67
CHAPTER 5 PERIPHERAL HARDWARE FUNCTIONS
CHAPTER 5 PERIPHERAL HARDWARE FUNCTIONS
5.1 DIGITAL I/O PORTS
The µPD750008 employs the memory mapped I/O method. Thus, all input/output ports are mapped on
the data memory space.
Figure 5-1. Data Memory Addresses of Digital Ports
Remark Some I/O parts can be used as static RAM.
Input/output port manipulation instructions are as listed in Table 5-2. Ports 4 to 7 can be manipulated not
only in 4-bit units, but also in 8-bit or 1-bit units so that these ports can be controlled in various ways.
Example 1. To test the condition of P13 and output different values to ports 4 and 5 according to the test
result:
SKT PORT1. 3 ; Skips if bit 3 of port 1 is 1
MOV XA, #18H ; XA <– 18H String-effect instructions
MOV XA, #14H ; XA <– 14H
SEL MB15 ; Or CLR1 MBE
OUT PORT4, XA ; Port 5, 4 <– XA
2. SET1 PORT4. @L; Sets the bit(s) specified by the L register, in ports 4 to 7, to 1.
P03 P02 P01 P00
P13 P12 P11 P10
P23 P22 P21 P20
P33 P32 P31 P30
P43 P42 P41 P40
P53 P52 P51 P50
P63 P62 P61 P60
P81 P80
PORT 0
PORT 1
PORT 2
PORT 3
PORT 4
PORT 5
PORT 6
PORT 8
FF0H
FF1H
FF2H
FF3H
FF4H
FF5H
FF6H
FF8H
Address 3210
FF7H P73 P72 P71 P70 PORT 7
5