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GALs and old PCBs

Discussion in 'Electronic Basics' started by matt, Feb 21, 2006.

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  1. I'm really puzzled. Had a look at the schematics. The device is supposed to
    do straight forward address decoding. No latches, no tricks no reason to
    think the GAL to be too fast. Had a look at the JEDEC as well. Did not check
    it out up to the last bit but as far as I can see it is programmed to do
    what the GAL guy said. What's more, a correctly programmed GAL should be
    pin-compatible with the original 82S153. There's only one nasty possibillity
    I can think about: there have been GALs on the market that did not meet the
    full specs due to a mask fault. The company made new masks and sold the old
    ones to another firm that used them to made there own GALs, including the
    flaw. I never had a problem myself so it's only hearsay. Besides I'm not
    sure the D-types were effected, but you may have run into this old problem.

    You can make some hardware to compare the 82S153 and the GAL16V8D. An EPP
    printerport, some LS364 latches and a LS245 buffer on a breadboard is all
    you need. Feed the DUT with a counter, read back all outputs and save the
    results on disk. Read the next device and compare the results.

    Can't you find someone with a programmer that can read the old 82S153? It's
    only combinatotial logic and FAIK they had no security bit. Somewhere I
    still should have the software to make equationfiles from the JEDEC. It's
    easier then building hardware.

    petrus bitbyter
  2. matt

    matt Guest

    I've tried three different types of GALs now (all different speeds
    too) but the results are the same. So presumably that means I don't
    have a faulty one - or do you mean that the guy who came up with the
    original JEDEC was maybe using a faulty GAL?
    I wouldn't know where to start there I'm afraid - not without a
    schematic (and no, that's not a hint :)
    Very true - I'll ask around.

    Thanks for your help. :)
  3. matt

    matt Guest

    To follow-up on this - firstly I haven't made up that 'slowdown'
    circuit yet, as I've finally managed to contact the guy who came up
    with the JEDEC and it transpires that he used a 10ns GAL, so I guess
    my 25ns may be too slow? :)

    I've also tried 7ns and 15ns GALs but to no avail.

    Perhaps I need to get hold of and try a 10ns GAL?

    BTW, is there a JEDEC editor for Windows that a GAL 'dunce' like me
    could use?
  4. Guest

    Maybe your board isn't actually the same as his. There might have been
    some minor change.

    Maybe you could send the other guy one of your surplus of programmed
    GALs and ask him to test it, or even reprogram it for you?

    Since you have the working chip, this really would be a good time to
    build yourself a truth table extractor using a parallel port - perhaps
    even use one of your extra GALs as an I/O expander. Good project,
    you'll learn a lot, and likely find a way in which the file you
    programmed your GAL with does not duplicate the functionality of the
  5. matt

    matt Guest

    That's possible, but I'm not aware of any changes made to this
    particular PCB (Robby Roto was never a popular arcade game).
    Hmmm, yes - good idea.
    To be honest I wouldn't know where to start - although some schematics
    would help. Do any exist on the 'net - a quick search doesn't turn up
  6. Guest

    I doubt the board is unique to Robby Roto. It's probably used in a
    whole range of games from that maker. More interesting question is if
    they made all the Robby Roto's at once, or if a Robby Roto consist of
    Assy-547, Assy-628, Assy-71 (with rom #521) etc... and could be put
    together from these more generic stock components at any time over
    several years. You might also have a replacement for a failed original
    memory board?
    Read up on parallel port interfacing. Start by learning to turn some
    LED's on and off under software control. Learn to read the state of
    the status inputs. You may not have enough bits for all the inputs and
    outputs, in which case you have the option of using a switch for the
    unused input and manually changing it partway through the run. You can
    also change the inputs back to the computer - maybe only read half the
    chip outputs at a time. Or you can program one of your GALs to
    multiplex the signals, but that's a more involved project.

    By the way, this is easier with a windows 98 (or dos) or earlier PC,
    though there are dirvers such as giveio which will let you program the
    parallel port in windows XP.
  7. matt

    matt Guest

    In this case it is as Robby Roto and a few others all shared four of
    the stacked boards, while there were two other boards in the rack that
    are unique to each game. In this case it's the Memory Board that I'm
    having problems with which is unique to Robby Roto. :)
    It's definitely an original - matches the schems, serial nos, etc.
    Sounds simple. ;)
    Thanks - yes, I'm on XP Pro.
  8. Sambo

    Sambo Guest

    Hmm, was wondering if the ram or rom wasn't different speed.

