A couple of errors in the IBM 1410 System Fundamentals manual

For starters, I should say that the IBM Field Engineering Instructional materials, which I relied on heavily when creating my IBM 1410 Simulator software are excellent, especially considering these documents were typeset in more than a decade before anyone had heard of a word processor.

Nonetheless, I stumbled into two errors in the IBM 1410 System Fundamentals manual, S23-2589, this week. Both are instances where the output signals from gates are different from what is shown in the document.

The first one I ran into was the first Single Shot that I came across in the diagrams, SMS card type DHE, part number 370262. The timing diagram shown in figure 110, page 93 of the manual shows a negative going input pulse triggering a positive going output pulse. An analysis of the electronics in the first of two SMS card manuals (which have no number) and the use of this card in an ALD,, makes it apparent that a negative going incoming pulse creates a negative going output pulse. (This was implemented in my FPGA VHDL generation by triggering a counter on the leading negative going input pulse, which then counts down to 0.)

The other error applies to card type DFZ (and its companion, DGA), which I ran into on ALD page The timing diagram in figure 107 on page 92 of the System Fundamentals manual shows NAND logic: If both inputs are high, the output goes negative. However, analysis of the circuit for DFZ, part number 370241 makes it apparent that it is actually NOR positive logic: If either input is high (approximately 0v), then the output is low. Only if both inputs are low (negative voltage) is the output voltage high. This was “sussed out” by looking at the intended logic on the ILD.

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