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CHAPTER 5 CPU
5.1
Dedicated Registers
The CPU has its dedicated registers: the program counter (PC), two arithmetic registers
(A and T), three address pointers (IX, EP, and SP), and the program status (PS) register.
Each of the registers is 16 bits long. The PS register consists of the register bank
pointer (RP), direct pointer (DP), and condition code register (CCR).
■
Configuration of Dedicated Registers
The dedicated registers in the CPU are seven 16-bit registers. Accumulator (A) and temporary accumulator
(T) can also be used with only their lower eight bits in service.
Figure 5.1-1 shows the configuration of the dedicated registers.
Figure 5.1-1 Configuration of Dedicated Registers
■
Functions of Dedicated Registers
●
Program counter (PC)
The program counter is a 16-bit counter which contains the memory address of the instruction currently
executed by the CPU. The program counter is updated whenever an instruction is executed or an interrupt
or reset occurs. The initial value set immediately after a reset is the mode data read address (FFFD
H
).
●
Accumulator (A)
The accumulator is a 16-bit register for arithmetic operation. It is used for a variety of arithmetic and
transfer operations of data in memory or data in other registers such as the temporary accumulator (T). The
data in the accumulator can be handled either as word (16-bit) data or byte (8-bit) data. For byte-length
arithmetic and transfer operations, only the lower eight bits (AL) of the accumulator are used with the
upper eight bits (AH) left unchanged. The initial value set immediately after a reset is 0000
H
.
Address
FFFD
H
PC
: Program counter
Contains the address of the current instruction.
0000
H
AH
AL
: Accumulator (A)
Temporary storage register for arithmetic operation and
transfer.
0000
H
TH
TL
: Temporary accumulator (T)
Performs an operation with accumulator.
0000
H
IX
: Index register
Register containing an index address.
0000
H
EP
: Extra pointer
Pointer containing a memory address.
0000
H
SP
: Stack pointer
Contains the current stack location.
0030
H
RP
DP
CCR
: Program status
Register consisting of the register bank pointer, direct bank
pointer, and condition code register.
16 bits
PS
Содержание F2 MC-8FX Family
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Страница 30: ...16 CHAPTER 1 DESCRIPTION 1 FPT 64P M23 FPT 64P M24 2 For the I O circuit type refer to 1 8 I O Circuit Type ...
Страница 34: ...20 CHAPTER 1 DESCRIPTION ...
Страница 35: ...21 CHAPTER 2 HANDLING DEVICES This chapter gives notes on using 2 1 Device Handling Precautions ...
Страница 38: ...24 CHAPTER 2 HANDLING DEVICES ...
Страница 39: ...25 CHAPTER 3 MEMORY SPACE This chapter describes memory space 3 1 Memory Space 3 2 Memory Map ...
Страница 43: ...29 CHAPTER 4 MEMORY ACCESS MODE This chapter describes the memory access mode 4 1 Memory Access Mode ...
Страница 56: ...42 CHAPTER 5 CPU ...
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Страница 104: ...90 CHAPTER 7 RESET ...
Страница 105: ...91 CHAPTER 8 INTERRUPTS This chapter explains the interrupts 8 1 Interrupts ...
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Страница 218: ...204 CHAPTER 13 WATCH PRESCALER ...
Страница 257: ...243 CHAPTER 16 8 16 BIT COMPOSITE TIMER ...
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Страница 430: ...416 CHAPTER 23 10 BIT A D CONVERTER ...
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Страница 482: ...468 CHAPTER 25 LOW VOLTAGE DETECTION RESET CIRCUIT ...
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Страница 564: ...550 CHAPTER 29 EXAMPLE OF SERIAL PROGRAMMING CONNECTION ...
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Страница 596: ...582 INDEX Index ...
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Страница 599: ...585 Pin Function Index V2 LCD power supply driving pin 2 439 V3 LCD power supply driving pin 3 439 ...
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