My 2 cents on bootstrap loaders. (fwd)

[peb@xxxxxxxxxxxxxxxxxx (Paul E. Bennett)]

> There has been a bit of talk here about putting a bootstrap loader into the
> f21 on chip rom. I'm crossing my fingers really hard that this happens. 
Lines: 43

Only if the right scheme happens. The question is how powerful should 
this be.

[%X]

> Anyway to get to the point. I think the minimum requirement for a boot
> strap is to load a fixed sized program into a fixed location at a fixed
> baudrate and then jumping to a fixed location to execute it. 

Problem is, with a fixed baudrate you would need to be sure that the other
end could handle it. What would it take to sense the baudrate and fix on 
that. Most eval boards I've used will do it. The RTX-EB did it with a soft 
UART. Shouldn't be any more difficult in hardware. Anyway, I  thought that 
the F21 boot was intended to be via the network interface.

> ...........................................................There also
> needs to be a way to disable the bootstrap so a normal reset can happen
> (such as testing for a break on the serial line).

I presume you mean after the boot-up. Probably some latch to be set and 
maintained so long as power remains on.

> Any extras such as memory peek/poke, variable baudrate, program length,
> program location, program execute address or feedback during loading can to
> done away with if rom size is an issue.
> So how much rom does it take to do a serial uart (input only), input say 1k
> bytes, stick them into memory and execute?
> I suspect not very much, it might even fit the current sized rom (but I've
> forgotten how big that is).
> Eddie,
> Edward Matejowsky - Queensland University of Technology (Brisbane, Australia)
> personal home page at http://www.ozemail.com.au/~eddiema/index.html
 
ROM size has been mentioned. I'm too lazy this morning to go back through 
articles. I wonder if a highly tested and verified Open Boot could be put
in place or is that too complex.
 

-- 
Paul E. Bennett ................... <peb@transcontech.co.uk>
Transport Control Technology Ltd.   <http://www.tcontec.demon.co.uk/>
+44 (0)117-9499861                  <enquiry@transcontech.co.uk>
Going Forth Safely