Any way to switch between two ICs?

Discussion in 'General Electronics Chat' started by grimholtz, Oct 31, 2010.

  1. grimholtz

    Thread Starter New Member

    Oct 29, 2010
    4
    0
    Hi,

    I have two 24-pin integrated circuits. Right now, the circuit into which they plug accepts only one of them. They can be swapped manually to change the behavior of the circuit.

    I'd like to be able to switch between them without having to physically swap the ICs. Is this possible? I realize the power to the circuit should be off when I do this.

    Is there any way to switch between two 24-pin ICs? I can't find a 24-pole double-throw switch anywhere :)

    thanks,
    grimholtz
     
  2. beenthere

    Retired Moderator

    Apr 20, 2004
    15,815
    282
    Is there a chip select line used with these IC"s? If so, that should do the trick. Of course, that depends on the unnamed IC's. Their data sheets will say if that is the case.
     
  3. grimholtz

    Thread Starter New Member

    Oct 29, 2010
    4
    0
    I'll repost when I have the IC numbers. In the meantime, if there's no select line, is there an alternative?
     
  4. Kermit2

    AAC Fanatic!

    Feb 5, 2010
    3,795
    951
    buffering the inputs and outputs with a bus driver with a chip select?

    Have you looked into switches that come in the older data selector boxes, they used to be used to switch printer ports between two printers and one computer. Ganged rotary switches with 25 switches on a single shaft.
     
  5. SgtWookie

    Expert

    Jul 17, 2007
    22,182
    1,728
    It will be difficult to say without knowing what the ICs are.

    If the socket is not a ZIF-type, you will sooner or later start breaking off the pins of the ICs.
     
  6. grimholtz

    Thread Starter New Member

    Oct 29, 2010
    4
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    Excellent idea. I hadn't thought of that. By the way, they do fit a socket.
     
  7. SgtWookie

    Expert

    Jul 17, 2007
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    You haven't said what kind of ICs you're dealing with yet.

    If they are analog, adding lengths of wiring will likely increase the noise on the pins.
    If they are digital, you may wind up with excessive ringing.
     
  8. grimholtz

    Thread Starter New Member

    Oct 29, 2010
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    0
    Sorry, I don't have the IC numbers in front of me. I will look them up shortly. For what it's worth, they are ICs from a circa 1982 Ms. Pac-Man arcade game (not a console video game, but the actual arcade machine). One IC makes Ms. Pac-Man move fast while the other makes her move "normal" speed. I want to switch between the two without having to swap ICs every time.

    grimholtz
     
  9. thatoneguy

    AAC Fanatic!

    Feb 19, 2009
    6,357
    718
    Sounds like they are simply PROMs (Programmable Read Only Memory).

    They should have a chip select line on them, the problem then becomes making a board to hold both ROMs, and integrating it into the arcade machine.
     
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