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3.2.7
Bank Register (PCB, DTB, USB, SSB, and ADB)
The bank register sets the MSB 8 bit of the 24-bit address using bank addressing The
following five registers are included.
• Program bank register (PCB)
• Data bank register (DTB)
• User stack bank register (USB)
• System stack bank register (SSB)
• Additional bank register (ADB)
Each of the above registers indicate the memory bank to which the program, data, user
stack, system stack, or additional is allocated.
I Program bank register (PCB)
The program bank register (PCB) sets the program (PC) space.
This register is rewritten at execution of the JMPP, CALLP, RETP, or RETI instructions that branches to
the entire 16-MB space, at executing a software interrupt instruction, or at a hardware interrupt or
exception interrupt.
I Data bank register (DTB)
The data bank register (DTB) sets the data (DT) space.
I User Stack Bank Register (USB) and System Stack Bank Register (SSB)
The user stack bank register (USB) and system stack bank register (SSB) set the stack (SP) space. The bank
register that is used is determined by the value of the stack flag (CCR: S).
I Additional bank register (ADB)
The additional bank register (ADB) sets the additional (AD) space.
I Setting of Each Bank and Data Access
Each bank register is 8 bits long. At a reset, the program bank register (PCB) is set to "FF
registers are set to "00
The program bank register (PCB) is a read-only register. Other bank registers are read and write registers.
Note:
For the operation of each bank register, see 3.1" Memory Space".
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CHAPTER 3 CPU
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