Editing Computer mouse (section)

=== Early mice ===
[[File:Computer Museum of America (02).jpg|thumb|Xerox Alto mouse]]
In the 1970s, the [[Xerox Alto]] mouse, and in the 1980s the Xerox [[optical mouse]], used a [[rotary encoder#Incremental rotary encoder|quadrature-encoded]] X and Y interface. This two-bit encoding per dimension had the property that only one bit of the two would change at a time, like a [[Gray code]] or [[Johnson counter]], so that the transitions would not be misinterpreted when asynchronously sampled.<ref name="Lyon_1981" /> The 1985 [[Sun-3]] workstations would ship with a ball based, bus mouse, connected via an 3 pin mini din socket. Sun later replacing the ball for an optical mechanism dependent on a patterned, reflective, metallic mouse mat, with their type M4 mouse.<ref>{{Cite web |title=Sun M4 Optical Mouse |url=https://www.computerhistory.org/collections/catalog/102689966 |website=Computer History Museum}}</ref>

The earliest mass-market mice, such as the [[Apple mouse#Models|original Macintosh]], [[Amiga]], and [[Atari ST]] mice used a [[D-subminiature]] 9-pin connector to send the quadrature-encoded X and Y axis signals directly, plus one pin per mouse button. The mouse was a simple optomechanical device, and the decoding circuitry was all in the main computer. The 1987 [[Acorn Archimedes]] line kept the quadrature-encoded mice of the 68000 computers, and the aftermarket mice sold for 8-bit home computers, like the [[AMX Mouse]], but opted for its own propriety 9 pin mini din connector.<ref>{{Cite web |title=SmallyMouse |url=https://www.domesday86.com/?page_id=245 |access-date=2025-04-18 |website=Domesday86.com |language=en-GB}}</ref>