Accounting machines, the IBM 1403, and why printers standardized on 132 columns

Re:Accounting machines, the IBM 1403, and why printers stand... by kens on Tuesday January 22, 2019 @08:38PM (#18974896)

I've heard the breaking chain story many times, but I suspect it's mostly an urban legend. At least on the 1403, the hammers can't all fire at once. The chain and hammers have different spacings so only one hammer is lined up at a time, 11.1μs apart; the worst you could do is fire every third hammer in rapid sequence. For reference, a standard chain sequence is 1234567890#@/STUVWXYZ‡,%JKLMNOPQR-$*ABCDEFGHI+.¤

The 1403's print chain is pretty complicated to understand, so I built an animation: http://righto.com/ibm1401/printchain.html

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Re:Accounting machines, the IBM 1403, and why printers stand... by abraae on Tuesday January 22, 2019 @09:18PM (#18975090)

I used to work at IBM as a CSR (maybe we were CEs back then?) fixing 1403s and other mainframe boxes.

Man it would have been so useful to have your fantastic animation back then. I came on the scene too late to ever get any formal training on 1403, so I ended up learning most of it the hard way. I don't think I ever fully understood the hammer mechanics as you have explained it.

An animation is truely worth 1000 words.

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