Editing Atari interface (section)

===Atari ST and Amiga===
Mice for both the [[Commodore Amiga|Amiga]] and [[Atari ST]] are [[Bus mouse|Bus mice]] which produce quadrature signals and buttons to different pins.
Some third-party mice have support for both systems, selected via a switch that only changes which pins the quadrature signals go to.
The left mouse button is wired the same as a joystick's Fire button and the other button(s)s also short to ground.

On the Amiga, signals are interpreted by circuitry in its custom chipset and there is hardware support for a mouse in each port. A second Amiga mouse can be used only in some two-player games, however.
On the Atari, one mouse can be plugged into a dedicated mouse/joystick port on the keyboard, which is interpreted by the keyboard's microcontroller. A curious detail is that the Atari ST's right mouse-button is wired to and read as the other port's Fire button.

Amigas typically have two-button mice. Commodore made a three-button mouse only for the Amiga 3000UX that ran Amiga [[UNIX]] but many third-party Amiga mice also came with middle-button.
In the late 1990s, there appeared third-party Amiga mice with [[scroll wheel]]s, using varying current on the POTX line (pin 5) for input which required a special driver. The third button is represented in a new way.<ref name="micromysv3">Micromys.de—[http://micromys.de/Amiga_devel.htm Micromys support page - Amiga mouse mode with wheel support]. Dated 2000. Retrieved 2019-03-24</ref>

The Amiga's operating system provides (when booted into Workbench) also [[mouse keys]] as combinations together with the [[Amiga key]]s.