Fig. 2.14 Example Of Transfer Between Al And Ah Of Accumulator (A) (8-Bit Immediate Value, Zero-Extended); Fig. 2.15 Example Of Transfer Between Al And Ah Of Accumulator (A) (8-Bit Immediate Value, Sign-Extended) - Fujitsu MB90420/5 (A) Series Hardware Manual

• Byte processing arithmetic operation of accumulator
When the arithmetic operation instruction for byte processing is executed for the AL register, the upper 8
bits of the pre-operation AL register are ignored, and the upper 8 bits of the operation result become all 0s.
• Initial value of accumulator
The initial value after reset is undefined.
MOV A, 3000
H
Before execution
After execution
Fig. 2.14 Example of Transfer between AL and AH of Accumulator (A)
MOVW A, 3000
Before execution
After execution
Fig. 2.15 Example of Transfer between AL and AH of Accumulator (A)
(This instruction zero-extends the data at address 3000
AL register.)
AH AL
XXXX 2456
H
DTB
2456 0088
H
(8-bit immediate value, zero-extended)
(This instruction stores the data at address 3000
H
AH AL
XXXX 2456
H
DTB
2456 7788
H
(8-bit immediate value, sign-extended)
CPU
B53000
H
H
B5
H
H
in the AL register.)
H
B53000
H
H
B5
H
H
2-17
and stores the extended data in the
H
Memory space
MSB
77 88
H H
X : Undefined
MSB : Most Significant Bit
LSB : Least Significant Bit
DTB : Data bank register
Memory space
MSB
77 88
H H
X : Undefined
MSB : Most Significant Bit
LSB : Least Significant Bit
DTB : Data bank register
LSB
LSB