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11. Cables, extensions and adaptors

The only wires needed in a mouse cable are as follows: TxD and RxD for data transfer, RTS and/or DTR for power sources, and ground. Translated into pin numbers, they are:

            9-pin port     25-pin port
        TxD     3                2
        RxD     2                3
        RTS     7                4
        DTR     4               20
        Gnd     5                7

The above table may be of use if you wish to make adaptors between 9- and 25-pin plugs, or extension cables.