If Port Is Used As Mouse/Trackball
Pin  Mnemonic   Description
 1   V          Vertical pulses
 2   H          Horizontal pulses
 3   VQ         Vertical quadrature pulses
 4   HQ         Horizontal quadrature pulses
 5   UBUT*      Unused mouse button (middle)
 6   LBUT*      Left button
 7   +5V        +5V, current limited
 8   Ground
 9   RBUT*      Right mouse button
If Port Is Used As Joystick
Pin  Mnemonic   Description
 1   FORWARD*   Forward joystick switch
 2   BACK*      Back joystick switch
 3   LEFT*      Left joystick switch
 4   RIGHT*     Right joystick switch
 5   Unused
 6   FIRE*      Left mouse button
 7   +5V        125ma max, 200ma surge
 8   Ground
 9   Unused