By midyear 1987, Microsoft had shipped more than half a million mouses, selling 50,000 a month. The nicknamed little "Dove bar" mouse featured plug-compatiblility with serial or bus cards. Microsoft called one of them the Serial - PS/2 Compatible Mouse and the other, the bus mouse, the InPort™ Mouse. The InPort mouse converted to serial with a block adapter that Microsoft calls Mouse Interface. The block came in a long cube or rectangular shape with a bus port on each end to accomodate the D-ring plug.
The Serial - PS/2 Compatible Mouse version converted to PS/2 with a plug adapter with only 4 pins of the DE-9 configuration that plugs into the mouse's DE-9 hole plug, switching it to a PS/2 pin connecter on the other end of the cable. It's not clear if the InPort bus mouse could further adapt to PS/2 after it was plugged into an adapter to serial. Maybe there's another special adapter for that which didn't make it to the collection.
Microsoft advertised in 1988 that the Microsoft Muse was available in serial-PS/2®, InPort™, and bus versions. Only the first two are shown here. In 1991 it was advertising the same shaped mouse as the contour Microsoft mouse. And a year later it boasted "400-points-per-inch tracking."
The Microsoft "Dove bar" bus mouse enables plug-compatiblility by use of either a long cubed or block shaped connector with D-ring ports on each end to adapt the D-ring bus plug to a serial or PS2 port, but there's some question how the latter is attained. The serial plugs are DE-9. The cord is very long.
The two buttons on the little mouse form the front of the body fitting flush rather than protruding as in the earlier mouse buttons. The mouse is nearly 4" long but a narrow 2-1/8" wide. These mice are common in thrift stores because they enjoyed such a long run.
Microsoft Mouse InPort Mouse with its Microsoft Mouse Interface for Serial and IBM PS/2 Mouse Ports. The bus mouse attaches to the cube to adapt it to a DB-25 hole serial plug. Each end of the cube takes a D-ring plug.
Cube style Microsoft Mouse Interface for Serial and IBM PS/2 Mouse Ports