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MB90420/5 (A) SERIES F
2.7 Dedicated Registers
The CPU has following 11 dedicated registers.
• 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)
n Configuration of dedicated registers
Figure 2.12 shows the configuration of the dedicated registers, and Table 2-3 shows their initial values.
AH
AL
USP
SSP
PS
PC
DPR
PCB
DTB
USB
SSB
ADB
8 bits
16 bits
32 bits
2
MC-16LX FAMILY 16-BIT MICROCONTROLLERS HARDWARE MANUAL
:
Accumulator (A)
The accumulator includes two registers, each consisting of 16 bits, and is used to store operation results, etc.
It can also be used as one 32-bit register.
:
User stack pointer (USP)
This is a 16-bit pointer that indicates the user stack address.
:
System stack pointer (SSP)
This is a 16-bit pointer that indicates the system stack address.
:
Processor status (PS)
This is a 16-bit register that indicates the system status.
:
Program counter (PC)
This is a 16-bit register that indicates the current instruction store location.
:
Direct page register (DPR)
This is an 8-bit register that specifies bit 8 to 15 of the operand address at abbreviated direct addressing.
:
Program bank register (PCB)
This is an 8-bit register that indicates the program space.
:
Data bank register (DTB)
This is an 8-bit register that indicates the data space.
:
User stack bank register (USB)
This is an 8-bit register that indicates the user stack space.
:
System stack bank register (SSB)
This is the 8-bit register that indicates the system stack space.
:
Additional bank register (ADB)
This is an 8-bit register that indicates the additional space.
Fig. 2.12 Configuration of Dedicated Registers
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