Mouse serial adapters are not universal. That doesn’t look like the Microsoft adapter, so more than likely won’t work.

Here's a pic of a the actual Microsoft adapter - Note that you can see "Microsoft" on the bottom
(and yes, they did come in at least two colors - and the green one also says "Microsoft on
the bottom")

Are you sure this is a serial (COM) port compatible mouse?
I can't find one right now, but IIRC the ones that came with the adapters said something like
"Serial and Mouse port compatible" yours make no mention of serial.

And I did at one time have Microsoft mice that were *only* mouse port *or* serial
(different connectors on the mice, and no adapter)

Dave ::: https://dunfield.themindfactory.com ::: "Daves Old Computers"->Personal

Btw - if you can measure connectivity and want to confirm that your is right for Microsoft mouse,
I can measure it and post the pinout (no doubt you could find one online)

Dave ::: https://dunfield.themindfactory.com ::: "Daves Old Computers"->Personal

I tested the mouse with a PS/2 to USB adapter and it works that way. I don’t think it supports serial.
Would be interesting to check the pinout for the blue PS/2 -> serial adapter.

luRaichu wrote on 2025-02-27, 20:16:

I tested the mouse with a PS/2 to USB adapter and it works that way. I don’t think it supports serial.
Would be interesting to check the pinout for the blue PS/2 -> serial adapter.

Your pics show a PS/2 connector on the mouse. All the Microsoft USB and PS/2 compatible mice I
have have USB connectors and a USB->PS/2 adapter to allow it to work in a Ps/2 port.
- And they all say "USB and PS/2 compatible" on the bottom label.

These mice have an internal controller "smart" enough to figure out what kind of
connection it's plugged in to, perform either USB or PS/2 signalling - the adapter
has no electronics, it just moves wires around to a different connector..

There are adapters which take PS/2 (only) mice (and keyboards as well) and convert them to
USB by having a little microcontroller inside that "talks" PS/2 on one side and
USB on the other, translating back and forth between them...

If you are using that type of adapter, all it's telling is that the mouse works via PS/2.

I'll measure the Microsoft adapters I showed earlier and post the pinout shortly.

(BTW, "it doesn't work with this serial adapter" and "I don't think it supports serial" makes
a kinda inconsistent question?) - do I misunderstand something?

Dave ::: https://dunfield.themindfactory.com ::: "Daves Old Computers"->Personal

I do not think that Mouse Port 2.1 is fully Serial compatible, it does not list 12v and 5v like the MS Serial-Mouse Port 2.0 or MS Serial Mouse 2.1...
but could be wrong. And YES the adapter has to be a MS adapter not Logitech or generic

OK .. I've pinned out the MS PS/2 -> Serial adapter

I used standard DB-9 serial pin numbers.

View is from the end(s) of the adapter, female connectors (not pins)

Dave ::: https://dunfield.themindfactory.com ::: "Daves Old Computers"->Personal

DaveDDS wrote on 2025-02-27, 20:29:

There are adapters which take PS/2 (only) mice (and keyboards as well) and convert them to USB by having a little microcontrolle […]
Show full quote

There are adapters which take PS/2 (only) mice (and keyboards as well) and convert them to
USB by having a little microcontroller inside that "talks" PS/2 on one side and
USB on the other, translating back and forth between them...

If you are using that type of adapter, all it's telling is that the mouse works via PS/2.

Yes. I used an active adapter, just to rule out the possibility of the mouse being dead…

DaveDDS wrote on 2025-02-27, 20:29:

(BTW, "it doesn't work with this serial adapter" and "I don't think it supports serial" makes
a kinda inconsistent question?) - do I misunderstand something?

I bought this mouse to use with a serial port. But, I shortly realized it must be PS/2 only. Serial mice have the word “serial” on the back.

Here's the pinout of my adapter.

Well... thats clearly not the same pinout as Microsoft (there were no
standards - most vendors differd).

And it doesn't look like your mouse supports serial, so I don't think
it really matters...

But you should be carefull plugging bus mice into serial adapters.
The PC PS/2 bus mouse port has a +5v power rail.... hence bus mice
are designed to run on a +5v power supply.

A PC serial port does not have any line at +5v, power has to be
drawn parsitically from the DTR, RTS and/or TD lines.
Depending on how they are configured, these lines can be +12v or -12v
and at very low current (they are signals, not power lines).

TD is not a good choice as it toggle +/-12v during data transmission,
I think most drivers set both DTR and RTS high, and the mouse draws
power from both of them.

Serial/PS2 mice will typically detect what it's plugged into (usually
by the presence of +12v and adjust their internal operation differently
to send +12/-12v RS-232 serial data from one of their pins and
the internal program does serial handshaking.

If operatins in PS/2 mode, it transmits 5v PS/2 signals on the
appropriate pins, and program does PS/2 handshaking.

