User’s Manual U11047EJ3V0UM00
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CHAPTER 2 REGISTERS
2.1 Control Registers
The control registers have dedicated functions such as controlling the program sequence, statuses, and stack
memory. The control registers include a program counter, program status word, and stack pointer.
2.1.1 Program counter (PC)
The program counter is a 16-bit register that holds the address information of the next program to be executed.
In normal operation, the PC is automatically incremented according to the number of bytes of the instruction to be
fetched. When a branch instruction is executed, immediate data and register contents are set.
When the
______________
RESET signal is input, the program counter is set to the value of the reset vector table, which are
located at addresses 0000H and 0001H.
Figure 2-1. Format of Program Counter
15
0
PC15 PC14 PC13 PC12 PC11 PC10 PC9
PC8
PC7
PC6
PC5
PC4
PC3
PC2
PC1
PC0
PC
2.1.2 Program status word (PSW)
Program status word is an 8-bit register consisting of various flags to be set/reset by instruction execution.
The contents of program status word are automatically stacked when an interrupt request is generated or when
the PUSH PSW instruction is executed and, are automatically reset when the RETI and POP PSW instruction are
executed.
______________
RESET input sets PSW to 02H.
Figure 2-2. Format of Program Status Word
7
0
IE
Z
0
AC
0
0
1
CY
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