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Thread: Anyone know how to capture Motorola MCM6832 mask ROMs with a Data I/O Unipak?

  1. #1

    Default Anyone know how to capture Motorola MCM6832 mask ROMs with a Data I/O Unipak?

    I just received eight Tektronix 4051 and 4052 ROM Packs and I want to capture and upload the ROMs, but the 4051 ROM Packs have this MCM6832 2kx8 mask ROM that requires +5V, +12V and -12V.

    I've got a Data I/O with Unipak 2B, but I don't want to damage these ROMs.

    Anyone successfully read these mask ROMs?

    Thanks,
    Monty

  2. #2
    Join Date
    Mar 2013
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    Chaffee, MO
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    Monty,
    It should be no big deal. The MCM68A332 is pin compatible with the MCM68766, with the exception of Pins 20 & 21.
    These are the Chip Select Pins that are a Custom Program for the Specific Customer. For the MCM68A332 Pin 20
    is S1* (Active LOW) and Pin 21 is presently Unknown. You will need to try a Read with it LOW, then HIGH (pulled
    up with a 5K Resistor and see what condition allows a read of the data.

    The 1979_Motorola_Memory_Data_Book.PDF has both ROMS. (Bitsavers)

    I did a similar thing with the MCM68766 ROM and for a READ I only needed Pin 12 VSS (5V Common),
    Pin 24 at Vcc (+ 5VDC) and Pin 20 G* (Low for Chip Select), and the Data was clocked out on D{0..7}.
    Page 4-10.

    I used an Arduino, and that threw a small problem in the read of my Character Generator because some
    of the Data Lines were PULLED UP by the Arduino. The Character Generator only used 5 of the 8 Bits.
    I have that Document if you would like to read it. It shouldn't impact your data from your read assuming
    your are reading a full 8 bits.

    It's simple enough to do, and no big deal.


    Larry

  3. #3

    Default

    Have you seen this thread, one method is to dump via serial port:

    http://www.vcfed.org/forum/showthrea...ASIC-Simulator

    Regards,
    John

  4. #4
    Join Date
    Mar 2013
    Location
    Chaffee, MO
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    1,209

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    Monty,
    Any Progress?

    Thanks.

    Larry

  5. #5

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    Larry,

    I found a full MCM6832 datasheet in the Motorola MC 6800 Microcomputer System Design Data book, and compared it to the TI Memory data book TMS2716 datasheet.

    I got a tip that the TI TMS2716 had similar +5V, -5V and +12V voltage rails and size, but different pinout, so I created the following diagram and pin conversion list:



    I used a plugboard to connect one of the Motorola ROMs to a set of sockets that I put into the Data I/O Unipak 2B 24-pin ZIF socket, and used the 23/28 family pinout code for the TMS2716.

    The Data I/O posted an Error 31 "Excessive Current Drain".

    I rechecked my wiring and looked at the datasheets again - the TMS2716 had similar current on -5V and +12V but almost no current on +5V compared to the Motorola, so I disconnected the jumper from the Data I/O pin 24 and powered the Motorola ROM from a separate supply to +5V. I still got the Error 31, so I stopped.

    I haven't tried your Arduino program.

    Monty

  6. #6

    Default

    I ohmed out my wiring and found a couple of wiring errors and a bad jumper.

    I was able to read eight of nine MCM6832 ROMs! They were all over 40 years old!

    See my post:
    http://www.vcfed.org/forum/showthrea...062#post592062

    My RS-232 Printer Interface ROM Pack had a different 1KB Motorola ROM MCM68308. The pinout is more standard - and close to the Intel 2708, so I tried reading it with the Motorola pin 18 pulled out of the Unipak socket and connected to +5V as shown in the service manual schematic - but my Data I/O indicated the device was reversed. I checked the device orientation and it was correct.

    I may try to read the device with an Arduino using Larry's code - but not this weekend.

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