The Z86319 is a member of the Z8 family of CMOS microcontrollers architecture to be used in mouse applications. These devices offer on-board pull-up and pull-down resistors, a trip-point buffer to accommodate opto-transistor outputs, and high drive ports capable of up to 10 mA current sinking per pin (3 pins maximum). A permanently enabled Watch-Dog Timer ensures operational reliability across a broad range of mouse application environments. The precision RC oscillator filters out highfrequency noise from the oscillator input pin. When configured as inputs, P24-P27 have built in voltage dividers (25K pull-up /7.5K pull-down). The input levels are designed for connection to the emitters of the opto-transistors and switch at a voltage level of 0.4 VDD.