mmon: MIPS VR4300 Mini-monitor
Copyright 1996, 2003 Eric Smith <eric@brouhaha.com>
http://www.brouhaha.com/~eric/software/mmon/

mmon is a tiny monitor program for the VR4300 MIPS processor.  It can
operate with NO working RAM, using only the processor registers, so it
can be useful for hardware bringup, including testing a RAM controller.

With minor changes, mmon should be usable on other 64-bit MIPS processors.

mmon was originally assembled using the SDE-MIPS tool chain from Algorithmics.
This might still be available from MIPS, but it should be relatively easy
to convert to the GNU toolchain.

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This program is free software; you can redistribute it and/or modify it
under the terms of the GNU General Public License version 2 as published
by the Free Software Foundation.  Note that permission is not granted to
redistribute this program under the terms of any later version of the
General Public License.

This program is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
General Public License for more details.

You should have received a copy of the GNU General Public License along
with this program; if not, write to the Free Software Foundation, Inc.,
675 Mass Ave, Cambridge, MA 02139, USA.

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New in this version:
	On our target hardware, same DRAM is aliased between a0000000 and
	bfc00000.  Data section starts at a0000010 to allow room for the
	four instructions of the reset exception handler.  Data section must
	end before a0000200, so size of data section must be <= 496 bytes

Commands are:

db <addr1> [<addr2>]	dump memory bytes from addr1 to addr2 (non-inclusive)
dh <addr1> [<addr2>]	dump memory half-words (16-bit)
dw <addr1> [<addr2>]	dump memory words (32-bit)

sb <addr> <data>...	store one byte of data to address
sh <addr> <data>...	store one half-word (16-bit) of data to address
sw <addr> <data>...	store one word (32-bit) of data to address
swl <addr> <data>	store word left
swr <addr> <data>	store word right

fb <addr1> <addr2> <data>  fill bytes of memory
fh <addr1> <addr2> <data>  fill half-words
fw <addr1> <addr2> <data>  fill words

l                          load S-records

g <addr>                   go (start execution at address)

Addresses and data must be given in hexadecimal.
Everything (including hex digits 'a'..'f') must be in lower case.
There is no error checking of any kind.
If you give an invalid address you will probably get an exception which
will hang and you will have to press the reset button.
A lengthy dump can be interrupted by sending any character.