Z08617 NMOS Z8
®
8-B
IT
MCU
K
EYBOARD
C
ONTROLLER
6
PIN FUNCTIONS
RCIN
This pin is connected between a precision resistor
on the power supply from the precision RC Oscillator.
CLK Out
This pin is the syste m clock of the Z8 and
runs at the frequency of the RC Oscillator. Any load on
this pin will effect the RC Oscillator frequency.
Port 0
(P07-P00). Port 0 is an 8-bit, nibble program-
mable, bi-directional, NMOS compatible I/O port. These
eight I/O lines can be configured under software
control as a nibble input port, or as a nibble open-drain
output port. When used as an I/O port, inputs are
standard NMOS (Figure 5). Port P03-P00 has 10.4
Kohms (
±
35%) pull-up resistors when configured as
inputs.
Figure 5. Port 0 Configuration
Port 0
I/O
(Open-Drain Output)
Z8615
4
4
Input
Output
Pad
OEN
10.4 Kohms
(a) Port P00-P03
Input
Output
Pad
OEN
(b) Port P04-P07
