Generally, the debugger lies in the background waiting for some catastrophic event to occur.
To bring up the debugger from the keyboard, press Ctl-Alt-Pad5. That is, with the Ctl- and Alt-keys held down, pressing the 5 key on the numeric pad invokes the debugger. This mechanism is useful when your program is stuck somewhere. Remember, the keyboard and the keyboard interrupt must be enabled for this to work. On systems for which the Pad5 key is inconvenient to use (such as some laptops), the sequence Ctl-Alt-SysReq also brings up the debugger.
It is also handy to install an NMI switch for when the system really gets locked up. Be sure to put the keyword TRAPNMI in the 386SWAT profile.
To run a particular program through the debugger, use the SWATRUN utility.
If remote debugging is active (see SETCOM profile option and SETCOM command) the debugger may also be activated by sending SWT! followed by a break signal. This is done by pressing Ctl-6 in the CHAT screen.
The utility SWATCMD (loaded via Device= or from the DOS command line) may be used to pass commands to 386SWAT. Invoking SWATCMD with no options brings up 386SWAT at an INT 03h (assuming TRAPSKIP or TRAPDEBUG is active).