Other Devices

Plotters

Other than the overprinting that could be done on a line printer (mentioned earlier), the only true way to draw objects was with a plotter. These devices used a pen (or a set of pens in different colors) to make line drawings. There were two usual types – flatbed plotters and drum plotters.

Flatbed plotters had a fixed size piece of paper. You would instruct the mechanism to move to a particular X-Y spot, then instruct the pen to lower to the paper, then instruct the mechanism move to a different X-Y coordinate. The largest flatbed plotter I saw was at the design center for Ford Motor Company in Dearborn, MI. They could draw entire body panels with it.

Drum plotters used a metal roll that carried the paper. The Y-axis was across the roll, and the drum rotated to position the pen at the appropriate X-axis. The length of the paper roll was relatively unlimited, but a final dimension of 2’ (across the roll) and 3’ of paper was typical.

On one occasion the university borrowed a “pin plotter” which could make three dimensional “shapes”. It had pressed boards about 2’x2’ in size with an X-Y mechanism underneath that carried a spool of copper wire. You would instruct the machine to go to a particular X-Y spot underneath, then instruct the spool to unwind Z inches of wire straight up to pierce the board. The machine automatically added enough wire to completely pierce the board and then would cut off the wire when the end of the wire was at the appropriate X-Y-Z spot on the shape you were plotting. There were limitations, both on the height that you could go above the board (or the wire would begin to bend) and how close together you could put two wires (or risk weakening the board by having too many holes in it). This may have been the first instance of a 3D plotter.

Console

A sometimes forgotten peripheral was the system console. This was typically a variation of an IBM Selectric Typewriter that was used by the main computer operator. But it could be used on a very selective basis for inputting key information. Typical uses were for things like the starting check number that was going to be printed so the program could keep track of the check number generated for each employee that pay period, or a special month-end date for accounting purposes. In COBOL, there were two special instructions “DISPLAY ___ UPON CONSOLE” and “ACCEPT ___ FROM CONSOLE”. So the program would first DISPLAY what it wanted to operator to enter (e.g. DISPLAY “PLEASE ENTER STARTING CHECK NUMBER AS NNNNN UPON CONSOLE”) followed by “ACCEPT STARTING-CHECK-NUMBER FROM CONSOLE”. When computers only ran one or a few programs at once, this was a reasonable solution.