Motorola MVME166IG/D2 - Manual (Page 81)

Preserving the Debugger Operating Environment
MVME166IG/D2 4-11
4
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.
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.
Table 4-2. Exception Vectors Used by 166Bug
Vector
Offset
Exception 166Bug Facility
$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.