[E3-hacking] E1

David Given dg at cowlark.com
Wed Oct 1 23:01:42 BST 2008

David Given wrote:
> I'll try hooking up a
> voltmeter and seeing what the E1's TX is producing.

With PBL running, I'm reading about -9V at the E1's Tx pin and +9V at
CTS and DSR. When PBL's not running it leaves CTS and DSR low. This
sounds like a real serial port to *me*.

But nothing seems to come out. I need a scope.

It might be waiting for some sort of passkey, although this seems a
little unlikely. If so, though, our only options are either hope that
some nice person from Amstrad tells us what it is, or else to build a
JTAG adaptor and extract the ROM...

Incidentally, I took another peek inside looking for jumpers, and I did
notice two unpopulated 0.1" headers: one is a 16-pin one, but next to it
is a 20-pin one with a box around it. It's not labelled other than as
JB1, but it could very well be a standard JTAG header. I would *not* be
keen on soldering pins to that, though, particularly if I wanted them to
be in a straight line.

BTW, any recommendations on JTAG hardware? It occurs to me that now I've
fried the UART on the E2, I might as well have a go with attaching JTAG
pins --- I can't make it any less useful than it is now.

┌─── dg@cowlark.com ───── http://www.cowlark.com ─────
│ "...it's not that well-designed GUI's are rare, it's just that the
│ three-armed users GUI's are designed for are rare." --- Mike Uhl on
│ a.f.c

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