Tandy TRS-80 Deluxe Joystick (Self Centring)
The Tandy TRS-80 Joystick is a single fire/action
button, analogue input
peripheral primarily used for playing games on the Tandy Color Computer
and Colour Computer 2.
The joystick connects to the computer using a round, five pin connector.
The version designed for the Tandy Color Computer 3 has six pins to
accomodate a second (black) fire/action button. As the joystick socket
on the Color Computers 1 and 2 were the same as the 3 the dual button
version could be used on all three models with the second fire button
only functioning on the third.
Analogue joysticks use a
continuous current through two potentiometers (pot) 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.