Bank Addressing - Fujitsu MB90895 Series Hardware Manual

3.1.5

Bank Addressing

The bank addressing is a type of addressing each of 254 64-KB banks into which the 16-
MB memory space is divided, using the bank register, and the lower 16 bits by an
instruction.
The following five types of bank registers are available for different purposes.
• Program bank register (PCB)
• Data bank register (DTB)
• User stack bank register (USB)
• System stack bank register (SSB)
• Additional bank register (ADB)
I Bank Registers and Access Space
Table 3.1-1"Access Space for Each Bank Register and Major Use of Access Space" shows the access space
for each bank register and the major use of it.
Table 3.1-1 Access Space for Each Bank Register and Major Use of Access Space
Bank Register Name
Program bank register (PCB)
Data bank register (DTB)
User stack bank register (USB)
System stack bank register (SSB)
Additional bank register (ADB)
*: SSB is always used for the stack at an interrupt.
Access Space
Program (PC) space
Data (DT) space
Stack (SP) space
*
Additional (AD) space
Major Use
Stores instruction code, vector tables, immediate data.
Stores data that can be read/written and can access
resource control registers and data registers.
These are used for the stack accessing such as the
PUSH/POP instruction and the register saving at an
interrupt. When the stack flag (CCR: S) is "1", SSB is
used. When the stack flag is "0", USB is used.
Stores data that cannot be stored in data (DT) space.
CHAPTER 3 CPU
Reset
Value
FF
H
00
H
00
H
00
H
*
00
H
27