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Serial port on 486

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First post, by lilhoser

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Working with this 486 motherboard: https://www.elhvb.com/mboards/chicony/ch471b/ch-471b.html

It has two onboard 10-pin COM connectors, but my serial port has a 9-pin ribbon cable. I'm not sure of the history here but is there any easy way to rewire the serial cable to work with a 10-pin connector so my serial mouse works?

Reply 1 of 7, by dionb

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lilhoser wrote on 2021-01-17, 20:09:

Working with this 486 motherboard: https://www.elhvb.com/mboards/chicony/ch471b/ch-471b.html

It has two onboard 10-pin COM connectors, but my serial port has a 9-pin ribbon cable. I'm not sure of the history here but is there any easy way to rewire the serial cable to work with a 10-pin connector so my serial mouse works?

That link doesn't contain info about the serial ports, but almost certainly that 10th pin is NC, i.e. Not Connected. So your 9-wire cable should work fine. Have you tried it?

Reply 2 of 7, by lilhoser

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The 9-pin ribbon cable has a piece of plastic in the 10th pin female pin hole, so I'd have to bore that out somehow. Any suggestions?

Reply 3 of 7, by debs3759

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You can safely cut/break the 10th pin off the board, as it is not connected to anything. Just make sure you remove the correct pin.

See my graphics card database at www.gpuzoo.com
Constantly being worked on. Feel free to message me with any corrections or details of cards you would like me to research and add.

Reply 4 of 7, by lilhoser

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debs3759 wrote on 2021-01-17, 21:31:

You can safely cut/break the 10th pin off the board, as it is not connected to anything. Just make sure you remove the correct pin.

I am nervous about breaking motherboard pins, so I used a drill bit to drill out the 10th connector hole. Fits fine but mouse isn't working through it.

Reply 5 of 7, by dionb

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lilhoser wrote on 2021-01-17, 23:05:
debs3759 wrote on 2021-01-17, 21:31:

You can safely cut/break the 10th pin off the board, as it is not connected to anything. Just make sure you remove the correct pin.

I am nervous about breaking motherboard pins, so I used a drill bit to drill out the 10th connector hole. Fits fine but mouse isn't working through it.

- have you lined up pin 1 with cable and board?
- how are you testing the mouse? and what kind is it?

Generally ctmouse is the driver to use, with some Mouse Systems mice you need to specifiy ctmouse /m

Reply 6 of 7, by lilhoser

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yep pin 1 is aligned. using msinput\mouse.exe /f

hardware is an old logitech serial mouse

Reply 7 of 7, by quicknick

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There are two types of serial headers. Using a multimeter, check if you have GND on pin 5 at the DB9 connector. If not, your ribbon cable/DB9 is wired for the other type of header. Pretty easy to correct with a bit of soldering.

https://pinoutguide.com/Motherboard/rs232_hea … er_pinout.shtml