Since it has to work with +/-12v signls (and power) there is
obviously circutry to perform the necessary voltage transation,
which could be implemented in *many* different ways, meaning different
vendors mice could use different pins in the PS/2 port, which
means a different PS/2 adapter.

And mice which were designed to plug into a serial port can handle
the 12v signals (which may be the wrong polarity till the driver loads).

In contrast, mice designed only for PS/2 may not have such safeguards...
fortunately RS-232 serial lines don't generally supply a lot of current
- so *usually* don't damage a bus mouse... but you never know, you are
powering it outside it's save voltage range.

This is why Serial/PS2 mice are almost always labelled as such.

Dave ::: https://dunfield.themindfactory.com ::: "Daves Old Computers"->Personal

Excellent write-up Dave ! A little OT: there are also PS2/USB MS mice that specifically say so on the label.

1)
If your 386 has a 40-pin DIP keyboard controller chip, and you want to use a PS/2-only mouse, your best bet is to adapt your keyboard controller chip to use a PS/2 mouse interposer board, like these: Re: Native PS/2 mouse implementation for 386/486 boards using the keyboard controller soldering required and you would need to use a TSR or modify your BIOS to enable the PS/2 mouse protocol. There are steps on how to do this, but can be unpleasant for some.

2)
Practically, the simplest approach is to buy a serial mouse. Microsoft did make some 3-button mice with a scroll wheel which supported PS/2 and Serial protocols, even though it had a PS/2 connector. The bottom of such a mouse would read Serial or PS/2. Attached is such an example. You can still find these new or used on eBay with the adaptor for about $25.

3)
If not wanting to hunt down mice, you can use a PS/2 to serial protocol converter, as shown here: PS/2 to Microsoft Serialmouse Adapter Converter / Updated First Post / Firmware Update added
Some manufacturers made them in the late 90's and early 2000's, but those are harder to find now. There are some made new here: https://www.serdashop.com/PS2TOSERIAL but keep in mind that if you are behind a KVM, there could be some mouse pointer lag, depending on the mouse and your screen resolution.

I always use option 1.

Horun wrote on 2025-03-02, 03:35:

Excellent write-up Dave ! A little OT: there are also PS2/USB MS mice that specifically say so on the label.

Thanks... and yeah, that's what many of my mice are - but since USB wasn't mentioned as a
desirable option, I didn't bring that up much - I did mention a few posts back that these have
"USB and PS/2 compatible" on their labels...

Dave ::: https://dunfield.themindfactory.com ::: "Daves Old Computers"->Personal

I went ahead and bought a 3-button serial mouse on evilBay for around $10. Brand new in unopened box...
Funny you mention ROM-BIOS modding feipoa. I was always toying around with the idea of hacking existing ROMs to add custom graphics on boot (or startup sounds, for Macintosh computers). Like replacing the logo on AMI BIOSes just for fun. Too bad my 386 board's Phoenix BIOS doesn't draw a logo so that'd be a harder mod.

Hmm, 386 era Phoenix BIOS mods aren't something I can recall this forum discussing. I wouldn't know how to mod this BIOS to add PS/2 support or to alter the logo. AWARD BIOSes have some tools which help you extract the BIOS photo and replace if desired.

DaveDDS wrote on 2025-03-01, 03:38:

Well... thats clearly not the same pinout as Microsoft (there were no standards - most vendors differd). […]
Show full quote

Well... thats clearly not the same pinout as Microsoft (there were no
standards - most vendors differd).

And it doesn't look like your mouse supports serial, so I don't think
it really matters...

But you should be carefull plugging bus mice into serial adapters.
The PC PS/2 bus mouse port has a +5v power rail.... hence bus mice
are designed to run on a +5v power supply.

A PC serial port does not have any line at +5v, power has to be
drawn parsitically from the DTR, RTS and/or TD lines.
Depending on how they are configured, these lines can be +12v or -12v
and at very low current (they are signals, not power lines).

TD is not a good choice as it toggle +/-12v during data transmission,
I think most drivers set both DTR and RTS high, and the mouse draws
power from both of them.

Serial/PS2 mice will typically detect what it's plugged into (usually
by the presence of +12v and adjust their internal operation differently
to send +12/-12v RS-232 serial data from one of their pins and
the internal program does serial handshaking.

If operatins in PS/2 mode, it transmits 5v PS/2 signals on the
appropriate pins, and program does PS/2 handshaking.

Since it has to work with +/-12v signls (and power) there is
obviously circutry to perform the necessary voltage transation,
which could be implemented in *many* different ways, meaning different
vendors mice could use different pins in the PS/2 port, which
means a different PS/2 adapter.

And mice which were designed to plug into a serial port can handle
the 12v signals (which may be the wrong polarity till the driver loads).

