Memory Requirements; Ppcbug Implementation; Mpu, Hardware, And Firmware Initialization - Motorola MVME2100 Installation And Use Manual

Memory Requirements

PPCBug requires a maximum of 768KB of read/write memory. The
debugger allocates this space from the top of memory. For example, a
system containing 64MB (0x04000000) of read/write memory will place
the PPCBug memory page at locations 0x03F40000 to 0x03FFFFFF.

PPCBug Implementation

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.
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. The result
(which includes a precalculated checksum contained in the flash devices),
is verified against the expected checksum.

MPU, Hardware, and Firmware Initialization

The debugger performs the MPU, hardware, and firmware initialization
process. This process occurs each time the MVME2100 is reset or powered
up. The steps below are a high-level outline; not all of the detailed steps
are listed.
1. Sets MPU.MSR to known value.
2. Invalidates the MPU's data/instruction caches.
3. Clears all segment registers of the MPU.
4. Clears all block address translation registers of the MPU.
5. Initializes the MPU-bus-to-PCI-bus bridge device.
6. Initializes the PCI-bus-to-ISA-bus bridge device.
7. Calculates the external bus clock speed of the MPU.
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MPU, Hardware, and Firmware Initialization
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