🚀 go-pugleaf

   Rich"theman"kennehan was espousing about 'Re: using atari 2600 joys',
   on [10-10-92  01:07] to All!
 Ri> Please realize that I KNOW THAT I WILL ONLY HAVE ONE BUTTON!!!  (I've
 Ri> got more than enough E-mail from people telling me what I already know!
 Ri> :) What the Adapter is going to have to do is add some resistance to
 Ri> the circuit when the joystick is pushed up or to the left (No problem)
 Ri> but is going to have to ADD some voltage when the joystick is pushed
 Ri> down or to the right.  I think I'm going to need a few transistors to
 Ri> do this.  Any suggestions?

    Let's see here you have 3 states in each direction correct?

    Left - nothing - Right

    Up - nothing - Down

    The nothing state is 50% of the total resistance.   The
    output of the Atari joystick gives you 8 states

    for convention sake let us say UP and LEFT are full
    resistance, and down and right are zero resistance or very
    low.

    Up and down generate 2 bits and left and right generate 2
    bits

    SO
    with up and down
    UD
    00 - nothing
    01 - Down
    10 - up
    11 - impossible

    with Left and Right
    LR
    00 - nothing
    01 - right
    10 - left
    11 - impossible

    I sugest using 2 4052 dual quad analog multiplexors.

    Unfortunately they don't have seperate inputs so you HAVE to
    use 2.

    here is how to use them
    LR - inputs
    ||
   +-------+
   |       +- output (to joystick port)
   +-------+
   0|1|2|3|     R1 - 100k trimpot
    R | R 5     R2 - 200k trimpot
    1 | 2 V
    +-+-+
      |
      other circuitry

    The up down part is a mere copy of this.  Up for left down
    for right.  it requires 2 chips 4 resistors.

    If I had a better diagram of the PC joystick I could give a
    better design.

            Stephen Cyberman@Toz.Buffalo.NY.US
            Scripted at Sat  10-10-1992  15:46:20

... An optimist: a person who looks for the pony in a barn full of manure.
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