Line Printer

This is a large Barrel Printer used on EE KDF Computers. The barrel consisted of several rings containing the fonts that were threaded on a long keyed shaft to make up 160 columns. The purpose was to enable highly used columns to be replaced discreetly when worn to the limit. I believe the rings were 10 characters wide. Beautifully engineered and highly expensive! The barrel ran horizontally and was turned by a toothed belt with a corresponding 160 actuators mounted below it. The paper was driven between barrel and actuators by tractors engaging with the perforations at the edges. On the end of the barrel sat a glass disc with 160 graticules for characters and a couple of other for rotation timing engraved on it. All the printers timings were driven from the output from small light bulb and photo sensor either side of the graticules. If you didn't get that in good order and dust free, you never got to sleep on the nightshift! The electronics, timing settings and regular maintenence were one of the most demanding parts of looking after a KDF Mainframe suite (KDF9 in my case) . Some of the electronics were mounted within the printer but most was contained in a seperate Controller cabinet nearby. This contained the clever stuff like the i/f to the mainframe, data buffers,data assimilator etc. As ever, all the electronic components were discreet parts mounted on pcbs and with cicuit diagrams down to Transistor/Resistor level. I suspect the training on both the mechanics and electronics took as long than modern Enterpise systems nowadays. The engineering and build was incredible, when I was last involved they we around 10 years old and went on for a few years after that. With spares availability I believe they could have been running now.