user manual

Preserving the Debugger Operating Environment

MVME162IG/D2 4-11

Exception Vectors Used by 162Bug

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.

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 162Bug

Vec to r

Offset

Exception 162Bug 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 1 Level 7 interrupt ABORT pushbutton

$NOTE 2 Level 7 interrupt AC Fail

$DC FP Unimplemented Data Type Software emulation and data type

conversion of floating point data.

NOTES: 1. This depends on what the Vector Base Register (VBR) is set to in the

MCchip.

2. This depends on what the Vector Base Register (VBR) is set to in the

VMEchip2.