To display a row of characters in the VGA alphanumeric mode, the ASCII and attribute bits for all such characters are retrieved from the main memory and stored in a local cache memory. A gouged section 151 is formed on the side frame 141, A rear connecting member 113 ties the two rail members together near the rear sensors, and another connecting member 5, which has a width that is wider at either end than it is in the center, ties the two rail members together forward for the rear load sensors. Of these signal lines, a 5-V power supply line for supplying 5-V power to the SIE 2 is provided with a switch 3 for electrically on-off switching it. The spherical bearing may be dry or may be lubricated with a liquid or with pressurized air to minimize the bearing friction and enable the transducer to self-align. When the light emitting module is connected to a power supply of a computer by the control module, the control module detects intensity of ambient light around the computer mouse and controls the light emitting module to turn onoff according to the detected ambient light intensity.