At the Russian-language forum, we discussed for a long time the possibility of using one IRQ with different COM ports, and as a result, everyone agreed that this is possible, only if all ports are on the same ISA card. And the card itself performs IRQ arbitration. The ISA bus does not allow different ISA cards to use the same IRQ at the same time. You can read the discussion here: https://www.phantom.sannata.org/viewtopic.php … =33459&start=27

derSammler, if you doubt that the mouse drivers have problems with the COM3/COM4, give me a list of drivers that work fine. And I will give you a list of drivers that can not find a mouse on COM3/COM4 at all, or without a hint. I tested several drivers, and only the IBM driver worked correctly.

As for the KVM, I do not have such a device.
Yesterday I sent one adapter to feipoa, I'm sure he will test the device with KVM.

I would really like to know what this KVM problem is supposed to be. How is it different than a PS/2 mouse plugged in directly? If it's just an overflow of fast PS/2 messages on a slow serial bus, then 1) what does the KVM have to do with it, and 2) wouldn't the 1:2 -- 1:4 rate dividers solve that?

SirNickity wrote:

I would really like to know what this KVM problem is supposed to be. How is it different than a PS/2 mouse plugged in directly? If it's just an overflow of fast PS/2 messages on a slow serial bus, then 1) what does the KVM have to do with it, and 2) wouldn't the 1:2 -- 1:4 rate dividers solve that?

I did not quite understand your question.
Using the adapter differs only in the software part. There can be no overflow. When a mouse is connected to the PS/2 directly, the PS/2 driver works with it. When a mouse is connected through the adapter, the driver for COM mouse is used. Data received from the PS/2 mouse is transmitted almost unchanged.

Rio444, do you know which mouse drivers will and will not work with the emulator card? Does middle button work? What about scroll wheel?

Yes, KVM testing is my priority!

feipoa wrote:

Rio444, do you know which mouse drivers will and will not work with the emulator card? Does middle button work? What about scroll wheel?

Under DOS, I could not find a driver for serial mouse that would not work. In Windows, the drivers are "Microsoft Serial Mouse" or "Logitech Serial Mouse" and "Microsoft Wheel Mouse". For some reason, the "Logitech Serial Mouse" driver did not work in Win 3.11. Perhaps it is for some special Logitech mouse. The middle button and the wheel work if supported by the driver. Under DOS, the middle button is supported by most drivers. Wheel is supported by CuteMouse driver. Win98 and WinNT 4.0 automatically enable wheel support. For Win95, you need to install the special driver "Microsoft Wheel Mouse Driver". Later, I will post a version that works. For other versions of Windows, I did not look for drivers with wheel support.

Here is the driver with mouse wheel support for Windows 95. It is installed as a ordinary program by running setup.exe.
https://yadi.sk/d/6pmfdu0GRNZzpQ

I recall with your keyboard controller PS/2 TSR that I was unable to use the Logitech mouse driver in Win 3.11 and DOS.

OK. I will test scroll wheel as well in Windows 95. Is that the same driver as for the Microsoft serial mouse with scroll wheel? I have one of those Microsoft mice that can do serial or PS/2, so I'd test tracking quality with it first in serial mode, then switch over to the Emulator with a) same mouse in ps/2 mode, and b) a purely PS/2 laser mouse with scroll wheel. Then test some ps/2 trackball mice.

Did you test scroll wheel in NT 3.51? Which driver did you use for NT 3.51?

I personally think COM 1 or COM 2 is fine. A serial mouse is often installed on COM 1 anyway. Do you guys have more than 2 serial devices plugged into your retro systems?

feipoa wrote:

Did you test scroll wheel in NT 3.51? Which driver did you use for NT 3.51?

The same mouse driver should work in NT 3.51. Have a look here https://driverzone.com/drivers/microsoft/msip20a.htm
Driver msip20a.zip
But I did not check.

I added support for COM3/4. Feipoa, I'm sorry, I hope you are not very upset that your adapter is without it.
After that, I checked the drivers for the ability to work with COM3.

