I worked with a guy who had one of those.  He was a rather fidgety individual, so it
always took him several tries to get it right.  :-)
________________________________________
From: cctalk-bounces at 
classiccmp.org [cctalk-bounces at 
classiccmp.org] On Behalf Of
feldman.r at 
comcast.net [feldman.r at 
comcast.net]
Sent: Wednesday, October 08, 2008 2:16 PM
To: cctalk at 
classiccmp.org
Subject: Re: Unusual software carriers.
 Message: 12
Date: Wed, 8 Oct 2008 01:00:44 +0100
From: "Pete Edwards" <stimpy.u.idiot at gmail.com>
Subject: Re: Unusual software carriers. (Was :Vinyl Data- Classic
 Computers ) 
<snip>
 Does anyone else remember 'Tomorrow's
World' in the UK transmitting software
via a flashing square in the bottom right of the TV picture? There was some
kind of photocell dongle that attached to the computer. Memory is vague -
did it plug into the tape input? I can't remember what the target system
was, possible several via the basic translater mentioned earlier in the
thread? No idea what the data rate was.
--
Pete Edwards 
My son had a Timex Ironman watch that you programmed by holding it up to a computer screen
that flashed the data to a sensor on the watch. It would not work on an LCD, only a CRT.
Bob