Appendix
G:
BASIC
Statements 357
Availability Map (BAM) are initialized. The diskette
is
assigned the name
disk name and the number vv.
The diskette name and number are displayed in the reverse field
at
the
top of a directory display.
Example:
OPEN
1,9,15 Open the diskette command channel
ON·GOSUB
A diskette has beenpreparedjor use
in
drive
O.
The diskette
is
given the
name
NEWDATA
and the number
02
The ON-GOSUB statement provides conditional subroutine calls to
one of several subroutines in a program, depending on the current value of a
variable.
Format:
ON byte GOSUB line,[,line
2
,
...
,line
n
]
ON-GOSUB has the same format as ON-GOTO. Refer to the ON-
GOTO statement description for branching rules.
byte
is
evaluated and
truncated to an integer number, if necessary.
For
byte=l,
the subroutine beginning
at
line,
is
called.
That
subroutine
completes execution with a
RETURN
statement
that
causes program exe-
cution to continue
at
the statement immediately following ON-GOSUB.
If
byte=2, the subroutine beginning with line
2
is
called, and so on.
ON-GOSUB
is
normally executed in program mode.
It
may be exe-
cuted in immediate mode as long as there are corresponding line numbers to
branch to in the current stored program.
Example:
10
ON
A
GOSUB
100,200,300
ON·GOTO
The ON -GOTO statement causes a conditional branch to one
of
several
points in a program, depending on the current value of a variable.
Format:
ON byte GOTO line,[,line
2
,
...
,line
n
]
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