274
APPENDIX
B.3
Special Instructions
This section describes the special instructions used for other than addressing.
■
Special instructions
●
JMP @A
This instruction sets the contents of A (accumulator) to PC (program counter) as the address, and causes a
branch to that address. One of the N branch destination addresses is selected from a table, and then
transferred to A. The instruction can be executed to perform N-branch processing.
Figure B.3-1 "JMP @A" shows a summary of the instruction.
Figure B.3-1 JMP @A
●
MOVW A, PC
This instruction performs the operation which is the reverse of that performed by JMP @A. That is, the
instruction stores the contents of PC in A. When the instruction is executed in the main routine, so that a
specific subroutine is called, whether A contains a predetermined value can be checked by the subroutine.
This can be used to determine that the branch source is not any unexpected section of the program and to
check for program runaway.
Figure B.3-2 "MOVW A, PC" shows a summary of the instruction.
Figure B.3-2 MOVW A, PC
After the MOVW A, PC instruction is executed, A contains the address of the operation code of the next
instruction, rather than the address of the operation code of MOVW A, PC. Accordingly, Figure B.3-2
"MOVW A, PC" shows that A contains 1234
H
, which is the address of the operation code of the instruction
that follows MOVW A, PC.
1 2 3 4
H
A
X X X X
H
Previous PC
A
Current PC
(Before execution)
(After execution)
1 2 3 4
H
1 2 3 4
H
A
A
X X X X
H
1 2 3 4
H
1 2 3 4
H
1 2 3 4
H
Previous PC
Current PC
Summary of Contents for MB89950 Series
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Page 3: ...FUJITSU LIMITED F2MC 8L 8 BIT MICROCONTROLLER MB89950 950A Series HARDWARE MANUAL ...
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Page 34: ...20 CHAPTER 2 HANDLING DEVICES ...
Page 134: ...120 CHAPTER 6 WATCHDOG TIMER ...
Page 236: ...222 CHAPTER 10 UART ...
Page 276: ...262 CHAPTER 12 LCD CONTROLLER DRIVER ...
Page 310: ...296 APPENDIX ...
Page 311: ...297 INDEX INDEX The index follows on the next page This is listed in alphabetic order ...
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