Serial port confusion

So there is an IDC header (two rows of pins) on the motherboard of one of my machines for a serial port. To make use of this, I need an IDC – DB9 adapter. It turns out these come in two flavors, depending on whether they’re aligned based on pin number of physical layout. Examples of each kind are here and here. Here is the pin numbering for each of the connectors:

IDC10:
1 3 5 7 9
2 4 6 8 10

DB9:
1 2 3 4 5
6 7 8 9

Wiring diagrams for each kind of alignment:

Physical alignment (aka DTK):

IDC10 DB9
1 1
2 6
3 2
4 7
5 3
6 8
7 4
8 9
9 5

One-to-one pin number alignment (aka EVEREX/APEX10):

IDC10 DB9
1 1
2 2
3 3
4 4
5 5
6 6
7 7
8 8
9 9

Other pages that discuss this issue are here, and here.

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