VT52s, VT61s lots of DEC and DG keyboards- return trip through Maine, MA, NY, PA, OH, IN to IL

[Jay Jaeger]

On 10/13/2015 12:02 AM, tony duell wrote:
> 
>>
>> Paul, if you come across any VT52s that have the built-in screen
>> printer could you take some pictures please.
>>
>> Has anyone ever seen one? I had an idea it used a silvered-paper and
>> burned it off? or am I mis-remembering.
> 
> I have one. Well, in a VT55, but that is a VT52 with a graph-plotting board, so
> I guess it counts :-)
> 
> It appears to be electrolytic. You have to keep the paper damp (there is a wick
> inside that you put water on. The paper goes between a helical electrode on
> a spinning drum and a straight strip, the latter being replaced when you fit a new
> roll of paper. Whether it is some chemical in the paper that changes colour, or metal
> depositied from the electrode I don't know (the former seems more likely). 
> 
> I have never got it to work. Whether that is due to electronic problems (that I can
> fix) or chemical problems with the old paper (which I can't) I don't yet know.
> 
> -tony
> 

I had a little Comprint printer in the 1970s/1980s that used something
sort of like this.  The paper was aluminum coated, thus conductive.  The
head was a high voltage electrode unit that burned away the aluminum
layer.  (I can't imagine any kind of deposition technology in that
era...).  The head flew back and forth really fast, doing one pixel-line
at a time.

JRJ