[E3-hacking] PBL & running arbitrary code

[Ralph Corderoy]

Hi David,

> > Where is the E2 GBP 20 now?  I think the E3's down to GBP 70 at
> > Carphone Warehouse.  The E2's still worth playing with though,
> > especially if you want to end up with more than one device.
> 
> Froogle reckons the cheapest is 27.99 from Ligo Electronics, but I've
> seen them in my local ASDA and I'll need to compare the price. Now the
> E3's out, they may be shifting the E2s cheap.

They've been GBP30 at Comet, Asda, and Sainsbury's since sometime in
2004.

> (I'm attracted to the E2 because they're reasonably capable devices
> and they're so cheap that I can justify buying one on a whim. The E3
> is a lot nicer, but unfortunately, more expensive than I like to spend
> on a toy.)

And cheap enough to buy more than one if you'd like a phone, intercom,
and multi-media controller in more than one room of the house.

> > Request 05 checks the destination addresses.  All the bytes
> > overwritten must be in the range 0x40000..0x7fffff inclusive,
> > 7936KiB.  I think the stack descends from 0x1ba00.
> 
> Meh. Not very useful. I take it the boot flash chip is mapped at 0 on
> reset? Looking at the processor's datasheet, that would seem to be
> logical.

It is, but is later moved out of there and RAM's put in its place.

> > Although with JTAG it should be possible to put a little EXP-port
> > downloader into RAM, run it, that pulls down a bootloader which in
> > turn is happy to run the code in Smart Media card inserted in the
> > side of the E2 which would avoid having to flash during development.
> 
> Unfortunately the E2 doesn't have a SMC card reader (as far as I know);

Take a look at en4rab's page linked to from my E2 one, especially the
image on that page.

    http://www.en4rab.dsl.pipex.com/

He labels a `SD card slot'.  Amstrad sell SmartMedia cards as
accessories for the E2.

    http://www.amstrad.com/emp_accessories.html

    Smart Media is digital solid state (no moving parts) memory, and is
    used as a data storage medium in items such as digital cameras. It
    enables the user to add to the existing memory of certain digital
    devices. By inserting a Smart Media card in to the side of the
    e-mailerplus, the user can store more email, fax and VoiceMail
    messages for later retrieval or archiving. Received and sent
    messages actioned whilst the smart media card is inserted will
    automatically be stored on the Smart Media card instead of the
    internal memory of the e-mailerplus. 

The slot is on the side of the casing.  It's just a thin slot with no
labelling IIRC.

> it has a Smart Card reader, but you don't get a lot of data onto one of
> those.

Not that slot, another one.

Cheers,


Ralph.