Open Firmware, was Re: Bootstrappable language

[Dave McGuire]

On Dec 11, 2008, at 10:42 AM, Paul Koning wrote:
> Another place where Forth has been used: several popular workstations
> use it for their bootloaders.  Sun does (or did) and I think Apple
> does too.  At least I once got an "ok" prompt when I powered up a very
> confused Power Mac... and it answered like Forth interactive mode.

   This is correct...it's called Open Firmware, and it has been the  
ROM-based boot facility (and some other neat stuff) in all SPARC- 
based Sun systems from the SPARCstation-1 on up to the current  
hardware, all Apple PCI-based PPC systems, and many IBM POWER-based  
(RS/6000) systems.  Sun calls it OpenBoot.  The OLPC XO-1 laptop  
(based on an AMD x86 implementation) also has Open Firmware, and  
probably other machines as well.

   Open Firmware is an IEEE standard (1275) and can be implemented on  
just about anything. It is well documented, portable, well behaved,  
and used to great success.  In the face of these facts, one wonders  
why things like EFI are brought into existence.

   What seems to surprise most people is that this makes Forth one of  
the most widely-deployed languages in modern computing.  I recently  
had a conversation with an otherwise extremely clueful guy who even  
has a background in embedded systems, who thought Forth was  
completely dead.  He was shocked to learn that the Mac he was typing  
on had a Forth implementation in flash.

   As you observed, it is indeed Forth.  It's an extremely powerful  
and well-thought-out system that allows expansion cards to contain  
machine-independent code ("FCode", Forth bytecode) in ROM or flash  
that implements initialization and diagnostic routines, bootstrap  
code, and OS-accessible/-usable device drivers.

   If you've ever noticed the flash chip on Sbus cards...that's  
what's in there.  Some PCI cards have it as well; the world would be  
a much happier place if all of them did.

   So, one other implication here is that any old SPARCstation  
sitting in a closet makes a great Forth hack machine.

          -Dave
>


-- 
Dave McGuire
Port Charlotte, FL