Everything dmux said, adding the fact that Forth can be implemented by extremely simple and compact code, think of it as the smalltalk of the embedded world (For instance Apple bios - open firmware - give the user a Forth REPL)
That same Open Firmware Forth system [1], which was developed by Mitch Bradley [2], was not only in the PowerPC Mac bios, but it was originally used for the SparcStation boot roms, and eventually in the OLPC, and it was even an IEEE Standard 1275-1994!
In fact: the Open Firmware boot loader and plug-in card firmware interface technology, commonly used by both Sun and Apple, is the only firmware standard in existence to ♫ have its own theme song ♫ [3] !!!
: OpenFirmwareSong ( 🎸- ♬ )
\ By Mitch Bradley.
\ Sung to the tune of "The Flintstones".
𝄞
." Firmware" cr
." Open Firmware" cr
." It's the appropriate technology," cr
." Features" cr
." FCode booting" cr
." Hierarchical DevInfo tree." cr
." Hack Forth" cr
." Using Emacs on the keys," cr
." Save in" cr
." NVRAM if you please." cr
𝄒 cr
." With your" cr
." Open Firmware" cr
." You can fix the bugs in no time" cr
." Bring the kernel up in no time" cr
." We'll have an FCode time!" cr
𝄒 cr
\ Thank you and good night!
reboot
;
Open Firmware is an amazing piece of software. Mitch's Forth Lessons on the OLPC wiki are a great resource too, especially if you have an OLPC XO that you can boot to the firmware prompt. http://wiki.laptop.org/go/Forth_Lessons
OpenFirmware is one of the main inspirations for the design of Snabb Switch too. I was impressed that Mitch writes his own drivers faster than most people can integrate off-the-shelf ones. He sets a great example of getting more done by making a habit of self-sufficiency instead of accumulating ever more dependencies and keeping them up to date.
I worked with Mitch on "bringup" of the OLPC 1.5 hardware and got to see him doing amazing things. The best was when he needed to initialize the memory controller to make RAM available and so he flashed a small Forth system that could run strictly within cache and then connected to that with a serial port and poked the memory controller registers until he had the RAM working. Made an impression on me :-).
