Memory Requirements; Ppcbug Implementation - Motorola MVME2603-1121A Installation And Use Manual

Overview
5

Memory Requirements

PPCBug Implementation

5-2
Because PPCBug is command-driven, it performs its various
operations in response to user commands entered at the keyboard.
The flow of control in PPCBug is described in the PPCBug Firmware
Package UserÕs Manual. When you enter a command, PPCBug
executes the command and the prompt reappears. However, if you
enter a command that causes execution of user target code (e.g.,
GO), then control may or may not return to PPCBug, depending on
the outcome of the user program.
The PPCBug is similar to previous Motorola firmware debugging
packages (e.g., MVME147Bug, MVME167Bug, MVME187Bug),
with differences due to microprocessor architectures. These are
primarily reflected in the instruction mnemonics, register displays,
addressing modes of the assembler/disassembler, and the passing
of arguments to the system calls.
PPCBug requires a maximum of 768KB (maybe less) of read/write
memory (i.e., DRAM). The debugger allocates this space from the
top of memory. For example, a system containing 64MB
($04000000) of read/write memory will place the PPCBug memory
page at locations $03F80000 to $03FFFFFF.
PPCBug is written largely in the C programming language,
providing benefits of portability and maintainability. Where
necessary, assembly language has been used in the form of
separately compiled program modules containing only assembler
code. No mixed-language modules are used.
Physically, PPCBug is contained in two socketed 32-pin PLCC
Flash devices that together provide 1MB of storage. The executable
code is checksummed at every power-on or reset firmware entry,
and the result (which includes a precalculated checksum contained
in the Flash devices), is verified against the expected checksum.