Personal Computer User Manual

Debugger General Information

3-2 Installation Guide

the diagnostic prompt “197-Diag>” is displayed and the user has all of the

diagnostic commands at his disposal as well as all of the debugger commands.

The user may switch between directories by using the Switch Directories (SD)

command, or may examine the commands in the particular directory that the

user is currently in by using the Help (HE) command.

Because 197Bug is command-driven, it performs its various operations in

response to user commands entered at the keyboard. When a command is

entered, 197Bug executes the command and the prompt reappears. However,

if a command is entered which causes execution of user target code (e.g.,

“GO”), then control may or may not return to 197Bug, depending on the

outcome of the user program.

Comparison With M68000-Based Firmware

Those users who have used one or more of Motorola's other debugging

packages will find 197Bug very similar, after making due allowances for the

architectural differences between the M68000 and M88000 CPU architectures.

These are primarily reflected in the instruction mnemonics and addressing

modes of the assembler/disassembler, and in the use of registers instead of the

stack for the passing of arguments to or from the TRAP #496 handler. Some

effort has also been made to make the interactive commands more consistent.

For example, delimiters between commands and arguments may now be

commas or spaces interchangeably.

197Bug Implementation

MVME197BUG is written largely in the “C” programming language,

providing benefits of portability and maintainability. Where necessary,

assembler has been used in the form of separately compiled modules

containing only assembler code - no mixed language modules are used.

Physically, 197Bug is contained in the onboard flash memory. The executable

code is checksummed at every power-on or reset firmware entry, and the

result (which includes a pre-calculated checksum contained in the flash

memory), is tested for an expected zero. Thus, users are cautioned against

modification of the flash memory unless re-checksum precautions are taken.

Installation and Start-up

Even though the MVME197Bug flash memory devices are installed on the

MVME197LE module, for 197Bug to operate properly with the MVME197LE,

follow this set-up procedure.