[E3-hacking] PBL & running arbitrary code

[David Given]

I recently found the Emailer Recycling page, and read the documentation
there; it all looks highly intriguing, and I'm thinking of getting an E2
or E3, mainly as a toy. Amstrad have always been good at making hackable
hardware --- I own a NC200, possibly the nicest Z80 laptop ever made,
and have successfully run my own code on it. Still haven't managed to
finish that CP/M port, though...

Does anyone know if it's possible to use PBL to download and run
arbitrary code on the device?

Directive 05 would seem to allow data to be written to memory, but there
doesn't seem to be any way of getting it to be executed. Does anyone
know of such a thing? Would 05 allow you to overwrite PBL's stack (the
dodgy way of doing this?) What about well-known PBL variables? And what
does 07 do?

(I suppose the easiest way of running your own code is to write it into
the flash and then do a normal boot, but I'd rather not brick it
immediately. Heaven forbid, the standard software might turn out to be
useful.)

-- 
David Given <dg@cowlark.com>