== I/O ports ==
Port &F990 : 0321RLDU : Input = Port A, joystick and buttonsActions bits
Port &F991 : 0321RLDU : Input = Port B, joystick and buttonsActions bits
Port &F992 : 0000XXXX : Input = Port A, mouse Mouse POS-Xvalue
Port &F993 : 0000YYYY : Input = Port A, mouse Mouse POS-Yvalue
Port &F994 : 0000XXXX : Input = Port B, mouse Mouse POS-Xvalue
Port &F995 : 0000YYYY : Input = Port B, mouse Mouse POS-Yvalue
Ports &F996 and &F997 are unused. === Action bits === bit0: Up bit1: Down bit2: Left bit3: Right bit4: 1st fire or LMB bit5: 2nd fire or RMB bit6: 3rd fire or MMB bit7: 0 === Mouse bits === bit0-2: value bit3-7: sign (all 0 or 1)
