On 7/27/06, Jim Isbell, W5JAI <jim.isbell at gmail.com> wrote:
The worst printer of all came before the computer.
The Datafax. It
used paper sensitive to an electric discharge (spark) and could send
signatures by wire. The paper was held to a metal drum with tensioned
springs and a stylus hovered just above the paper and an electrical
discharge jumped from the stylus to the drum through the paper. I have
a stack of them in my garage.
I worked with a shades-of-grey spak printer attached to a PDP-11,
circa 1986 - the paper was multi-layered, and the intensity of the
spark ablated the paper to different depths, revealing darker and
darker shades.
It was fussy and, while it _did_ give visibly different shades, didn't
seem like it was worth all the effort. I think the design was
originally used as a SONAR hardcopy device (we were using it to
display ultrasound scan data for industrial parts inspection).
-ethan