On Fri, Jan 27, 2006 at 08:22:19AM +0100, Wouter van Ooijen wrote:
> No, IMHO there are places and times when a bootloader is appropriate,
> even if it can't fully protect itself. In a classroom for instance,
> where re-installing the bootloader can be a matter of seconds. But not
> when the students are supposed to work at home too.

Heck, I wrote a bootloader from scratch not too long ago to allow one
PIC to control an group of 64 smaller pics doing motor control.

Much easier, and less scary, to write a good heavilly tested bootloader
for the slave chips so I could mess around with the actual motor
controler algorithm all I wanted, confident that it would be easy to
reflash the memory of the slaves just by flipping a switch.

Well... That's the idea anyway, still screwed up twice with my
bootloader and had to reflash about 40 chips... But it was a good
thought!

Implementation wise I just put the bootloader in the first 512 bytes of
program memory and used org 0x200 as the first line of the slave code.
The interrupt vector at 0x04 or whatever was then set with goto 0x204
Worked just fine. I think there shouldn't really be much need for
transparency, even C code can be easilly relocated with all the
compilers I've heard of.

-- 
pete@petertodd.ca http://www.petertodd.ca
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