GOSUB Keyword

GOSUB numeric-constant

Transfers control to the line with the given constant line number, saving the return address so that execution can continue at the statement after the GOSUB when a matching RETURN is encountered.

Remarks

Deprecated / discouraged.

Use structured procedures instead:

define with DEF PROCname(...) ... ENDPROC and call with PROCname(...).

GOSUB is retained for compatibility with legacy, line-numbered code.

• The target must be a numeric constant (no expressions or variables).
• The target line must exist within the current program.
• Each GOSUB must eventually reach a RETURN.

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Example: simple subroutine (line numbers permitted)

10 PRINT "Start"
20 GOSUB 1000
30 PRINT "Back from subroutine"
40 END
 
1000 PRINT "Inside subroutine"
1010 RETURN

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Example: using variables with a subroutine

10 N = 3
20 GOSUB 2000
30 PRINT "Done"
40 END
 
2000 PRINT "Counting..."
2010 FOR I = 1 TO N
2020     PRINT I
2030 NEXT
2040 RETURN

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Notes

• GOSUB does not support arguments. Share data via variables; prefer PROC parameters in new code.
• Jumping to a line that does not contain the intended subroutine body will execute whatever is there until a RETURN is hit.
• Modern Retro Rocket BASIC code should prefer DEF PROC / PROC for clarity and maintainability.

See also:
RETURN · DEF · PROC · GOTO