A lot of iron and steel foundries in the UK had a particular model of spectrometer built in the 1960s for carrying out analyses of metal samples. This spectrometer had an option of a hard-wired electric typewriter (not an IBM Selectric, a Remington or similar) that would print out the results of an analysis in a simple table. This was before Centronics printers were readily available. Back in the early 80s I worked with a consulting metallurgist to add a box to tap into the signals from the analyser to the typewriter and present them to a parallel-port interface so they could be read by a desktop computer. From memory the drive signals were at 24V with some weird pulse combinations for shifts, code pages etc. that we decoded by trial and error -- the company making the analysers wouldn't hand out the information and we couldn't mess with their internals since they were covered by long-term maintenance agreements (decades and more, these were very expensive bits of kit). We got the interface to work and the foundries were very happy to pay us to get the information out in digital for eventually supporting ISO9000 chain-of-custody certification which was necessary given that some of the places that used these analysers were making single large castings for paper-making machinery worth a million bucks a pop.