Apple IIe and IIc A2M2012 Joystick (Self Centring)
The Apple II Joystick is an analogue input peripheral
primarily used for playing games.
The joystick connects to the computer using a DE-9 connector and
while there is a green wire present in the lead it is not used.
Interestingly the joystick packaging states that it can be connected
to an Apple II computer however this was only possible with an adapter.
Apple stopped making the adapters, however they could still be purchased
from Southern California Research Group who also made adapters that
allowed two joysticks to be connected to an Apple II+ and an Apple IIGS.
Analogue joysticks use a
continuous current through two potentiometers (pot(s)) that varies as the
user moves the stick. This allows for gradual increases in movement VS
digital joysticks having usually only four on / off contacts for up,
down, left and right; combinations of the four create diagonal input.
Modern gaming thumb sticks are analogue VS the D-Pad which is digital.
The joystick was intended to be self centring meaning that if you
released the stick it would find a middle location through the use of
loaded springs and movement output would stop. Non-self centring
joysticks just flop about. This centre is the dead spot where the
software and computer hardware accepted that this level of current from
each pot meant the joystick was in the middle so no action(s) should be
In reality however this centre could be slightly
off and so there were two controls on the bottom of the joystick to
allow the user to set the centre.