IBM/Microsoft driver ver.8.20 - success!


A4 driver rev.5.01 - fail!


DFI driver rev.1.31 - fail!


Some kind "Pan & LEES" driver - fail!


Vesa driver rev.1.02 - fail.

Earlier I tested CuteMouse drivers and they failed. But now they work successfully! Maybe I made some mistake.
CuteMouse driver rev. 1.9, 2.0, 2.1 - success!

Win 3.11 (integrated driver) - fail!

Win95 - work. But earlier installed driver for wheel mouse - fail!

To enable COM3/4, you must connect the reserved pin 6 to GND. To do this, install a jumper 5-6 or 4-6 or connect pin 6 to any pin labeled "GND".

But I still highly recommend not using ports COM3 and COM4.

Hi, when can I buy one and how much does it cost?

I don't really mind about not being able to use COM 3/4. Is the benefit of using COM 3 or 4 such that you don't need to disable COM 1 or COM 2 ports in the BIOS? So if I set the emulator to use COM 1, I must disable COM 1 in the BIOS? But if I set the emulator card to use COM 3, then I can leave COM 1 enabled? Or have I misunderstood something?

feipoa wrote:

I don't really mind about not being able to use COM 3/4. Is the benefit of using COM 3 or 4 such that you don't need to disable COM 1 or COM 2 ports in the BIOS? So if I set the emulator to use COM 1, I must disable COM 1 in the BIOS? But if I set the emulator card to use COM 3, then I can leave COM 1 enabled? Or have I misunderstood something?

Yes that's right. To use the adapter with COM1, you need to free port 3F8h. To do this, you must either completely disable the COM1 port, or change its address from 3F8h to 3E8h and then it will become COM3. You need to do this with jumpers on your multi i/o card, or in the BIOS, if the COM ports are onboard.

The mouse was one of the very first devices to plug into COM ports (together with modem). Therefore, de facto a mouse on com1 or com2 had become the standard. Manufacturers of other devices knew this and, as a rule, provided for the use of their devices on ports other than COM 1 and 2.

mothergoose729 wrote:

Hi, when can I buy one and how much does it cost?

Four devices were made. But they are already sold. For more devices, the necessary details had not yet arrived. Now almost all components are available. I plan to assemble a few more devices in the coming week. If paying directly to my credit card, price is 25 US dollars or 22.5 Euro + shipping (7 dollars for 1pcs, 9 for 2-3pcs). If paying through PayPal, it’s 2 dollars more, because PayPal charges a transfer fee.

Rio444 wrote:

feipoa wrote:

I don't really mind about not being able to use COM 3/4. Is the benefit of using COM 3 or 4 such that you don't need to disable COM 1 or COM 2 ports in the BIOS? So if I set the emulator to use COM 1, I must disable COM 1 in the BIOS? But if I set the emulator card to use COM 3, then I can leave COM 1 enabled? Or have I misunderstood something?

Yes that's right. To use the adapter with COM1, you need to free port 3F8h. To do this, you must either completely disable the COM1 port, or change its address from 3F8h to 3E8h and then it will become COM3. You need to do this with jumpers on your multi i/o card, or in the BIOS, if the COM ports are onboard.

Oh - so I don't have to disable that particular serial port (COM 1) on my motherboard if I am using the emulator card on COM 1? I turn COM1 into COM3 in the BIOS by adjusting the port to 3E8. So the motherboard will still have two active COM ports: 2 and 3? This raises my next question.

Say I have a serial mouse attached to the [now reassigned] COM 3 and have the emulator setup for COM 1 with a mouse attached. I run the DOS mouse driver, and presumably there are flags to select the COM port desired. Can I leave both mice connected and switch between the mice upon loading the DOS driver by specifying different COM ports? Everything should work as expected, even if the mouse not in use gets moved? And is there any way to have both mice working at the same time, similar to how you can use your laptop's touch pad and a physical mouse simultaneously? Why would I want to do this here? To more directly compare the tracking quality between the emulator and a real serial mouse, without having to shut down the system and reload the driver.

feipoa wrote:

I turn COM1 into COM3 in the BIOS by adjusting the port to 3E8. So the motherboard will still have two active COM ports: 2 and 3?

