wondering what i'm prattling on about.
     
  17. nic55

    nic55 Member

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    I reckon so, when you connect to the pi's HDMI the display outputs each cycle and hi/low signal being emulated, the timings looked to be out of sync when issues were occurring and after switching PSU timings all looked to be in sync/the same.


    Just found a nifty little case to make up as well
    https://www.thingiverse.com/thing:2953000
     
    Last edited: Jan 9, 2020
  18. oculi

    oculi Member

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    are these harder to emulate than an Amiga disk drive? cause I think they (emulators) have been around for quite a while
     
  19. elvis

    elvis Old school old fool

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    Not difficult, but the timing has to be spot on. For RPi hardware it's been about having the grunt to make sure it always keeps up and doesn't lag behind what the C64 expects.

    I was just watching this video, and there's a good demo there where he switches from an RPi3 to an RPi1B, and you can see what happens on a non-overclocked 1B where it falls over. He then adjusts the clock and cache speed of a few things, and it loads fine after that.

    Jump to 14:40 to see the Pi1B fail, then from there the overclock and success.

     
    Last edited: Jan 9, 2020
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  20. flu!d

    flu!d Never perfect, always genuine

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    Have you still got your Atari?
     

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