The Z86317 is a member of the Z8 family of CMOS microcontrollers architected to be used in mouse applications. These devices offer on-board pull-up and pull-down resistors, a scalable trip-point buffer to accommodate opto-transistor outputs, and high drive ports capable of up to 10 mA current sinking per pin (six 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 are configured as voltage divider (25K pull-up / 7.5K pull-down). The input levels are adjusted for connection to the emitters of the opto-transistors and switch at a voltage level of 0.4 VDD. For applications requiring powerful I/O capabilities, the Z86317 provides dedicated input and output lines that are grouped into three ports. There are two basic address spaces available to support this configuration: Program Memory, and 124 bytes of general-purpose registers.