Indivision AGA MK3 change in joystick behaviour

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Don't Panic. Please wash hands.
  • Hi!


    I have installed the Indivision AGA MK3, great piece of kit and love the live configuration feature! However when testing using one of my favourite games, Battle Squadron, I noticed that the fire button on the joystick behaves differently. It has now gained "auto fire" which is great, but it has also deprived me of the possibility to use a Mega Bomb. To use a Mega Bomb, the fire button needs to be kept pressed down and the stick needs to be rotated full circle.


    With the CIA adapter removed, the behaviour is back to normal. Ergo, the Indivision CIA adapter does something to the FIRE signal of the joystick. Specifically it seems to make the FIRE signal intermittent instead of constant.


    How to solve this?!


    Thanks for reading!

  • With the CIA adapter removed, the behaviour is back to normal. Ergo, the Indivision CIA adapter does something to the FIRE signal of the joystick. Specifically it seems to make the FIRE signal intermittent instead of constant.

    That's interesting - especially because we don't even touch the joystick "fire" signal. Only the mouse button "fire" signal (which is the left mouse button) is handed over to the hardware of the flicker fixer.


    The only explanation I have for this is that the keyboard "sniffer" is causing this. In order to catch key presses without the OS running (which is the case for most games and demos), the "acknowledge" signal is sent by the flicker fixer instead of the CPU. This *may* happen, resulting in Battle Squadron believing that the joystick button has been released, where in fact it has been pressed all the time.


    Maybe we can implement a temporary "disable" for the keyboard sniffer. I'll talk to Peter.

  • The only explanation I have for this is that the keyboard "sniffer" is causing this. In order to catch key presses without the OS running (which is the case for most games and demos), the "acknowledge" signal is sent by the flicker fixer instead of the CPU. This *may* happen, resulting in Battle Squadron believing that the joystick button has been released, where in fact it has been pressed all the time.


    Maybe we can implement a temporary "disable" for the keyboard sniffer. I'll talk to Peter.

    No current core doesn't send an keyboard ack itself. So that is not it.

  • OK, and the internally-proposed "short between other pins" is improbable either, as we do both a visual and a functional inspection of each component.


    So the best explanation we currently have is that the auto fire function of the joystick in question was accidentally switched on/off, which coincided with the time that the CIA adapter was put on/off.

  • This is getting more mysterious - Peter confirms that we are not sending any ACK to the keyboard, so we do really *nothing* in terms of active signals that go back to the CIA chip.


    I'll have to try that out here - I should have the game somewhere in the huge pile of floppies that I acquired over the years. Will dig over the weekend and measure a few things with the logic analyzer next week.

  • OK, and the internally-proposed "short between other pins" is improbable either, as we do both a visual and a functional inspection of each component.


    So the best explanation we currently have is that the auto fire function of the joystick in question was accidentally switched on/off, which coincided with the time that the CIA adapter was put on/off.

    There's no short indeed. Considering that the Competition Pro joystick does not have an auto-fire feature, it can't have been switched on or off.