Figure 2.1.1C Physical Addresses Of Each Space; Table 2.1.1A Default Space - Fujitsu F2MC-16LX MB90580 Series Hardware Manual

2.1 CPU
The 64-Kbyte bank specified by the PCB is called a program (PC) space. The PC space contains
instruction codes, vector tables, and immediate value data, for example.
The 64-Kbyte bank specified by the DTB is called a data (DT) space. The DT space contains readable/
writable data, and control/data registers for internal and external resources.
The 64-Kbyte bank specified by the USP or SSP is called a stack (SP) space. The SP space is accessed
when a stack access occurs during a push/pop instruction or interrupt register saving. The S flag in the
condition code register determines the stack space to be accessed.
The 64-Kbyte bank specified by the ADB is called an additional (AD) space. The AD space, for example,
contains data that cannot fit into the DT space.
Table 2.1.1a lists the default spaces used in each addressing mode, which are pre-determined to improve
instruction coding efficiency. To use a non-default space for an addressing mode, specify a prefix code
corresponding to a bank before the instruction. This enables access to the bank space corresponding to
the specified prefix code.
After reset, the DTB, USB, SSB, and ADB are initialized to 00H. The PCB is initialized to a value
ified by the reset vector. After reset, the DT, SP, and AD spaces are allocated in bank 00H (000000H to
00FFFFH), and the PC space is allocated in the bank specified by the reset vector.
Default space
Program space
Data space
Stack space
Additional space
Figure 2.1.1c is an example of a memory space divided into register banks.
FFFFFF
H
FF0000
H
B3FFFF
H
B30000
H
92FFFF
H
920000
H
68FFFF
H
680000
H
4BFFFF
H
4B0000
H
000000
H
18 Chapter 2: CPU

Table 2.1.1a Default space

Addressing mode
PC indirect, program access, branch
Addressing mode using @RW0, @RW1, @RW4, or @RW5, @A, addr16, and dir
Addressing mode using PUSHW, POPW, @RW3, or @RW7
Addressing mode using @RW2 or @RW6
Program space
Additional space
User stack space
Data space
System stack space

Figure 2.1.1c Physical addresses of each space

FF : PCB (Program bank register)
H
: ADB (Additional bank register)
B3
H
92 : USB (User stack bank register)
H
: DTB (Data bank register)
68
H
4B
: SSB (System stack bank register)
H
spec-
MB90580 Series