Editing Atari interface (section)

===Commodore joysticks===
The [[Commodore VIC-20]] has one "Control port". The [[Commodore 64]]  and ''128'' have two.
All support Atari-standard joysticks and could technically also support the additional buttons on the "Booster Grip".

The Commodore 64/128 use the same I/O ports for joysticks as for the [[keyboard matrix]], but not having them part of it. Therefore, most single-player games support a joystick only in port 2, so that joystick and keyboard would not interfere with one-another.
Many games use the [[Space bar]] for additional input and strobing only for that key. Port 1's button is wired to the Space bar's column which means that pressing the button on a joystick in that port does in these games effectively press Space. Many two-button joystick mods for the C64 have taken advantage of this.

==== Power Play ====
The rare ''Commodore 64 Power Play'' Edition, sold only in Germany in 1990 came with a ''Power Pad''<ref>Retroport.de—[http://www.retroport.de/C64_Power_Play.html Commodore C64C Power Play Edition (1990)]. Retrieved 2018-06-07</ref> — a clone of a NES gamepad with two buttons.

A version of the gamepad has also been spotted with two additional buttons. On that, one of the Fire buttons was Fire, and the other Up. (Up was often used for Jump in games for Atari joysticks)

==== C64GS joystick ====
The doomed ''Commodore 64 Games System'' was essentially a [[Commodore 64]]C without a keyboard.
To compensate for the loss of keys, the joystick got a secondary fire function which shorted +5V to pin 9 (POTX), like the Thumb button on Atari's ''Booster Grip''. (Note that on the Commodore Amiga, the same pin was read as secondary fire but low instead of high.)

The bundled ''Cheetah Annihilator'' joystick had a secondary fire button but unfortunately it broke easily and a replacement that supported secondary fire was practically nonexistent.

==== Amiga ====
Every [[Commodore Amiga|Amiga]] computer has two "Controller ports" which are usually labelled "Mouse" and "Joystick" respectively.
The fire button and the mouse's left button use the same input, allowing either to work as the other when only button press is required.<ref name="elowaradcd"/>

Some Amiga-specific joysticks have a secondary Fire button, which worked like the right mouse buttons. These came about because of the popularity of using [[#Sega|Sega]] gamepads on the Amiga, where a button triggers that pin.

==== Amiga CD32 gamepad ====
The Amiga CD32 games console is based on regular Amiga hardware with two controller ports. The gamepad has a [[D-pad]] and seven buttons: Blue, Red, Yellow, Green, Right Front, Left Front and Pause. It would of course work in other Amigas given software support.

Games not specifically made for the CD32 game-pad (such as ports) would leave pin 5 high which makes Red work as Fire, and Blue as the second button.
When pin 5 is low, the button state could be read serially on pin 9 from a 74LS165N shift register using pin 6 as a clock. The register is reset by setting pin 5 high again.
<ref name="gerdkautzmanncd32">[http://gerdkautzmann.de/cd32gamepad/cd32gamepad.html CD32 Gamepad A100 re-engineered documentation]. Retrieved 2015-08-16.</ref>