https://www.minuszerodegrees.net/manuals/AST_Advantage_Users_Manual.pdf
Page 100
In this case, the printer uses SRTS (Secondary Request To
Send, pin 19) instead of pin 4 (RTS); apart from that
exception, Figure 8-3 follows the ideal DTE input and
sequence rules.
The advantage of the interface shown in Figure 8-3 is that
every pin is driven by its functional counterpart on the other
side of the interface; the functionally related signal pairs
include DTR/DSR, RTS/CTS, and TxD/RxD. This should also
hold true for the interface you design.
So... all you dilettantes idn't bother about the odd pinout of the DB25
cereal port on the Model 90, even MAJ Tom doubted my sanity...
It's not an exact match, but it suggests why IBM pinned it like that.
If MAJ Tom doesn't stop this habit of -ASS U ME- ing he knows more than
me [you gotta work at it...] more things may be memory holed.
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