Filter
Top Products
FR81 Family
8 FUJITSU MICROELECTRONICS LIMITED CM71-00105-1E
CHAPTER 2 MEMORY ARCHITECTURE
2.1
2.1 Address Space
The address space of FR81 Family CPU is 32 bits (4Gbyte).
CPU controls the address spaces in byte units. An address on the address space is accessed from the CPU
by specifying a 32-bit value. Address space is indicated in Figure 2.1-1.
Figure 2.1-1 Address space
Address space is also called memory space. It is a logical address space as seen from the CPU. Addresses
cannot be changed. Logical address as seen from the CPU, and the physical address actually allocated to
memory or I/O are identical.
2.1.1 Direct Address Area
In the lower address in the address space, there is a direct address area.
Direct address area directly specifies an address in the direct address specification instruction. This area
accesses only based on operand data in the instruction without the use of general-purpose registers. The
size of the address area that can be specified by direct addressing varies according to the data type being
accessed.
The correspondence between data type and area specified by direct address is as follows.
• byte data access: 0000 0000
H
to 0000 00FF
H
• half-word data access: 0000 0000
H
to 0000 01FF
H
• word data access: 0000 0000
H
to 0000 03FF
H
The method of using the 8-bit address data contained in the operand of instructions that specify direct
addresses is as follows:
0000 0000 H
0000 0100 H
0000 0200 H
0000 0400 H
000F FC00H
0010 0000H
FFFF FFFFH
Byte data
Half-word data
Word data
Vector table
initial area
Program or data area
000F FC00
H TBR
TBR initial value
Direct address area
General addressing