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Thread: reading out mask rom with promdate

  1. #1
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    reading out mask rom with promdate

    Hello,

    I have an old drum machine from witch i like to extract the sample data thats stored in 2 mask roms, eventually the idea is to replace the stock samples with new ones but before i invest in a eprom programmer i like to see if the data extracted can be made readable.
    I came across the promdate program that seems like a good place to start. I'm new to teensy so please excuse me for the obvious questions. There is not much documented about the promdate project, tho all necessary comments are given in the code i definitely need some guidance modifying adres and data pins and if possible make it teensy 3.2 compatible.


    Fist thing first Teensy, like said i have a teensy 3.2 from another project, promdate is written for teensy 2.0++ but has some hints in the makefile for older teensy boards. The rom i want to read has 18 adres pins and 15 data pins so 33 pins i need to configure. Do i need a teensy 2.0++?

    Also from the data sheet of the rom, i cannot figure out if i am able to read the data with a 3.3v teensy (i need to read up on roms in general).

    Prom date like to source code can be found here:
    https://trmm.net/PROMdate

    Mask rom data sheet:
    http://retrocdn.net/images/c/ca/MB83...eet.pdf#page=1

    all pointers are much appreciated.

  2. #2
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    Quote Originally Posted by bernie View Post
    Hello,

    I have an old drum machine from witch i like to extract the sample data thats stored in 2 mask roms, eventually the idea is to replace the stock samples with new ones but before i invest in a eprom programmer i like to see if the data extracted can be made readable.
    I came across the promdate program that seems like a good place to start. I'm new to teensy so please excuse me for the obvious questions. There is not much documented about the promdate project, tho all necessary comments are given in the code i definitely need some guidance modifying adres and data pins and if possible make it teensy 3.2 compatible.


    Fist thing first Teensy, like said i have a teensy 3.2 from another project, promdate is written for teensy 2.0++ but has some hints in the makefile for older teensy boards. The rom i want to read has 18 adres pins and 15 data pins so 33 pins i need to configure. Do i need a teensy 2.0++?

    Also from the data sheet of the rom, i cannot figure out if i am able to read the data with a 3.3v teensy (i need to read up on roms in general).

    Prom date like to source code can be found here:
    https://trmm.net/PROMdate

    Mask rom data sheet:
    http://retrocdn.net/images/c/ca/MB83...eet.pdf#page=1

    all pointers are much appreciated.
    Making a Teensy-based PROM-reader would be interesting for it's own sake, but you have a specific goal.
    Perhaps you could rent or borrow a reader. There may be retro-computing enthusiasts near you who can help.
    This would reduce the preliminaries to -at most- the acquisition/construction of an adaptor PCB for the many-pinned, SMD devices you are using.

    Data from the PROMs should be usable, unless the original programmers(s) used some sort of compression.

  3. #3
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    Thanks for the reply, About the data, it looks like some sounds are interleaved between the two roms, Also on the board there is a 16bit dac and a 8 bit dac. I dont know the reason for this. considering the possibility that concessions where made in the design of the machine, i do see the advantage of using a arduino mega or teensy, although i cant really elaborate this :S.

    I would definitely reconsider getting a genuine eprom programmer, but if the code mentioned and the pin configuration of 2.0++ permit me to use Teensy 3.2, I would like to give it a shot. The eprom is 40pin dip and using the smd header pin-out wond be a problem.

  4. #4
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    As long as you have enough pins to get to A[0..17] and D[0..15], you can do it: that's 34 pins, plus /CE
    Using the /BYTE line, you would need 18+8+/CE+/BYTE = 26
    Adding an 8-bit address-latch would use 8+8+/CE+/BYTE+latch = 19
    Like I said, interesting for it's own sake. Good luck!

  5. #5
    Senior Member Jp3141's Avatar
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    Nov 2012
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    There is a sufficient amount of digital IO on T 3.2 etc. This IO is 5 V tolerant -- i.e. it survives 5 V being applied, but can only output 3.3 V. The ROM uses 5 V, but the datasheet indicates that the input threshold spec is 2.2 v, so it likely will work.

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