PMON is a freeware ROM-monitor developed for early LSI Logic MIPS R3000 evaluation boards. Since its creation, PMON has become a very common firmware for MIPS evaluation boards and development systems.
For information on PMON, visit Phil Bunce's (PMON's designer) website at http://www.carmel.com/pmon .
The original PMON code base is rather old now, supports relatively few boards and is not being actively worked on by a single project team. PMON 2000 has become the inofficial successor of PMON.
PMON comes with excellent documentation in HTML.
The latest PMON source, modifyed by Algorithmics is available as pmonsrc-20011116.tar.gz. It contains support for much more boards, R4000-style exeptions, and comes with more recent build system (for GNU make).
Linksys WRT54G and Asus WL-300g, a WiFi 802.11g AccessPoints (both BCM47XX based) uses PMON version 5.3.22 as a Linux bootloader. PMON port to the BCM47XX is available from the GPL'ed sourcecode for this devices.