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CHAPTER 2 CPU
2.7
Dedicated Registers
The following 11 registers are dedicated registers in the CPU.
Accumulator (A)
User stack pointer (USP)
System stack pointer (SSP)
Processor status (PS)
Program counter (PC)
Direct page register (DPR)
Program bank register (PCB)
Data bank register (DTB)
User stack bank register (USB)
System stack bank register (SSB)
Additional data bank register (ADB)
s Configuration of Dedicated Registers
Figure 2.7-1 Configuration of Dedicated Registers
AH
AL
USP
SSP
PS
PC
DPR
PCB
DTB
USB
SSB
ADB
: Accumulator (A)
Two 16-bit registers used for the storage of arithmetic operation results.
The two registers can be combined as a contiguous 32-bit register.
: User stack pointer (USP)
16-bit stack pointer that indicates the user stack address
: System stack pointer (SSP)
16-bit stack pointer that indicates the system stack address
: Processor status (PS)
16-bit status register that indicates the system status
: Program counter (PC)
16-bit count register that indicates the current instruction storage location
: Program bank register (PCB)
8-bit bank register that indicates the program space
: Data bank register (DTB)
8-bit bank register that indicates the data space
: User stack bank register (USB)
8-bit bank register that indicates the user stack space
: System stack bank register (SSB)
8-bit bank register that indicates the system stack space
: Additional data bank register (ADB)
8-bit bank register that indicates the additional space
: Direct page register (DPR)
8-bit page register that specifies bits 8 to 15 of the operand address
when the short direct addressing is executed
8 bits
16 bits
32 bits