Motorola MVME166IG/D2, MVME166D2 manual 2. Exception Vectors Used by 166Bug

Preserving the Debugger Operating Environment

Exception Vectors Used by 166Bug

The exception vectors used by the debugger are listed below. These vectors must reside at the specified offsets in the target program’s vector table for the associated debugger facilities (breakpoints, trace mode, etc) to operate.

Table 4-2. Exception Vectors Used by 166Bug

	Vector	Exception	166Bug Facility
	Offset
$10	Illegal instruction	Breakpoints (used by GO, GN, GT)
$24		Trace	Trace operations (such as T, TC, TT)
	$80-$B8	TRAP #0 - #14	Used internally
	$BC	TRAP #15	System calls
	$NOTE	Level 7 interrupt	ABORT pushbutton
	$NOTE	Level 7 interrupt	AC Fail
	$DC	FP Unimplemented Data Type	Software emulation and data type
			conversion of floating point data.

NOTE: These depend on what the Vector Base Register (VBR) is set to in the VMEchip2.

When the debugger handles one of the exceptions listed in Table 4-2, the target stack pointer is left pointing past the bottom of the exception stack frame created; that is, it reflects the system stack pointer values just before the exception occurred. In this way, the operation of the debugger facility (through an exception) is transparent to users.

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MVME166IG/D2 4-11