This M-2 mouse was marketed by Mouse Systems as PC Mouse. The original pearl white has aged to computer greige with tan/grey buttons. M-2 PC Mouse came bundled with Pop-up menu software. As an improvement on the M-1, this mouse does not require callibration every time it is turned on.
Its rectangular interface block has a triangular projection for the fixed cord to the mouse, beside a port for the jack of the power supply. It connects to the computer's serial port. On the mouse bottom, the two oblong holes for the LEDs are parallel, not slanted as on the M-1 model.
The MOUSE SYSTEMS brand on the back is accompanied by a holey cheese wedge icon, as does the A+ Mouse for the Apple IIc.
A 7 3/4" x 9" gridded metal desk pad came with the M2 121043. It is number 400207-003-REV. 3.
Mouse Systems M-2 PC Mouse on its desk pad.
Mouse Systems M-2 mouse with the the MOUSE SYSTEMS brand on the front. (This one is SN: M2 121576.)
Mouse Systems marketed an M-2 mouse with a DB-25 hole plug with only its MOUSE SYSTEMS name on the front. The corporation also made an OEM Model M-2 optical mouse, which had only two square buttons, for PCjr IBM computers.
Connecting the mouse to the PCjr computer from PCjr Mouse Setup Guide by Mouse Systems 1985.
The proprietary PCjr Mouse cable splits off into the serial plug that plugs into the computer and the little square plug that connects into the light pen port, labeled LP, at the rear of the PCjr computer. This provides power for the mouse. Like the A+ Mouse, this one needs no external power supply.