Table of Contents
Advertisement
Debugger General Information
Calling System Utilities from User Programs
B
Preserving the Debugger Operating
Environment
177Bug Vector Table and Workspace
B-36
A convenient way of doing character input/output and many other
useful operations has been provided so that you do not have to
write these routines into the target code. You can access various
177Bug routines via one of the MC68060 TRAP instructions, using
vector #15. Refer to the Debugging Package for Motorola 68K CISC
CPUs User's Manual for details on the various TRAP #15 utilities
available and how to invoke them from within a user program.
This section explains how to avoid contaminating the operating
environment of the debugger. 177Bug uses certain of the MVME177
onboard resources and also offboard system memory to contain
temporary variables, exception vectors, etc. If you disturb resources
upon which 177Bug depends, then the debugger may function
unreliably or not at all.
If your application enables translation through the Memory
Management Units (MMUs), and if your application utilizes
resources of the debugger (e.g., system calls), your application must
create the necessary translation tables for the debugger to have
access to its various resources.The debugger honors the enabling of
the MMUs; it does not disable translation.
As described in the Memory Requirements section in Chapter 3,
177Bug needs 64KB of read/write memory to operate. The 177Bug
reserves a 1024-byte area for a user program vector table area and
then allocates another 1024-byte area and builds an exception
vector table for the debugger itself to use. Next, 177Bug:
Reserves space for static variables
Initializes these static variables to predefined default values
Advertisement
Table of Contents
