Z86319 Datasheet, PDF (8/23 Pages) Zilog, Inc. – PS/2 MOUSE CONTROLLER

Z86319
PS/2 Mouse Controller
PIN FUNCTIONS
Port 0 (P02-P00). Port 0 is a 3-bit, I/O programmable, bi-
directional, CMOS-compatible I/O port. These three I/O
lines can be configured under software control to be input
or output (Figure6). When Port 0 is configured as an input
port, all lines have the capability to either sink or source
(ROM mask selectable) current emulating a 100K pull-
Zilog
down or pull-up resistor. Port 00-02 can be accessed
through the P0 register (register address 00). The upper 5
bits of this 8-bit register always reads “11111.” Writing to
the upper 5 bits has no effect (see Figure 34). The lower 3
bits of the P0 register are read/write. Current versus pin
voltage graphs are shown in Figures 7 and 8.
Pull-Up Enable
(Mask Option)
OE
Out
In
Pull-Down / Enable
(Mask Option)
Figure 6. Port 0 Configuration
Pad
8
PRELIMINARY
DS97KEY1605