Texas Instruments TI-99/4A

GOSUB
Within a subroutine, you may want the computer to jump to another
subroutine, complete it. (':rlmp: h;J~k to the first subroutine, complete
its steps, then return to the main program at the point where the
original
branch occurred. You can do this easily with the proper
pairing of GOSUB and RETURN <:.t;Jtp:lTIp.nts. However, be sure
you exercise care in designing subroutines so that the computer will
not "lose its place."
In
the example on the right, thc main program jumps to subroutInc
1 when it reaches line sao. In subroutine 1. when the program
reaches line 730, it goes to subroutine 2. When the RETURN in
subroutine 2 is encountered (line 850). the computer returns to
subroutine 1 at line 740, finishes the subroutine. returns to the main
prol2:fam and completes it through line 600.
If the GOSUB statement transfers the program to a line-number not
in the program, the prog;ram will end and the lTIe<:.<;;lp;e "BAD LiN E
NUMBER' will print. If the GOSUB transfers the program to its
own line·number. the program will stop and the message
"MEMORY FULL" will print.
User's Reference Guide
Examples:
>NEI<
>100 REM NESTED SUBROUTINES
~110 REM MAIN PROGRAM
>500 GOSU8 700
>510
>600 STOP
>700 REM SUBROUTINE1
>730 GOSLJB 800
>740
>790
RETURN
>800 REM SUBROUTINE2
>850 RETURN
>NEW
>100 X=12
>110 Y=23
>120 GOSUB 120
>130 PRINT Z
>140 STOP
>150 REM SUBROUTINE
>160 I=X+Y*120/5
>170 RETURN
;>IlUN
* MEMOR¥ FULL IN 120
>120 GOSUB 150
) RU N
564
** DONE **
II·llS