IBM 1410 ALD to FPGA – Punch Column Binary ALD anomaly

Came across something interesting today on Automatic Logic Diagram 13.50.04.1. It refers to unit “8” – which is for punch column binary – a special feature. An 8 character is just the 8 bit – odd parity. However, to decode unit 8 per the ALD one would have to have B 8 – and no check bit – even parity- which can never happen. So, if one were going to have the column binary feature installed, it would require an actual rework to change the input to one of the pins on ALD 13.50.04.1, coordinate 3A (11DJ02) from “+S E CH U SEL REG B BIT” to “+S E CH U SEL REG NOT B BIT”. So, without this rework, the machine would simply not decode unit 8 at all – perhaps intentionally. (Of course, on the generated version, this would be an easy fix, but for now I just left it as is.)

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