Yes, it will. But you cannot use COM1 and COM3 at the same time, because they share the same IRQ, similaraly COM2 and COM4.

feipoa wrote:

Say I have a serial mouse attached to the [now reassigned] COM 3 and have the emulator setup for COM 1 with a mouse attached. I run the DOS mouse driver, and presumably there are flags to select the COM port desired. Can I leave both mice connected and switch between the mice upon loading the DOS driver by specifying different COM ports? Everything should work as expected, even if the mouse not in use gets moved? And is there any way to have both mice working at the same time, similar to how you can use your laptop's touch pad and a physical mouse simultaneously?

You definitely cannot use mice on COM1 and COM3 at the same time (due to the same IRQ). But you can try to do this on COM1 and COM2. If COM2 does not have a suitable connector, you can turn COM1 into COM2, and COM2 into COM3. Usually BIOS of the motherboard allows this.
The CuteMouse driver allows you to explicitly specify mouse port number and IRQ. But this driver definitely does not allow to run itself twice. You can test the mouse on COM1, unload the driver and reload it by pointing it to COM2.

Rio444 wrote:

Four devices were made. But they are already sold. For more devices, the necessary details had not yet arrived. Now almost all components are available. I plan to assemble a few more devices in the coming week. If paying directly to my credit card, price is 25 US dollars or 22.5 Euro + shipping (usually about 6 dollars). If paying through PayPal, it’s 2 dollars more, because PayPal charges a transfer fee.

Sweet! I am a customer at that price. I have a turbo XT system on a KVM switch that would be so much more convenient to work with if I could use PS/2 mouse. For my particular board, I think COM2 would work best for me.

certainly interested in this, is there a order process or waiting list?

Rio444 wrote:

SirNickity wrote:

I would really like to know what this KVM problem is supposed to be. How is it different than a PS/2 mouse plugged in directly? If it's just an overflow of fast PS/2 messages on a slow serial bus, then 1) what does the KVM have to do with it, and 2) wouldn't the 1:2 -- 1:4 rate dividers solve that?

I did not quite understand your question.
Using the adapter differs only in the software part. There can be no overflow. When a mouse is connected to the PS/2 directly, the PS/2 driver works with it. When a mouse is connected through the adapter, the driver for COM mouse is used. Data received from the PS/2 mouse is transmitted almost unchanged.

My question is just why people are so concerned with KVMs? I've heard of this a few times around here, but I've never heard what the problem actually IS. Just that using a PS/2 mouse through a KVM and then into a serial converter sometimes makes the mouse cursor laggy. I'm curious if anyone knows what causes that issue.

Overflow could be possible because PS/2 devices are actually relatively fast (or can be, anyway) while the default COM port speed for mouse drivers is usually pretty low. So, a PS/2 mouse sending fast updates could potentially overwhelm a serial converter's buffer, if the converter does not set the device polling rate low enough.

I don't know how often this would happen IRL -- maybe it's the source of the lag people talk about? E.g., a high-DPI device could be sending a slew of update packets, which if sent 1:1 by the serial converter at a lower speed would result in the host processing those updates at a slower interval than the mouse intended when transmitting them, at least until the serial buffer caught up. This could feel like lag. But I don't know why that would be different with or without a KVM, unless the KVM defaults to a different scan resolution than the bare device would. I've got some PS/2 uC code written that I haven't tested yet (pending the time to finish a dev PCB), so I haven't characterized typical PS/2 packet throughput. It's all theory right now, which could be way off.

Aragorn wrote:

certainly interested in this, is there a order process or waiting list?

Yes, I remember if someone showed interest. When the next batch will be ready, I will inform you in order of priority.

