Bank Registers (Pcb, Dtb, Usb, Ssb, Adb) - Fujitsu F2MC-16LX Hardware Manual

2.4.6

Bank registers (PCB, DTB, USB, SSB, ADB)

Using bank addressing, each bank register is set with the highest eight bits of a 24-bit
address. Bank registers can be classified into the following five types:
• Program bank register (PCB)
• Data bank register (DTB)
• User stack bank register (USB)
• System stack bank register (SSB)
• Additional data bank register (ADB)
The bank registers indicate the memory banks in which program, data, user stack,
system stack, and additional spaces are allocated.
■ Program Bank Register (PCB)
The program bank register (PCB) specifies the program (PC) space.
This register is rewritten at execution of the JMPP, CALLP, RETP, or RETI instruction that
branches to all 16 MB space, at execution of the software interrupt instruction, and at an
occurrence of a hardware interrupt or exception handling interrupt.
■ Data Bank Register (DTB)
The data bank register (DTB) specifies the data (DT) space.
■ User Stack Bank Register (USB) and System Stack Bank Register (SSB)
The user stack bank register (USB) and system stack bank register (SSB) specify the stack
(SP) space. The value of the stack flag (CCR:S) is the basis for determining which of the bank
registers is used.
■ Additional Data Bank Register (ADB)
The additional data bank register (ADB) specifies the additional (AD) space.
■ Settings and Data Access of Bank Registers
Each of the bank registers has a length of eight bits. The program bank register (PCB) is
initialized to FF
The program bank register (PCB) is a read-only register. The other bank registers are read-
write registers.
For information on bank register operations, see Section "2.1 Memory Space".
by a reset, while the other bank registers are initialized to 00
H
2.4 Dedicated Registers
.
H
41