iX Computer Systems - Edition 1 (32715-90001)

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| STEP | Command | Executes next line of suspended program and |

| | | suspends program at line following it. |

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| Trace Statements | Either | See Table 2-8. |

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| Untrace Statements | Either | See Table 2-9. |

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Table 2-7 Note

* The PAUSE statement is defined in chapter 4.

Busy Lines and Busy Subunits

A line is

busy

if one of the following is true:

* The line made a call that has not returned.

* The line was interrupted with the halt key before it finished

executing. (Not all lines can be interrupted in this way. A PRINT

statement is an example of a line that cannot be busy.)

A busy line cannot be modified or deleted.

A subunit is

busy

if it has been called, but has not returned.

A busy subunit can be modified, but not deleted. When modifying a

subunit, observe the following restrictions:

* A busy SUB statement can only be changed to another SUB statement.

* A busy DEF statement can only be changed to another DEF statement.

Numeric type variables can only be changed to another numeric type.

The type cannot be changed from numeric to string or vice versa.

* Changes to the subunit header take effect the next time the subunit

is called.

To make other header changes to a busy DEF or SUB statement, you must

first stop the program with the STOP command (chapter 4 explains the STOP

command).

CALLS Command

The CALLS command prints the names of busy program units on the system

printer or another device. (The SEND SYSTEM OUTPUT TO statement

specifies the device; see chapter 6.) The CALLS command is a

command-only statement. That is, it can only be issued at the

interpreter prompt and cannot be placed in a program.