The COMMAND option

The COMMAND option tells IDF that the string following a slash (⁄) is not an argument string to be passed to your program, but is instead a command that it should issue to begin the debugging operation.

This COMMAND is LINKed to, and if it is an EXEC, you must precede it with a percent (%) sign. The percent sign signifies an implicit EXEC, and the command string is passed to the EXEC command for execution.

You can use this technique to debug user-area programs that need environmental setup.

When the COMMAND option is specified:

IDF starts, but the registers and PSW are not displayed if the Current Registers window or Old Registers window is open.
Set a breakpoint at the start of your program, or set a deferred breakpoint with the DBREAK command, and then press the RUN key.
IDF then issues the command you specified.
When the breakpoint is reached, IDF issues a message to tell you that it has reached a breakpoint.
The registers and PSW are now available for inspection and modification. Before the first breakpoint, IDF does not display the registers and PSW.