ZiLOG Z08617 Manual page 9

PIN FUNCTIONS (Continued)
Port 3 (P37-P30). Port 3 is an 8-bit, NMOS compatible four-
fixed-input and four-fixed-output I/O port. These eight I/O
lines have four-fixed-input (P33-P30) and four-fixed-out-
put (P37-P34) ports. Port 3 inputs have 10.4 Kohms (± 35%)
pull-up resistors and port 3 outputs are capable of driving
up to four LEDs.
Port 3 is configured under software control to provide
the following control functions: four external interrupt
request signals (IRQ3-IRQ0); timer input and output
Z8615
Output
(a) Port 3 P34-P37
Input
(b) Port 3 P30-P33
Figure 8. Port 3 Configuration
signals (T and T - Figure 8).
IN OUT
/RESET (input, active Low). When activated, /RESET
initializes the Z08617. When /RESET is deactivated,
program execution begins from the internal program
location at 000CH. Reset pin has a 10.4 Kohms pull-
up resistor. Once this pin is pulled Low, it takes about
150 ms for microcon-troller initialization.
Port 3
(I/O or
Control)
Pad
10.4 Kohms
Pad
®
Z08617 NMOS Z8 8-B MCU
IT
K C
EYBOARD ONTROLLER
9