Chapter 7 Ppcbug Firmware; Memory Requirements - Motorola MVME2700 Series Installation And Use Manual

PPCBug Firmware

Memory Requirements

7
Implementation
7-2
Because PPCBug is command-driven, it performs its various operations in
response to user commands entered at the keyboard. 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
(for instance, GO), then control may or may not return to PPCBug,
depending on the outcome of the user program. The flow of control in
PPCBug is described in the PPCBug Firmware Package User's Manual.
PPCBug is similar to previous Motorola firmware debugging packages
(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 total of 768KB of read/write memory (for example,
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.
Computer Group Literature Center Web Site