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CM71-00105-1E FUJITSU MICROELECTRONICS LIMITED 11
FR81 Family
CHAPTER 2 MEMORY ARCHITECTURE
2.1
2.1.3 20-bit Addressing Area & 32-bit Addressing Area
The lower portion of the address space extending from 0000 0000
H
to 000F FFFF
H
(1Mbyte) will be the
20-bit addressing area. The overall address space from 0000 0000
H
to FFFF FFFF
H
will be 32-bit
addressing space.
If all the program locations and data locations are positioned within the 20-bit addressing area, a compact
and high-speed program can be realized as compared to a 32-bit addressing area.
In a 20-bit addressing area, as the address values are within 20 bits, the LDI:20 instruction can be used for
immediate loading of address information. The instruction length (Code size) of LDI:20 instruction is
4bytes. By using LDI:20 instruction, the program becomes more compact than when using LDI:32
instruction of instruction length 6bytes.
Example of 20-bit Addressing
Code size
LDI:20 #label20,Ri ; 4 bytes
JMP @Ri ; 2 bytes
Total 6 bytes
Example of 32-bit Addressing
Code size
LDI:32 #label32,Ri ; 6 bytes
JMP @Ri ; 2 bytes
Total 8 bytes