CHAIN 'dev-address' ,arith-exp
60
CHAIN
The CHAIN statement performs the following sequence:
1. Ends
the
program currently being executed
2.
Loads a new program
3. Begins executing
the
new program
The syntax
of
the CHAIN statement
is
as
shown:
CHAI N 'dev-address' ,arith-exp
where:
'dev-address'
is
the
address
of
the device containing the next program
to
be loaded
and executed. Device address can
be
'ESO' (built-in tape unit) or
'E40'
(auxiliary
tape unit).
arith-exp
is
a simple expression
or
constant.
Upon execution
of
the
CHAIN statement, the expression
is
evaluated and truncated
to
an integer. This integer identifies
the
file containing
the
new program on
the
device specified. A simple constant can also be used.
All
open files
in
the
current
program are closed. The program
in
the
file (determined by
the
expression
or
con-
stant) on the device specified
is
then loaded and executed starting with the lowest
statement number.
For example:
0110 CHAIN 'ESO', 14
In
this statement, the program
in
file number 14 on device 'ESO' (built-in tape unit)
is
loaded and executed after the current program
is
terminated.
Note About CHAIN
When used
in
conjunction with the
USE
statement,
the
CHAI
N statement allows
variable values
to
be maintained from one program
to
the
next (see
USE
statement).
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