BreaK-PoinT

NAME
	BKPT -- Break-point

SYNOPSIS
	BKPT	#<data>

FUNCTION
	This instruction is used to support the program breakpoint
	function for debug monitors and real-time hardware emulators, and
	the operation will be dependent on the implementation. Execution of
	this instruction will cause the MC68010 to run a breakpoint
	acknowledge bus cycle and zeros on all address lines, but an
	MC68020 will place the immediate data on lines A2, A3, and A4, and
	zeros on lines A0 and A1.

	Whether the breakpoint acknowledge cycle is terminaled with
	 _____    ____       ___  
	(DTACK), (BERR), or (VPA) the processor always takes an illegal
	instruction exception. During exception processing, a debug monitor
	can distinguish eight different software breakpoints by decoding the
	field in the BKPT instruction.

	For the MC68000 and the MC68HC000, this instruction causes an illegal
	instruction exception, but does not run the breakpoint acknowledge
	bus cycle.

	There are two possible responses on an MC68020: normal and exception.
	The normal response is an operation word (typically the instruction
                                                                  ______
	the BKPT originally replaced) on the data lines with the (DSACKx)
	signal asserted. The operation word is the executed in place of the
	breakpoint instruction.

	For the exception response, a bus error signal will cause the MC68020
	to take an illegal instruction exception, just as an MC68010 or
	MC68000 would do.

FORMAT
	-----------------------------------------------------------------
	|15 |14 |13 |12 |11 |10 | 9 | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 |
	|---|---|---|---|---|---|---|---|---|---|---|---|---|-----------|
	| 0 | 1 | 0 | 0 | 1 | 0 | 0 | 0 | 0 | 1 | 0 | 0 | 1 |N BREAKPT.|
	-----------------------------------------------------------------

	Number of break-point: Value between 0 and 7.

RESULT
	None.

SEE ALSO
	ILLEGAL   

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