
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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