[OpenBIOS] Beginners How-To for DTS and OpenFirmware?

[Tarl Neustaedter]

On 2016-Nov-21 15:07 , Michael wrote:
> Thank you, I found this (and more) last week. The OLPC sites are the
> best for me:
>
> 1: http://wiki.laptop.org/go/Open_Firmware
> 2: http://wiki.laptop.org/go/Forth_Lessons
> 3: http://wiki.laptop.org/go/Cross_Compiling_Open_Firmware

[...]

Some history behind that...

Back in the dim, dark past (1980's), Mitch Bradley worked for Sun
Microsystems on system startup. At some point, he left to create a
startup (firmworks.com), and produced a forth kernel used for booting
SPARCs, which sun adopted for the sun4c models and later. They worked
together at producing an IEEE standard, IEEE 1275-1994.

For a long time, Sun and Firmworks exchanged source code (I think
actually mostly Firmworks to Sun, but formally listed as exchange).
During that period, several other companies produced systems based on an
OpenFirmware initialization (Motorola, Apple & IBM's PPC implementations
are the ones which come to mind). As I understand it, these were
entirely separate implementations based on the IEEE 1275 document.
Fujitsu based their systems on a SPARC core, and I believe based their
code on Sun's implementation.

Decades went by, and industry interest in OpenFirmware waned (mostly
because EFI came on the scene, and for all its faults, it did adopt most
of OpenFirmware's important concepts and the massive support from the PC
market meant it was going to prevail), so eventually Mitch shut down
Firmworks.

Mitch got a contract to help the One-Laptop project with their BIOS work
and eventually persuaded them to ditch the traditional PC bios and
instead use a forth-based initialization, based on Firmwork's
OpenFirmware implementation. There were a number of factors involved,
primarily being that they were tremendously prom-limited, and a forth
implementation can pack in more functionality per byte than ordinary
executable code can.

Since Mitch is the leading prophet of the OpenFirmware cult, he's made a
point of carefully documenting everything involving OpenFirmware on
One-Laptop. So anything you find under laptop.org is going to be the
most recent edition by the person who knows the most about the standard
and implementations.