Chain printers like this were amazing to watch, the chain had to move amazingly fast and could break ... I worked with a Burroughs mainframe, we were always cau

Chain printers like this were amazing to watch, the chain had to move amazingly fast and could break ... I worked with a Burroughs mainframe, we were always cautioned never to stand either side of the printer, because reputedly if the chain broke it could fly out the side and embed itself in the wall (never actually happened to us) On some printers you could change chains for particular print jobs - when we printed some jobs we'd load up a chain with just digits on it (so the printer could print an entire line while the chain moved 10 locations rather than 48 locations - theoretically 5 times faster. Page layout was done with a loop of paper tape N positions long (that matched the number of lines on a page) and 10 widem each one of 10 horizontal holes corresponded to one of the fortran carriage control commands "1" meant "skip until there's a hole in position 1 on the tape" - you'd change to a special loop when printing labels for example, or for different sized paper - if you made a loop and were stupid enough not to have a hole in each horizontal position at least once around a loop skipping to that position would result in a "page throw" fanfold paper would exit the printer horizontally until it hit the wall and would continue to do so until you ran out or someone noticed