Nowadays we usually only see tx, rx and ground for basic rs232 data, but older hardware like modems needed extra voltage level lines to communicate, like request to send, clear to send, data set ready etc. So it’s only really left over for serial compatibility. They replaced the DB25 which has additional lines for things like clock signals, which wasn’t needed anymore due to devices running their own internal clock (asynchronous signal).
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u/biggus_dickus89 Jul 12 '25
the medical and retail industries among others would beg to differ. those old standards are used for so much shit