1970's digitizer tablets

From: Tony Duell <ard_at_p850ug1.demon.co.uk>
Date: Tue Jul 15 16:03:00 2003

> > In 1983, I wanted a digitizer for blackboards. As a "proof of
> > concept", I attached a one foot long piece of clear plastic (a
> > ruler) to the shaft of a potentiometer. At the other end of it
> > I attached another potentiometer, with another foot long piece
> > of clear plastic attached to the shaft of that one. That made
> > for an upper arm hinged at the edge of the board with a
> > potentiometer, and a forearm hinged at the end of that with a
> > potentiometer at the "elbow".
>
> There was a very similar device around in the early 1980s; I can't
> remember what it was called but it hooked up to one of the machines at
> the college I worked in then, so it must have been for a BBC Micro
> (around 1983) or an Apple ][ or PET (about 1982). Its operational area
> was about an A4 sheet.

One of the projects in the first Fischer Technik Robotics kit was a
digitiser like that. The kit contained 2 motors, an electromagnet, 3
lamps, 8 switches, 2 potentiometers and various mechanical bits. You used
the 2 pots in a double-jointed arm (as above) to cover an area about the
size of an A4 sheet.

Other projects included :

A plotter (of a strange design, in that it worked in polar coordinates,
ther was an arm that could be rotated by one of the motors (using a pot
for feedback) and the pen carriage ran along said arm (using the other
motor and pot)

2 simple robot arms, one of which was designed to play the Tower of
Hanoi. This was the thing I demonstrated at the 1997 HPCC conference.

The kit dod not include any form of computer interface. I think you could
buy them for the IBM PC, Apple ][, etc. But not for the TRS-80s (which
were the machins I had at the time). I built my own, initially for the
Model 1, and then later for the HP48 calculator....

-tony
Received on Tue Jul 15 2003 - 16:03:00 BST