Z08617 Datasheet, PDF (9/26 Pages) Zilog, Inc. – NMOS Z8 8-BIT MCU KEYBOARD CONTROLLER

Z08617 NMOS Z8^® 8-BIT MCU
KEYBOARD CONTROLLER
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
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.
Z8615
Port 3
(I/O or
Control)
Output
Pad
(a) Port 3 P34-P37
10.4 Kohms
Input
Pad
(b) Port 3 P30-P33
Figure 8. Port 3 Configuration
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