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Serial Mice

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fatwizard

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Sep 28, 2012
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Indiana, USA
I acquired an AT tower case a while back, and I just got around to cleaning it up and building a system with it. I had a socket 5 motherboard with a Pentium 90 already setup for this project. As I am installing Windows 95 I notice there is no mouse pointer. I was using the onboard serial ports, so I check the ribbon cable and header. I verify that the ribbon cable is plugged into the header on the motherboard the correct way. I checked CMOS that the serial ports are enabled. I toggled them in CMOS, off then back on. No soap. I have several serial mice which work fine, but none are detected with this setup. I finally pulled the motherboard and substituted another very similar motherboard. Same result with a different motherboard.

This time I tested the built in serial ports with Checkit and a loopback connector. COM1 and COM2 pass with flying colors. I tried a serial expansion card, and the mouse is detected properly using that. I put a socket 7 board on the bench and found it would not detect a serial mouse on the onboard ports either. I have done this sort of thing in the past more times than I can count, and I am flummoxed that it now doesn't work.

I have a feeling I am having a senior moment with this, like I am forgetting some step that I used to remember without trying.

Maybe someone can jog an old man's memory.
 
I wonder if your mouse is working. You can usually check it pretty easily by using a terminal program set to 1200-n-8-1.

But yeah, with Win95, your mouse should be discovered automatically.
 
Chuck(G) said:
I wonder if your mouse is working.
Click to expand...
Sure appears to be the case:

fatwizard said:
I have several serial mice which work fine, but none are detected with this setup. I finally pulled the motherboard and substituted another very similar motherboard. Same result with a different motherboard.

I tried a serial expansion card, and the mouse is detected properly using that.
Click to expand...
Does CheckIt report COM1=3F8h and COM2=2F8h on the boards that don't detect the mouse?
 
It is also a good idea to test using a DOS mouse driver and some DOS program that uses the mouse. If that works, then Windows 95 is probably doing something screwy.

Check to see if Windows 95 shows any kind of IRQ conflict, but it might not tell you. I recall running in to a similar problem once between a PS/2 mouse port and an ISA SCSI adapter.

It is also possible that Windows 95 can get in such a state that it won't auto detect. Perhaps some other driver is confusing it. If that happens, you may need to re-run the Add New Hardware wizard.

Also, is this a generic serial mouse? If there is anything special about it (extra buttons, wheels, blinky light, etc.) you may need to install a driver specific to this mouse, or use the Add New Hardware or Device Manager to force a generic mouse driver.
 
krebizfan said:
The serial port might not be putting out enough power for a mouse.
Click to expand...

This would make sense, but I am SURE I have used serial mice with this very board in the past. These early AT Pentium boards had no PS2 mouse port and I always just used serial mice and the built in serial ports. That's how I did it when I was building these things brand new for customers.

I did resort to testing with a DOS mouse driver, and the mice all work if I use a serial expansion card, but not the built in ports. Checkit reports the standard I/O and interrupt for COM1 and COM2.

This is so weird. I feel like I am losing my mind.
 
You many need to enable driver manually. Go to Control Panel>Add New Hardware, and select the generic driver from the 'Standard mouse types' category.
 
Chuck(G) said:
You many need to enable driver manually. Go to Control Panel>Add New Hardware, and select the generic driver from the 'Standard mouse types' category.
Click to expand...
???

But it doesn't even work from DOS which uses a manually loaded driver.

The problem is pre-Windows.
 
Let's summarize.

1) The mouse works with a serial expansion card.
2) The mouse doesn't work with the integrated (on board) serial ports. The same result obtains with another similar board.
3) The OP is certain that the mouse once worked on this board.

My questions:

1) Have you tried testing the board using loop-back connectiors?
2) Can you send and receive using the on-board serial port?
3) With the mouse connected and nothing happening, what's the voltage between TXD and ground?
4) Are the serial ports complete? That is, do they have the required handshaking lines? (CTS/RTS DSR, etc.) A serial mouse derives its power from these lines.

My suspicions:

1) if the serial port connector attaches to the motherboard using a cable, the cable might be at fault.
2) It might be that the mouse is, in fact, loading things down too heavily or that the voltage levels are insufficient.
3) You could have a defective line receiver/transmitter IC.
 
Seems weird that 2 motherboards are doing the same thing. Is the ribbon cable connected properly on the mobo? I know the OP has check this but wouldn't hurt to recheck.
 
Chuck(G) said:
Let's summarize.

3) The OP is certain that the mouse once worked on this board.
Click to expand...
I'm not sure that this has been absolutely confirmed by the OP.


Chuck(G) said:
My questions:

1) Have you tried testing the board using loop-back connectiors?


My suspicions:

1) if the serial port connector attaches to the motherboard using a cable, the cable might be at fault.
Click to expand...

fatwizard said:
This time I tested the built in serial ports with Checkit and a loopback connector. COM1 and COM2 pass with flying colors.
Click to expand...
The cable is suspect as the cable is not used with the expansion card's ports. Maybe CheckIt doesn't test everything necessary?
 
I had the same problem with two computers, but in that case, it's because I'm using a Microsoft mouse with a PS/2-to-serial adapter.

I haven't been able to find the problem with either one yet.
 
Yeah, all very good suggestions. Indeed I have checked the cable, as I have about 10 such cables and none of them make a difference. I even tried connecting them backwards just in case. I have tried three serial mice now. All Microsoft mice. They all work on this system if I use a separate serial card. I even changed the power supply. I have the same results on three motherboards so far.

I will check voltages on the ports tonight.
 
Unknown_K said:
Serial port enabled in BIOS? What are the settings?
Click to expand...

The Plato board showed COM1 as 3F8H and IRQ 4, COM2 is 2F8H and IRQ 3. The Shuttle board doesn't specify in CMOS, but Checkit reports it is using the same resources. This is the same on all three boards. I toggled them off and back on with no affect. I tried my inport card and mouse and it loads the driver as expected.
 
MikeS said:
If the com port is connected to the MB with a cable, check the cable; the pinout was not always 'standard'.
Click to expand...

I just had that exact problem two days ago, I replaced a board in an IPC pentium system with 486DX-66 board and Win98 would not detect the serial mouse.
I wired up a loopback plug and it was also failing the looppback test so on a whim I swapped the cables and it solved the problem.
 
Unknown_K said:
Inport card, that is for a bus mouse then not a serial mouse.
Click to expand...

Indeed. I was using a bus mouse with the Inport card. I have several bus mice because they will work with my Amigas through an adapter.

I am happy to report that the culprit has been identified. I have several PCI video cards, but I can't find them just now (hoarder's lament) so I used the little Diamond Stealth 2500 PCI video card that I generally use on the bench for testing. If that card is in the system, the mouse is not found on the built in serial ports. It doesn't affect the serial expansion card. The serial ports were working with the Stealth card in place. The ports were found by MSD and Checkit, and would pass diagnostics with a loopback plug. When I swap in one of my ISA video cards, the mouse driver loads and everything works as expected.

I lacked the imagination to suspect the video card, but everyone's feedback kept me looking until I finally stumbled on the culprit.

My thanks to all
 
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