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by phkamp
921 days ago
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It goes all the way back to Windows 3.11, where printer drivers often directly fiddled the Centronics parallel port themselves. The Centronics port is nominally one-way, but it didn't take long for people to realize you could use it for bidirectional communication, thanks to a self-test feature IBM built into the original PC's parallel port adapter, which everybody copied faithfully. The most famous use was probably "LapLink" which enabled fast file transfer via a special cable. Printers and their matching drivers used the bidirectional communication to provide mode detailed status information than the single "Paper Out" signal. And the rest as they say, is a parade of horribles |
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The most ‘fun’ of these was when Microsoft marketing came up with the “Plug and Play” (https://en.wikipedia.org/wiki/Legacy_Plug_and_Play), and the engineers had to implement it for this port.
So, you have a port designed so that writing anything to it prints a character, but you somehow have to figure out what (if anything) is attached to it without making a printer attached to it print anything, a CD Writer to write, a hard disk to lock up, etc, with each device possibly having its own devious way of doing two-way communication over that port (by the time Windows 95 came out, how to do that was more or less settled, but users still had tons of old hardware and/or older parallel ports that behaved slightly differently)
If not for the time pressure to ship something, I think it must have been fun to work in the Microsoft department developing that feature with hundreds of obscure parallel port devices.
And of course, it never worked perfectly. How could it? I know people who had a device that erroneously got detected as a tape drive, making ¿Windows NT 4? pop up some dialog for attaching it.