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Thread: Replacing 82S181 bipolar PROM on RLV12 with EEPROM

  1. #1

    Default Replacing 82S181 bipolar PROM on RLV12 with EEPROM

    I replaced 82S181 on RLV12 with AT28HC64B-70SU EEPROM instead of obsolete 82S181.

    One of 82S181 bipolar PROM on RLV12 was broken, many bits became 0, and I needed to replace it. Luckily, I have another RLV12 and I thought I could make a copy of the ROM.

    I donít have a programmer which supports bipolar PROM writing. A ROM programmer with bipolar PROM support is expensive, and I tried to use TL866II Plus. But, TL866 doesnít support bipolar PROM. So, I tried to use an EEPROM instead of obsolete 82S181.

    I made adaptor PCBs to use cheap TL866 ROM programmer to copy the content from obsolete 82S181 to AT28HC64B-70SU EEPROM.

    Step 1: Reading 82S181
    I made the DIP24-DIP28 adaptor PCB to read 82S181, pretending AT28HC64B-70SU. The circuit diagram is in PROM2READER.pdf. The "Pin Detect" option should be unchecked because some pins are not connected, causing errors. The first 1024 bytes are idetical to the original 82S181.

    Step 2: Programming EEPROM
    It is very simple. I wrote AT28HC64B-70SU with the normal SOIC28-DIP28 adaptor.

    Step 3: EEPROM adaptor for DIP24
    I made the SOIC28-DIP24 adaptor to pretend 82S181. The circuit diagram is in EEPROM2RLV12.pdf

    Then, my RLV12 came back!

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  2. #2
    Join Date
    Mar 2008
    Westchester County, NY


    Most excellent! I had to resort to something like that a few years back to fix one of my DSD440s. My work is a little more crude, but it still works: . I have two DSD440s, and so I too made an adapter for my usual eprom programmer to read the fuse wire rom out from the good drive.



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