Jump Instructions and
Subroutine Programming
Chapter 11
114
Table 11.A
Jump/Subroutine Programming
Key Symbol
Instruction Name
1770T3 Display
Description
SBR
T.END
SUBROUTINE AREA
SUBROUTINE AREA
Establishes the boundary between Main Program and
Subroutine Area. Subroutine Area is not scanned unless
directed to do so by a JSR instruction.
LBL
-(JMP)-
LABEL
XX
-LBL-
This condition instruction is the target destination for JMP
and JSR instructions.
XX - twodigit octal identification number, 0007.
LBL
-(JMP)-
JUMP
XX
-(JMP)-
When rung is TRUE, processor jumps forward to the
referenced LABEL in Main Program.
XX - twodigit octal identification number. Same as LBL
with which it is used.
-(RET)-
-(JSR)-
JUMP TO SUBROUTINE
XX
-(JSR)-
When rung is TRUE, Processor jumps to referenced
LABEL in Subroutine Area.
XX - twodigit octal identification number. Same as LBL
with which it is used.
-(RET)-
-(JSR)-
RETURN
-(RET)-
No identification number. Can be used unconditionally.
Returns Processor to instruction immediately following the
JSR that initiated the jump to subroutine.
Figure 11.3
Multiple JUMPS to LABEL in User Program
Main Program
( JMP )
01
||
()
LBL
01
||
| / |
||
( JMP )
01
||
||
||
( JMP )
01
| / |
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