Editing Atari interface (section)

==Digital joysticks and gamepads==
[[File:Tac-2.jpg|200px|thumb|right|The '''Suncom TAC-2''' (''Totally Accurate Controller mk 2'') is still popular with retro gamers]]
Different systems have implemented the standard, sometimes with different extensions for more buttons or other capabilities.

The [[Joystick#Digital|joysticks]] have eight directions and one button, often named "Fire" or "Trigger".
The directions up, down, left and right have individual pins, with diagonals as combinations of up+left, up+right, down+left and down+right respectively.

===Atari joysticks===
[[Atari]]'s joystick standard was introduced with the ''Atari VCS'' (''Atari 2600'' after 1982) and was then used on Atari 8-bit computers (''400'', [[Atari 800|800]], ''1200'', ''XL'', ''XE'') and the [[Atari ST]] line (including ''TT'' and ''Falcon'').
Most games consoles and home computers had two ports but the Atari 400 and [[Atari 800|800]] had four.

Many third-party joysticks for this pinout do have more than one button, but only for convenience — they are all wired to the same line.
Joysticks with [[Autofire|repeat-fire]] were supposed to use the +5V line for power but some are instead powered by the host's pull-up current on the button's pin.<ref name="jakadapterpullup">[http://kair.us/projects/jakadapter/index.html Jakadapter]. Section "Hardware", third paragraph. Dated 2018-10-20. Retrieved 2018-12-02</ref>

Atari released a ''Booster grip'' accessory for the 2600 with a passthrough for the joystick. It added a thumb button and a trigger; each on a POT line, shorting it to +5V when pressed and thus read as a [[#Paddles|paddle]].

The Atari 7800 console has joysticks with two trigger buttons but the console is backwards-compatible, containing also Atari 2600 hardware. Each new trigger button is wired between the 2600's trigger pin ''and'' a POT line with pull-down resistors to ground. This setup means that the buttons are two different buttons in 7800 mode but have the same function in Atari 2600 mode.
<ref name="atariage7800">AtariAge [http://atariage.com/7800/faq/index.html?SystemID=7800#cat2_9 7800 FAQ]. Retrieved 2017-03-30.</ref>

===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>

===ZX Spectrum===
The original Sinclair ZX Spectrum did not originally come with a joystick port so most games used the keyboard. The standard was to use 5-8 on the numeric row as [[cursor keys]].

A two-port expansion card called ''ZX Interface 2'' was released by Sinclair but not before the single-port ''Kempston Joystick Interface'' expansion card from ''Kempston Micro Electronics'' had established itself on the market.
The ZX Interface 2 mapped joysticks to keyboard keys on the numeric row — but to different keys than the cursor standard.
Other cards exist that map to either, to both or to both ''and'' the older keyboard standard.

The ZX Interface 2 does not connect the +5V line, so joysticks with turbo/auto-fire do not work. <ref name="fruitcake">Sinclair ZX Resource Centre —  [http://www.fruitcake.plus.com/Sinclair/Interface2/Interface/Interface2_Introduction.htm ZX Interface 2]. Retrieved 2018-05-24</ref>
The Kempston does not only connect the +5V line, it also allows lines 9 and 5 to be read as buttons.<ref name="yarekkempston">8bit Projects for Everyone—[https://8bit.yarek.pl/hardware/zx.joystick/index-de.html Kempston Joystick]. Dated 2002-10-12. Retrieved 2018-05-24</ref>

The Spectrum +2 and later (the [[Amstrad]] era) did come with 2 DE-9 joystick ports that were used like the ZX Interface 2's ports by programs — but the pinout is different from the Atari standard.

===SAM Coupé===
The SAM Coupé 8-bit computer has a single joystick port that connects one Atari-compatible joystick, or two with an adaptor.

Both inputs and the strobe lines are shared with the [[keyboard matrix]], with each joystick's inputs producing keycodes that already exist on the keyboard.
Each common line on the connector strobes each joystick in turn.
An adaptor would need diodes to avoid joysticks from clashing. Because the hardware is "temperamental", it is recommended to use germanium diodes with a low voltage drop, or to use a tristate buffer for each joystick. <ref name="worldofsam">WorldOfSam.org—[https://www.worldofsam.org/products/keyboard-and-joystick-port Keyboard and Joystick port]. Dated 2018-05-16. Retrieved 2019-10-05</ref>.

===Multi-port adaptors===
Numerous adaptors have been made from digital joysticks and gamepads to [[Parallel port|DB-25 parallel ports]].
A typical adaptor or ''Multi Joystick Extender'' connects two (additional) joysticks.
This did require specific software support in multiplayer games for the Amiga and Atari ST.<ref name="amigamje">[http://old.pinouts.ru/InputCables/Amiga4Joysticks_pinout.shtml Amiga 4 joysticks adapter pinout]. Retrieved 2014-10-04</ref>

A ''MultiJoy'' adaptor for the Atari 8-bit computers can connect up to 16 (or more often 8) joysticks on the original joystick ports. Older games that supported three or four players only on the first generation of Atari 8-bit machines have been modified to work with these.
A demultiplexer chip is used to select which joystick's ground line to strobe. The joystick number is output on port 2's direction lines and the selected joystick is read on port 1.
<ref name="multijoy8">Atari 8bit.net—[https://atari8bit.net/multijoy8/ Multijoy8]. Retrieved 2020-04-23</ref>