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drum machine rom replacement

Discussion in 'General Electronics Discussion' started by sneakyalien, May 24, 2010.

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  1. sneakyalien

    sneakyalien

    3
    0
    May 24, 2010
    Hi,I am wondering if any electronic wizards out there can give me some advise on an idea i have?
    I have an old yamaha drum machine that has dated drum sounds in its rom,the rom is in the form of a cartridge that plugs into the back of the drum machine,I would love to replace these dated drum sounds with modern drum sounds and was wondering if it is possible to read the data(drum sounds)from the existing rom and replace it with new data(modern drum sounds) and program them onto a comparable eprom and then put the eprom into the cartridge.

    I have opened the cartridge and there are two chips,
    chip 1 is a M5M23C100-512P 645100
    chip 2 is a M5M23C100-513P 643102

    Both chips are made by Mitsabishi.

    I presume the two chips hold the drum sounds as there are 28 drum sounds so I'm guessing 14 drum sounds each chip.
    I would be happy with 14 new drum sounds so if only one rom is needed thats fine.

    Does anyone know anything about these chips and is what I'm proposing possible or am I dreaming.

    Would love any info on this,
    Thanks for your time,
    Steve.:)
     
  2. Resqueline

    Resqueline

    2,848
    1
    Jul 31, 2009
    M5M23C100-XXXP is a 28-pin DIP N-MOS General Purpose Mask Programmable ROM.
    It is 128k Bytes with 8 bits per word. Access Time is 250ns. It has 3-State outputs & a Chip Select input. Max. power dissipation is 165mW.
    It should be possible to read them out with an EPROM-burner, and to find & burn new EPROM's. Interpreting the contents (or getting new sounds) is another story though.
     
  3. sneakyalien

    sneakyalien

    3
    0
    May 24, 2010
    Hi,thanks very much for the reply,it sort of gives me hope that this may be a feasible project.
    I am looking at getting the wellems eprom system but don't know if this will read the Roms.
    I was hoping once the contents of the Roms were read I could read them into a audio editing software called soundforge as raw binary data(Soundforge allows for this).

    I know this is probably all far fetched and I'm living in cloud cookoo land but I definitley want to try it.
    I have limited electronics knowlege(i'm new to electronics but fascinated by it) and realise this may be too advanced for my skills but hopefully the technical bods on this site will give me some guidance and help.
    At the very least I may learn something even if this project is just a pipe dream.
    Thanks once again for the information and your time,it is really appreciated,.
    All the best,
    Steve.
     
  4. Resqueline

    Resqueline

    2,848
    1
    Jul 31, 2009
    There's no telling how the data are stored, whether it's in a wave format or some kind of synth format, and if the bit order is nominal or "random". You'll just have to try.
    Then there's a question if they have bothered with programming a checksum into the PROM. Car chips have that, but there it's vital that the contents are uncorrupted.
    Good luck!
     
  5. sneakyalien

    sneakyalien

    3
    0
    May 24, 2010
    I believe the drum machine uses something called awm which is Yamaha's Advance Wave Modulation and the drums are encoded in 12 bits according to the drum machines spec in the manual.
    Is there a way of finding comparable Eproms to the M5m23's?
    Steve.
     
  6. Resqueline

    Resqueline

    2,848
    1
    Jul 31, 2009
    Ok. 12bit data means you have to figure out if the most significant byte comes first or last (of the two prom bytes you have to read out for each full awm byte).
    I figure it's less likely that the two bytes (nibbles?) are stored one on each chip.
    I found a datasheet here for one of its cross references (TC53C1000).
    My initial thought of using the common 27C1000 turns out to be not so trivial since it has 32 pins and so would need some adaptation.
    The M5M has a chip enable that you can program for either active high or active low (you'll need to find out which). The EPROM's are exclusively active low afaik..
    However you might be able to buy the original PROM variety off the net somewhere. Do a search (and include all the cross ref's, so there is some work involved).
     
  7. zephyrin

    zephyrin

    1
    0
    Nov 7, 2012
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