An Improvement in the Art of Chain Printing 4003

Charlie Gibbs

That sounds like how one model of the Dataproducts drum printer did it. A spinning drum with the entire character set for each of the columns. The small drum was 64 characters around, the bigger one had 96. A full width ribbon ran over the drum, following the same path as the paper through the printing area. Next, the paper is pulled up vertically from the supply box, past the print area, over the top of the printer, and stacked in the back. The hammers sat behind the paper, and when fired, pushed the paper into the ribbon and the whole mess mashed into the selected character. There was on hammer for every other print column. The entire hammerbank shifted left or right to do the even or odd characters. Naturally it was nicknamed "The Shaker".

In the drum series printers, the hammers came in a module of 4, were flat conducting metal plates supported on springy posts that also carried the fire pulse into the hammer. The face that actually struck the paper was on an upper corner. Each hammer pivoted out of it's slot between the magnets that made up the rest of the buttembly. As I recall, the supply to the hammers was around 50 volts, backed up by several capacitors, each the size of a soda can.

These printers could fire all hammers at once without self destruction. Some of the adjustments required a single character. Usually "E" was best because all corners of the character were printed, problems were seen as one of the corners that was uneven. "Flight time" was the principal hammer adjustment, in this system changing the backstop position.

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