I remember seeing these in stores back then, I wondered what happened to them.

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=2168462333&category=3638

i remember those.you could never get a true black because of the need to keep beam current above a certain level for it to work.
fussy and unstable.most are probably in the landfill now
i have 2 and all i can say is only an idiot would have marketed these.