[stella] Joystick buttons

Subject: [stella] Joystick buttons
From: emooney@xxxxxxxxxxxxxxxx (Erik Mooney)
Date: Tue, 01 Apr 1997 02:28:58 GMT
Re: my earlier post about problems reading the joystick.. what seems to
happen is that INPT4 and INPT5 are *supposed* to use only the highest data
bit to report trigger status.. on the emulator, the other data bits are all
returned as zero, but not necessarily on a real console.  I had been using
LDA INPT4 / BNE NoButton, which worked on the emulator but not the real
console.  Changing that to LDA INPT4 / BMI NoButton, testing only the
targetted bit, works fine. (this all is with zero in bit 6 of VBLANK, so
I'm not worrying about latching.)

Next question: exactly when does the TIA process a write to RESMPx?  My
program is a vertical shooter, so when a bullet is fired it writes 2 to
RESMP0, setting the missile to the horizontal position of the player, and
then writes 0 to RESMP0 so it can display the missile.  (this is easier to
write than doing a separate RESM0 each time a bullet is fired.)  I had no
delay between writes to RESMP0, and that works on the emulator but not the
console.. sticking a STA WSYNC inbetween writes works sometimes; usually if
the missile is more than 1/3 screenwidth away from the left side of the
screen.  Any hints here? thanks.

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