In your opinion, I could solve with this one? https://www.amazon.it/Kalea-Informatique-cont … F1073DE2E585ECF

I'm not sure if it works on ms-dos

lutz79 wrote on 2020-03-14, 17:53:

Hello guys! I need your help! I have a 486DX4-100 without a serial port, and i can't use any mouse because the motherboard don't […]
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Hello guys! I need your help!
I have a 486DX4-100 without a serial port, and i can't use any mouse because the motherboard don't have any ps/2 ports, but only COM1 and COM2 connectors with 10 pins.
I have purchased this one from Amazon: https://www.amazon.it/gp/product/B001Y1F0HW/r … 0?ie=UTF8&psc=1

The problem is that the driver (mouse.sys and mouse.com) dont' work. Obtain the error message "mouse not found". I have tried different drivers, but the problem is the same. In the BIOS setup, both com1 and com2 are enables. On my 8088, also without mouse connected, the driver works regularly (with com1 integrated on motherboard).

I believe that the serial connectors are all the same, but I'm not sure. In your opinion, could there be incompatibility issues with an XT motherboard? how could I solve the problem?

Thanks!

Not all motherboard COM port headers are wired the same. The one from Startech may work on some boards but not all. If you know the exact make and model of the 486DX board tell us OR attach a very clear picture of the motherboard. That way we can help find the COM header pinout and maybe help you to to Mod or re-wire your new com cable.

Thanks for your reply! This is my board!

Ahh ! The infamous PcChips m919 v3.4 or Amptron DX9700 with no onboard cache. That uses the standard PcChips com port pinout. I will look it up and and get back to you.

Thanks!

Ok so there are two standard motherboard pin outs for COM ports, and probably a few proprietary ones. The standard ones are AT/EVEREX type or DTK/INTEL type, the way to check is from pin 5 or pin 9 on the header. If pin 5 is Ground then AT/Everex, if pin 9 is ground then DTK/INTEL. The PcChips m919 v3.4 (or at least my board) has pin 5 as ground just like early Asus and Gigabyte so is AT/Everex. To check your COM port dongle you need to check if pin 5 on the the header connection is connected to pin 5 or pin 3 of DB9.
if connected to pin 5 then it will work with AT/Everex header, if to pin 3 then DTK/Intel header wired. To verify if DTK/Intel type and not proprietary if you discover Pin 5 on header connector is to pin 3 on DB9: check pin 9 on header connector to pin 5 on DB9, it should be 0 ohms. Anything else is proprietary and will need further checking.
Note: Pin 1 on the dongle header connector always goes to Pin 1 on the DB9, no matter which type.

1RS232 Motherboard header pinout ( AT/EVEREX )
2IDC internal
3 (newer)
4AT/EVEREX Signal Name	Description
5pin number
6
7header pin				cable pin
81 	DCD 	Data Carrier Detect 	1
92 	RXD 	Receive Data 		2
103 	TXD 	Transmit Data 		3
114 	DTR 	Data Terminal Ready 	4
125 	GND 	System Ground 		5
136 	DSR 	Data Set Ready 		6
147 	RTS 	Request to Send 	7
158 	CTS 	Clear to Send 		8
169 	RI 	Ring Indicator 		9
17
18
19RS232 Motherboard header pinout ( DTK/INTEL )
20IDC internal
21(older)
22 
23DTK/INTEL Signal Name Description 	
24pin number
25
26Header pin				cable pin
271 	DCD 	Data Carrier Detect 	1
282 	DSR 	Data Set Ready 		6
293 	RXD 	Receive Data 		2
304 	RTS 	Request to Send 	7
315 	TXD	Transmit Data 		3
326 	CTS	Clear to Send 		8
337 	DTR	Data Terminal Ready 	4
348 	RI	Ring Indicator 		9
359 	GND	System Ground 		5
36
37Pin 10 removed in connector.

EDIT: added extra info and corrected my grammar

Thanks for your reply! Very kind and exhaustive! A question: how do i know if pin 5 is ground? can I use a multimeter?

lutz79 wrote on 2020-03-15, 13:11:

Thanks for your reply! Very kind and exhaustive! A question: how do i know if pin 5 is ground? can I use a multimeter?

Yes, that would be the way to know it.

could you explain me how? thanks!

lutz79 wrote on 2020-03-15, 17:06:

could you explain me how? thanks!

Locate a jumper on the motherboard which has the GND marked. Usually the speaker has + and -, in this case GND is - and with the multimeter test if there is continuity between this GND point and any other point you want to test. The resistance between both points should be "zero Ohms".

I use a board mount hole with the solder ring around as Ground all the time for testing, touch Negative lead from DVM there. Then find pin 5 of the board COM header and check with positive lead from DVM and verify 0 ohms. For the COM dongle use a needle and stick it in Pin1 of the black board connector, touch it with one DVM lead and touch Pin 1 on the DB9 connector with other DVM lead, it should be 0 ohms or close. Next move needle to pin 5 on the black board connector and touch it and touch pin 5 on the DB9 connector, if zero ohms then you have to proper dongle. If not 0 ohms you have the wrong dongle.

Ok, i have verified the pins on the motherboard and the pins on dongle.
The GND on the com port on the motherboard, is on the pin 5. Also on the dongle the GND is on the pin 5.

Then, I think it's a connector AT/EVEREX and my dongle should be compatible. Why do you think it doesn't work?

Thanks!!
P.S. I have a Serial to PS2 adapter, because i don't have a serial mouse. Only PS2 (with wheel).

This is my situation!

lutz79 wrote on 2020-03-17, 14:35:

P.S. I have a Serial to PS2 adapter, because i don't have a serial mouse. Only PS2 (with wheel).

Does the sticker on the bottom of the mouse say anything about 'serial compatibility' ?

I noticed that the serial-ps2 adapter is not configured correctly. The GND should be on pin 3, and instead it is on pin 4. I think the problem stems from the faulty adapter, or configured upside down. I will buy another adapter or directly a serial mouse.

? Please, post a photo of that adapter...

https://www.amazon.it/gp/product/B00HHD296G/r … 0?ie=UTF8&psc=1

Is that!

I have see that the PS2 female pinout, in default, has the GND on connector 3. But this adapter has the GND on connector 4! I believe that this is a problem...!

Are you sure that you use the 'right' ground position on the "DB9" female side of that adapter when you are measuring ?