W78e065a40pl plcc

Discussion in 'General Electronics Chat' started by Jotto, Apr 27, 2011.

  1. Jotto

    Thread Starter Member

    Apr 1, 2011
    Does anyone have experience with this type of chip? After reading the data sheet on the component, there is a lock that can be enabled to protect the program. If you do a check sum on this, if its locked will it still be able to determine the correct check sum?

    I have the ability to program or read this chip if the lock isn't enabled. Is there a back door to access the program?

    This component is used in a LCD unit, after spending part of the day troubleshooting it down to a few components that could be the problem, I determined that its the processor that is bad. Talking with the manufacture on this A/D board, they said it was a common fault on this model. Problem is that they don't sell the part only the complete board. If I can extract the code I can program a new one.

    EA - EXTERNAL ACCESS ENABLE: This pin forces the processor to execute out of
    external ROM. It should be kept high to access internal ROM. The ROM address and
    data will not be presented on the bus if EA pin is high and the program counter is within on-chip ROM area.

    7.1 Lock Bit
    This bit is used to protect the customer's program code in the W78E51B. It may be set after the
    programmer finishes the programming and verifies sequence. Once this bit is set to logic 0, both the
    on-chip ROM data and Special Setting Registers can not be accessed again.

    My thought was if I can force EA to change states, will it allow access to the complete program? Any thoughts or insights would be greatly appreciated.

    Thanks Jim

    Chip is locked, waiting on engineering from Wells Gardner to see if they will provide the firmware. Have a feeling they won't because of proprietary information regarding their programming.
    Last edited: Apr 27, 2011