GEPPCBug Firmware Package User’s Manual Parts 1 & 2

or board.

The debugger includes:

❏ Commands for display and modification of memory

❏ Breakpoint and tracing capabilities

❏ Assembler and disassembler useful for patching programs

Various PPCBug routines that handle I/O, data conversion, and 

string functions are available to user programs through the System 

Call handler.

Because PPCBug is command-driven, it performs its various 

operations in response to user commands entered at the keyboard.

Comparison with other Motorola Bugs

The PPCBug is similar to previous Motorola firmware packages 

(e.g., MVME147Bug, MVME167Bug, MVME187Bug), with 

differences due to microprocessor architectures. These differences 

are primarily reflected in the instruction mnemonics, register 

displays, addressing modes of the assembler/disassembler, and 

argument passing to the system calls.

PPCBug Implementation

PPCBug is written largely in the C programming language, 

providing benefits of portability and maintainability. Where 

necessary, the assembly language has been used in separately 

compiled program modules that deal with processor-specific 

issues. No mixed-language modules are used.

Physically, PPCBug is contained in two socketed 32-pin PLCC 

Flash devices that together provide 1MB (256KB words) of storage. 

PPCBug uses the entire memory contained in the two devices. 

The executable code is checksummed at every power-on or reset 

firmware entry. The result is checked with a pre-calculated 

checksum contained in the last 16-bit word of the Flash image.

!

Caution

Although a command to allow the erasing and 

reprogramming of this Flash memory is available to 

you, keep in mind that reprogramming any portion of 

Flash memory will erase everything currently contained 

in Flash, including PPCBug.

Memory Requirements

The debugger requires approximately 768KB of read/write 

memory (i.e., DRAM). The debugger will allocate this memory 

from the top of memory. For example, on a system which contains 

64MB ($04000000) of read/write memory, the debugger's memory 

page will be located at $03F80000 to $03FFFFFF.

Size and Address Requirements for NVRAM

Currently, Motorola uses the SGS-Thompson Timekeeper SRAM 

device (48T559), or equivalent. This is used on the PowerPlus 

boards and is structured by the Debugger as follows:

NVRAM = 8192 bytes total size (with rtc)

Address ranges include:

Set-up

Refer to the board installation and use manual for information on 

installing the hardware, configuring jumpers, and assigning the 

console monitor.

Start-up

At either power-up or system reset, PPCBug performs the MPU, 

hardware, and firmware initialization process (refer to MPU, 

Hardware, and Firmware Initialization on page 1-5). This process 

includes a checksum of the FLASH memory contents.

The following types of messages are displayed on the firmware 

console during the initialization process:

Copyright Motorola Inc. 1988 - 1997, All Rights Reserved 

PPC1 Debugger/Diagnostics Release Version 3.x - xx/xx/xx/RMxx 

COLDStart 

Local Memory Found =04000000 (&67108864) 

MPU Clock Speed =167Mhz 

BUS Clock Speed =67Mhz

Reset Vector Location : ROM Bank B

Mezzanine Configuration: Single-MPU

Current 60X-Bus Master : MPU0

Idle MPU(s) : NONE

System Memory: 64MB, ECC Enabled (ECC-Memory Detected)

L2 Cache: NONE

PPC1-Bug>

At this point, PPCBug is waiting for you to enter one of the 

commands described in Chapter 3 of this manual.

PPCBug may alternatively be configured via the ENV command to 

run selftest and/or autoboot automatically during startup. If so, 

then PPCBug will instead behave as follows:

The system pauses five seconds, during which you may terminate 

start-up, and exit to the diagnostics prompt, by pressing ESC or the 

Break key

The system performs the self test diagnostics if you do not 

terminate system start-up. Upon successful completion of these 

tests, the system pauses another five seconds. You may terminate 

start-up, and exit to the diagnostics prompt, by pressing ESC or the 

Break key.

If you do not terminate system start-up, the system begins the boot 

routine that has been set up in the ENV command, either NVRAM 

Boot List Boot, Auto Boot, ROMboot, or Network Auto Boot.

If the self-tests fail, various error messages appear, and the 

diagnostics prompt appears.

Refer to Chapter 3 for information on setting the ENV command 

parameters.

MPU, Hardware, and Firmware Initialization

The MPU, hardware, and firmware initialization process is 

performed by the PPCBug power-up or system reset. The steps 

below are a high-level outline; not all of the detailed steps are listed.

1. Set MPU.MSR to known value.

2. Invalidate the MPU's data/instruction caches.

3. Clear all segment registers of the MPU.

4. Clear all block address translation registers of the MPU.

5. For “dual CPU only” boards (MVME460x or MTX), catch one 

CPU of a dual CPU and place it in a waiting loop.

6. Initialize the MPU bus to PCI bus bridge device.

7. Initialize the PCI bus to ISA bus bridge device.