UPD17073 NEC, UPD17073 Datasheet - Page 22

• Manufacturer Part Number: UPD17073
• Description: 4-BIT SINGLE-CHIP MICROCONTROLLER WITH HARDWARE FOR DIGITAL TUNING SYSTEM
• Manufacturer: NEC

2.4 Execution Flow of Program Memory
2.5 Notes on Using Program Memory
22
Instruction
(1)
(2) With PD17073
Execution of the program is controlled by the program counter which specifies an address of the program memory.
Figure 2-4 shows the values to be set to the program counter when each instruction is executed.
Table 2-1 shows the vector addresses that are to be set to the program counter when each interrupt occurs.
CALL addr
BR @AR
CALL @AR
MOVT DBF, @AR
When interrupt is accepted
Power-ON reset, CE reset
BR addr
RET
RETSK
RETI
The program memory addresses of the
addresses that can be specified by the program counter (PC) are 0000H through 0FFFH, keep the following
points in mind when specifying a program memory address:
• Be sure to write a branch instruction to address 0BFFH, when writing an instruction to this address.
• Do not write an instruction to addresses 0C00H through 0FFFH.
• Do not branch to addresses 0C00H through 0FFFH.
The program memory addresses of the PD17073 are 0000H through 0FFFH. Keep the following point in mind:
• Be sure to write a branch instruction to address 0FFFH, when writing an instruction to this address.
PD17072
Figure 2-4. Specification by Program Counter On Execution of Each Instruction
Priority
1
2
3
Internal/external
Program counter
External
External
External
Table 2-1. Interrupt Vector Address
Page 0
Page 1
PD17072 are 0000H through 0BFFH. However, because the
b
INT pin
Basic timer 1
Serial interface
0
0
1
0
11
Interrupt source
b
0
10
b
0
9
Contents of address stack register (ASR)
Contents of program counter (PC)
Vector address of each interrupt
b
0
Contents of address register
specified by stack pointer (SP)
8
b
0
7
(Return address)
Instruction operand (addr)
Instruction operand (addr)
b
0
Vector address
6
0003H
0002H
0001H
b
0
5
b
0
4
b
0
3
PD17072,17073
b
0
2
b
0
1
b
0
0