    If the other person used 10ns chips and it worked, then 7 or 15ns should be close enough for a 1.8Mhz design.
    Sounds like logic check is in order. What programmer are you using.
    Why can't the programmer be used to read the truth table, unless it is something hobby grade as the galblast I found on the net.

  9. Checked out the JEDEC and the schematic as far as I can and found no
    contradictions. The memory map looks like:

    0000-3FFF X1-X4
    8000-BFFF X5-X8
    C000-CFFF X9-X10
    E800-FFFF X22-X24 Write
    E000-FFFF X21-X24 Read

    Apparently X21 will not be written, that is to say, not by using this
    address decoder.

    The more I see about it, the more I get the feeling your GAL is not
    correctly programmed. Do you have any possibillity to read back your GAL by
    another programmer and check whether the JEDEC is read back correctly? If
    not, the best you can do is building the hardware I mentioned before. But,
    drawing a schematic is no big problem. Not to me. But... then it has to be
    build and hooked up to a PC. I would fire up an old DOS machine and write a
    quick and dirty GWBASIC or maybe TURBOC program to read the components.
    That's a lot of work, guess at least a full day. So if you want the
    schematic, just say it.

    BTW to learn about parallel port programming (and many other things) look at

    For your application I like to use the EPP-port best.

    petrus bitbyter
  10. matt

    matt Guest

    All the 6116's on the board are HM6116LP-4
    A Galep-4 .....
    Read it from the original 82S153 you mean? If so, afraid it can't
    handle that device. :(

  11. matt

    matt Guest

    Almost - it's C000-DFFF for X9-X10 - a fault in the JEDEC perhaps?
    The 6116 at location X21 is battery backed and used to store high
    scores, game settings, etc.
    Afraid not, no. :(

    However, it verifies okay with the existing programmer - a Galep-4,
    details here on that programmer:
    Thanks for the kind offer - I don't though want to put you to any
    unnecessary trouble so let's see how it goes as to alternative
    Many thanks. :)

  12. C000-CFFF X9-X10 must be C000-DFFF X9-X10
    no JEDEC fault, a petrus typo.

    The conitec site seems to have problems at the moment. But FAIK the Galep is
    a decent programmer. Guess you kept your software up to date. I'm out of
    ideas for the moment :(

    petrus bitbyter
  13. matt

    matt Guest

    Hmmm, I can access the site okay.

    Yes, the Galep is a decent programmer so I would have thought it would
    be okay.

    Here's a thought - if I was to get the 82S153 dumped, what would be
    involved in turning it into a JEDEC?
  14. Sambo

    Sambo Guest

    hmm. the one I have been dreaming about for 2 or 3 years. Over time I guess I transposed verifying devices to reading any device truth table.
    Perhaps this is a good time to fire a message to them to provide a program that
    can be configures for input/output pins and reading truth tables and then I'll purchase it.
  15. matt

    matt Guest

    Would that be relatively easy to code?
  16. Sambo

    Sambo Guest

    With their "UNIVERSAL PIN DRIVER TECHNOLOGY" should be a piece of cake.
    This could be also used for testing regular logic ICs.
  17. Sambo

    Sambo Guest

    With their "UNIVERSAL PIN DRIVER TECHNOLOGY" should be a piece of cake.
    This could be also used for testing regular logic ICs.

    I have read some time ago about one of those new programmable chips ( little more analog than the rest ) and said to myself "this would be perfect for the heart of a programmer".
    If one of those is the heart of Galep....
    I emailed them asking about their plans to provide at least basic program that configures power , input and output pins and sends test pattern and reads the outputs, will see what they say. I have seen other programmers in the past, claming to be able to test TTLs and even RAMs.

  18. matt

    matt Guest

    Any reply yet? :)
  19. Sambo

    Sambo Guest

    Not a peep and I just realized that it is another product that suffers from devolution.
    6 AAA? That does not sound like more power than 2x9V which should be about the same
    space if not less. I know there are cons to putting batteries in parallel but nothing a WARNING and double pole switch couldn't fix
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