CHAPTER 11 ARITHMETIC AND LOGIC UNIT
98
11.5.1 TRUE (1) Bit Judgement
The TRUE (1) bit judgement instruction (SKT m, #n) is used to determine whether or not the bits specified by n
in the four bits of data memory m are TRUE (1). When all bits specified by n are TRUE (1), this instruction causes
the next instruction to be skipped.
Example
MOV
M1,
#1011B
SKT
M1,
#1011B
; <1>
BR
A
BR
B
SKT
M1,
#1101B
; <2>
BR
C
BR
D
In this example, bit 3, 1, and 0 of data memory M1 are judged in step number <1>. Because all the
bits are TRUE (1), the program branches to B. In step number <2>, bits 3, 2 and 0 of data memory
M1 are judged. Since bit 2 of data memory M1 is FALSE (0), the program branches to C.
11.5.2 FALSE (0) Bit Judgement
The FALSE (0) bit judgement instruction (SKF m, #n) is used to determine whether or not the bits specified by
n in the four bits of data memory m are FALSE (0). When all bits specified by n are FALSE (0), this instruction causes
the next instruction to be skipped.
Example
MOV
M1,
#1011B
SKT
M1,
#0110B
; <1>
BR
A
BR
B
SKT
M1,
#1101B
; <2>
BR
C
BR
D
In this example, bits 2 and 1 of data memory M1 are judged in step number <1>. Because both bits
are FALSE (0), the program branches to B. In step number <2> bits 3, 2, and 1 of data memory M1
are judged. Since bit 3 of data memory M1 is TRUE (1), the program branches to C.
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