Tandy 1000 Basic Reference Manual page 242

Chapter 10 I BASIC Keywords
ON TIMER() GOSUB
Statement
ON TIMER(number1 GOSUB line
Transfers program control to a subroutine when the specified pe-
riod of time has elapsed.
Number
indicates the number of seconds.
Number
may be a
value in the range 1 to 86400 (86400 seconds
=
24 hours).
Line is the first line number in the subroutine to execute when
the specified time has passed. If you specify Line 0, you turn off
trapping for the timer. Use RETURN
t o
exit the subroutine.
BASIC executes the ON TIMER0 GOSUB statement only if a
TIMER ON statement has been executed previously to enable
time event trapping.
If a TIMER STOP statement has been issued to halt time event
trapping temporarily, BASIC executes the subroutine immedi-
ately after the next TIMER
ON
statement.
When you execute the ON TIMER() GOSUB statement, BASIC
immediately issues a TIMER STOP to prevent recursive traps.
When BASIC executes the RETURN from the subroutine, it au-
tomatically executes another TIMER ON statement to enable
trapping again, unless the subroutine executes a TIMER
OFF
statement.
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