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CHAPTER 7 DETAILED EXECUTION INSTRUCTIONS
7.73 ST (Store Word Data in Register to Memory)
Subtracts 4 from the value of "R15", stores the word data in "Ri" to the memory address
indicated by the new value of "R15".
If "R15" is given as the parameter "Ri", the data transfer will use the value of "R15"
before subtraction.
■ ST (Store Word Data in Register to Memory)
Assembler format: ST Ri, @ – R15
Operation: R15 – 4 → R15
Ri → (R15)
Flag change:
N, Z, V, and C: Unchanged
Execution cycles: a cycle(s)
Instruction format:
Example: ST R3, @ – R15
NZVC
––––
MSB LSB
000101110000 Ri
12345674
R3R3
8765 4321
8765 4321
12345674
12345678 12345678
1234 5678
8765 4321
R15
1234 5674
R15
xxxx xxxx
Memory Memory
Before execution After execution
Instruction bit pattern : 0001 0111 0000 0011