Motorola MVME187 User Manual
4-4
Debugger General Information
4
Comparison with M68000-Based Firmware
If you have used one or more of Motorola's other debugging
packages, you will find the RISC 187Bug very similar, after making
due allowances for the architectural differences between the
M68000 and M88000 CPU architectures. These differences are
primarily reflected as follows:
packages, you will find the RISC 187Bug very similar, after making
due allowances for the architectural differences between the
M68000 and M88000 CPU architectures. These differences are
primarily reflected as follows:
❏
Instruction mnemonics and addressing modes of the
assembler/disassembler differ somewhat in 187Bug.
assembler/disassembler differ somewhat in 187Bug.
❏
187Bug uses registers instead of the stack for the passing of
arguments to or from the TRAP #496 handler.
arguments to or from the TRAP #496 handler.
❏
The interactive commands in 187Bug are more consistent. For
example, delimiters between commands and arguments may
now be commas or spaces interchangeably.
example, delimiters between commands and arguments may
now be commas or spaces interchangeably.
187Bug Implementation
MVME187Bug is written largely in the ÒCÓ 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.
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, 187Bug is contained in two of the four 44-pin
PLCC/CLCC EPROMs, providing 512KB (128K words) of storage.
Both EPROMs are necessary regardless of how much space is
actually occupied by the firmware, because of the 32-bit word-
oriented M88000 memory bus architecture.
PLCC/CLCC EPROMs, providing 512KB (128K words) of storage.
Both EPROMs are necessary regardless of how much space is
actually occupied by the firmware, because of the 32-bit word-
oriented M88000 memory bus architecture.
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 EPROMs), is tested for an expected zero.
Thus, users are cautioned against modification of the EPROMs
unless re-checksum precautions are taken.
firmware entry, and the result (which includes a pre-calculated
checksum contained in the EPROMs), is tested for an expected zero.
Thus, users are cautioned against modification of the EPROMs
unless re-checksum precautions are taken.