SirNickity, I suppose KVM introduces an additional delay when transferring data to the COM port. Separately, this delay is almost not noticeable, but when combined with the delay of the COM to PS/2 converter, it becomes significant.
If the cause is overflow, the delay would be substantial without KVM. I know two conversion algorithms in COM to PS/2 converters. One algorithm simply discards old data from the PS/2 mouse, transferring last or sum of two last mouse movings. Another algorithm continuously summarizes movings received from the PS/2 mouse and transfers the accumulated amount. So can be no overflow.

The adapter has arrived. Once I wrap up the mess I've made with this thread, HELP! - Dead Intel VS440FX motherboard with BIOS EEPROM overheating - SOLVED , I'll test the adapter with my KVM.

Between sets at the gym I decided to test this ISA card out. Would you be willing to send me a photo (top and bottom) of which mice you've tested this adapter with in Windows 95 OSR2.x using msip20a.zip? My luck hasn't been so good in Win95c. And which motherboards did you test? I'm now going to try an actual Microsoft IntelliPoint Mouse with scroll wheel in PS/2 mode (also supports serial) using this driver. I'm using a Batman's Revenge socket 4 motherboard with POD133. DOS was OK. EDIT: Microsoft Intellipoint mouse works on the MB's PS/2 port, but not on the emulator card. I guess I can try some Logitech drivers...

EDIT2: Forgot to mention what I've tried: Logitech MouseMan M-S38 (track ball with middle button), Logitech M-SBF96 (optical with scroll wheel), Microsoft IntelliPoint Mouse Mouse with school wheel

I installed the msip20a.zip file. I tried these drivers in Win95c: Microsoft MousePort Mouse with Wheel (this is the driver which gets selected after installing msip20a and rebooting), Microsoft Serial Mouse with Wheel, and Microsoft Serial Mouse. None of these drivers work with these 3 mice. I even tried them without the KVM.

EDIT3: the default Logitech Serial Mouse works with my 3-button trackball mouse in NT4. Also tried laser PS/2 mouse. No noticable lag in NT4 thru KVM.

EDIT4: for Win95c, the mouse works in Safe Mode. Investigating... I think Win95c is having issues with there being a PS/2 mouse port and trying to use the serial emulator card. I might need to test this in a system which doesn't have a ps/2 mouse port. The BIOS on this board doesn't have a disable feature for the PS/2 mouse port. EDIT5: If I set the PS/2 mouse port to "disable in this profile" and set the mouse to Logitech Serial Mouse, the system won't boot-up. Did you test for the condition in which your motherboard has a PS/2 mouse port, but you are using the emulator card instead and in Win95?

I think I have isolated the problem with Windows 95c and the serial port emulator card. Even though you disable COM 1 in the BIOS, Windows 95c still insists on re-enabling it. By the way, I'm testing on a Nx586 PF110 without a ps/2 mouse port. I was using a bus mouse card before installing RIO444's emulator card.

Perhaps in SafeMode, COM1 isn't actively enabled, which allowed for mouse support in Safe Mode.

Reboot into normal mode, and observe the Standard Serial Mouse settings, and this is what you would see:

I needed to enter Device Manager and disable COM 1 in that profile. I rebooted and the mouse worked, but I get a yellow exclamation on Microsoft Serial Mouse with Wheel, which I I selected after installing the Intellipoint 2.0 software.

I was using a Logitech optical mouse with scroll wheel for testing and the Logitech Serial Mouse drive didn't have a yellow exclamation. I suspect that using COM1 on a system which has a COM1 on board can cause problems with the emualtor card. In the series of images you can see the mouse trying to use IRQ 9, which is impossible because the IRQ's and addresses are hardware set. Given these difficulties, pehaps being able to set the mouse for COM3 or 4 would be of some benefit?

I'm also using the operating system-supplied Logitech Serial Mouse driver for Windows NT 3.51 and it works just fine. Even with using the KVM, I didn't experience any noticeable lag. But i'm unable to get the Logitech optical mouse with scroll wheel working. Perhaps you can retrace your steps and post back?

Is there anything I can change on emulator card to work with COM 3/4?