Document revision date: 30 March 2001
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Guide to the DEC Text Processing Utility

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Appendix C
DECTPU Debugger Commands

You can use the following commands for debugging once you have set breakpoints, compiled code, and started execution.

ATTACH process

Suspends the current editing session and transfers control to another active process or subprocess.

DCL process names are case sensitive.

CANCEL BREAKPOINT procedure-name

Cancels a breakpoint set with the SET BREAKPOINT command.

DEPOSIT variable := expression

Lets you set the values of global variables, local variables, and formal parameters.


Clears text from the screen after use of the HELP or SHOW BREAKPOINTS command. Causes the source display area to display your code.

EXAMINE variable

Displays the current contents of global and local variables, global constants, formal parameters of the procedure that has been interrupted, and variables local to that procedure. Local constants cannot be examined.


Causes the debugger to relinquish control of execution until it is invoked again by a breakpoint, by the DEBUG command, or by the DEBUGON procedure.


Lists available debugger commands and keypad bindings.


Stops execution of the current procedure. Uses the ABORT statement to return to the main loop of DECTPU. This command is useful when you have located a problem in a procedure and are ready to get out of the procedure.

SCROLL [-] number-of-lines

Scrolls text in the source display area by the specified number of lines. To scroll backward through the code in the display area, specify a negative number of lines.

To scroll forward by one line less than the number of lines in the display window, press the Next Screen key or the sequence GOLD/Down Arrow. To scroll backward in the same way, press the Prev Screen key or the sequence GOLD/Up Arrow.

SET BREAKPOINT procedure-name

Invokes the debugger when the specified procedure is entered.

SET WINDOW top, length

Places the top of the debugger window at the line number specified by the top parameter. Extends the window down by the number of lines specified by the length parameter. The default length is 7 lines. The minimum valid length is 3 lines. The SET WINDOW command changes only the size of the source display area. The output area and command line always occupy exactly one line.

SHIFT [-] number-of-columns

Moves the source display window left or right across the source code to display text wider than the screen.

To move left, you press the key sequence GOLD/Left Arrow, then enter the number of columns to move. To move right, you press the key sequence GOLD/Right Arrow, then enter the number of columns to move.


List the current breakpoints in the debugger source window. To redisplay code in the source window, use the DISPLAY SOURCE command.

SPAWN subprocess

Suspends the current editing session and creates a new process.


Executes one line of DECTPU code, then returns control to the debugger. If you have several DECTPU statements on one line, all statements are executed before control returns to the debugger.

TPU statement

Executes the DECTPU statement you specify. You can enter more than one statement by using the TPU command just once.

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