D17133CS datasheet(113/289 Pages) NEC

113 / 289 page

CHAPTER 11

ARITHMETIC AND LOGIC UNIT

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>

SKT

M1,

#1101B

; <2>

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>

SKT

M1,

#1101B

; <2>

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.

D17133CS Datasheet(PDF) 113 Page - NEC