	EXAMPLE of xdb SESSION
	
	o Invoke the debugger:
		$ xdb main
	
	o xdb displays a split screen 
	
		* C source displays in top half
	
		   - '>' points at the current location 
	
		   - Current location is NOT necessarily next line to be
		   executed
	
		* Debug output and user I/O display in lower half
	
		   - Displays any warnings, number of procedures and files.
	
		* Status line displays in reverse vides 
	
		   - Displays current file, procedure and line number
	
		* If there was a core file, it will be read in at procedure invocation.
		
	o Set up the first breakpoint in main:
	
		>b
	
	o Start execution, sending one command line argument:
	
		>r ARGUMENT
	
	o Set several consecutive breakpoints, one per successive line:
	
		>b    to set up breakpoint on the current line
		>+    to increment current line by one
		>b
		>+
		>b
		>+
		>b
		>+
		>b
		>+
		>b
		>+
		>b
		
		* Note the '*' that displays in column 1 of each breakpoint line.
	
		* Note that breakpoints may be set only on executable statements, not
		declarations.
	
		* If the current line is not an executable statement, the breakpoint is
		set on the executable statement closest to the current line.
	
	o Verify the previously set breakpoints:
	
		>lb
	
		* Note the breakpoint numbers associated with each of the previously set
		breakpoints.
	
	o Delete the breakpoints set on the individual lines:
	
		>lb
		>db 1
		>db 2
		>db 3
		...
	
		* This could also be accomplished by deleting all breakpoints at once:
	
		>db *
	
	o Find the line number in the source for the statement "first (&rad);":
	
		>/first (&rad);
	
	o Set a breakpoint on this line:
	
		>b 18
	
	o Execute the program until the first breakpoint:
	
		>c
	
		* The program will suspend execution just prior to the execution of the 
		displayed breakpoint line.
	
	o Step into the function 'first':
	
		>s
	
		* The displayed source is now within the function 'first'.
	
		* Each of the lines within the procedure may be indivually executed
		(ie: stepped).
	
	o Step until control is resumed by main:
	
		>s
		>s
		>s
	
		*The displayed source is now back in the main procedure.
	
	o Set a breakpoint at the procedure 'num_compare':
	
		>b num_compare
	
	o Examine the contents of 'rad' within main:
	
		>p main:rad
	
	o Step up to the 'printf' statement:
	
	o It is not possible to step INTO system calls and shared library calls.  To step
	OVER a function, try:
	
		>S
	
		* If 's' was tried, the debug session may be restarted by entering 'r'.
	
		* Note the value of 'circum' that displayed.
	
	o Deposit a different value into 'rad', and verify:
	
		>p rad=192
		>p rad
	
	o Continue to the next breakpoint:
	
		>c
	
	o Execution is now within the function 'num_compare'.  
	
	o Set a breakpoint at the end of the function and continue to that point:
		
		>bx
		>c
	
	o Examine the value in 'diff'.
	
		>p diff
	
	o Step back into the main procedure.
	
		>s
	
	o Continue the execution of the program:
	
		>c
	
		* Note the program results.  Apparently there is a logic error.  Can you
		find it?
	
	
	o Exit the debugger:
		
		>q