In contrast, mice designed only for PS/2 may not have such safeguards...
fortunately RS-232 serial lines don't generally supply a lot of current
- so *usually* don't damage a bus mouse... but you never know, you are
powering it outside it's save voltage range.

This is why Serial/PS2 mice are almost always labelled as such.

Dave ::: https://dunfield.themindfactory.com ::: "Daves Old Computers"->Personal

Can I get some help please, with fabricating this "opposite" type of adapter, for a MS Serial Mouse like this one?

Using this adapter into PS/2, the mouse seems to be communicating only through the following 4 pins of it's DB-9 connector:
(hopefully i'm not messing up the numbering for the connector in the picture)
1 [Data Carrier Detect]
5 [GND]
8 [Clear To Send]
9 [Ring Indicator]

From the PS/2 side, i recon I should connect GND to GND, and probably the +5V to CTS...
PS/2 mouse Clock & mouse Data, should probably go to the other two, but which to where?
And also, do I need to bridge any connections?!

Thanks! 😁

LATER EDIT:
I made it work! 😁
The corect wiring is:
1 [Data Carrier Detect] -to- PS/2 Male "Clock"
5 [GND] ------------to- PS/2 Male "GND"
8 [Clear To Send] ----to- PS/2 Male "+5V"
9 [Ring Indicator] --to- PS/2 Male "Data"

I got brave (or reckless --depending on how you look at it), and tried some combinations:

1 [Data Carrier Detect] - to - PS/2 [Data]
5 [GND] ---------- to -- PS/2 [GND]
8 [Clear To Send] --- to -- PS/2 [+5V]
9 [Ring Indicator] -- to - PS/2 [Clock]
This didn't give any errors, but just didn't work.

1 [Data Carrier Detect] - to - PS/2 [Data]
5 [GND] ---------- to -- PS/2 [GND]
8 [Clear To Send] --- to - PS/2 [Clock]
9 [Ring Indicator] -- to - PS/2 [+5V]
This was per ChatGPT's recommendation, and gave a PS/2 Keyboard misconnection(or something like that) error at POST.
But as my PS/2 keyboard was still working, I skipped the error and booted into XP, where the keyboard stopped working.
So I tried putting a diode on [Data], and another on [Clock] (again, per ChatGPT's recommendation), so the signal could only go from the mouse to the PC.
This fixed the error, but the mouse still didn't work.

All that's left now, is to try and put [+5V] on [Data Carrier Detect], with the two available combinations left between [CTS] & [RI], and [Data] & [Clock].

But in all honesty, i'm kinda scared to blindly try [+5V] to [Data Carrier Detect] ..
Any suggestions???

Ok, not sure what you are trying to do ... the mouse you just showed is different that the mouse you showed in your
initial post - the initial was a 2nd gen MS Mouse with a PS/2 connector, and I understood that you wanted to connect it
to a serial port - some MS mice with PS/2 connector can be adapter to a serial port, and I gave the pinout to make one
matching the MS one (but your's didn't indicate on bottom that it was PS/2 compatible)

The mouse you just showed is a 1st gen MS mouse with a serial connector (you mentioned buying a 3-button
serial mouse on Ebay - but the one shown is 2-button). It should work serial "as it" (I still have a couple of these).

So what are you trying to do? - adapt the last one shown to PS/2?

I don't recall ever seeing one of these which could be adapted to PS/2 - doesn't mean they didn't
exist - but I never encountered one - you didn't show the bottom - does it say it's PS/2 compatible?

DaveDDS wrote on 2025-10-06, 21:13:

Ok, not sure what you are trying to do ... the mouse you just showed is different that the mouse you showed in your initial post […]
Show full quote

Ok, not sure what you are trying to do ... the mouse you just showed is different that the mouse you showed in your
initial post - the initial was a 2nd gen MS Mouse with a PS/2 connector, and I understood that you wanted to connect it
to a serial port - some MS mice with PS/2 connector can be adapter to a serial port, and I gave the pinout to make one
matching the MS one (but your's didn't indicate on bottom that it was PS/2 compatible)

The mouse you just showed is a 1st gen MS mouse with a serial connector (you mentioned buying a 3-button
serial mouse on Ebay - but the one shown is 2-button). It should work serial "as it" (I still have a couple of these).

So what are you trying to do? - adapt the last one shown to PS/2?

I don't recall ever seeing one of these which could be adapted to PS/2 - doesn't mean they didn't
exist - but I never encountered one - you didn't show the bottom - does it say it's PS/2 compatible?

You're confusing me with the OP. Im a different user 😀
I know this is an older MS Mouse than the one being discussed, but maybe this info is useful to someone.

Anyway, I made it work! 🥳
The corect wiring for that cable adapter is:
1 [Data Carrier Detect] -to- PS/2 Male "Clock"
5 [GND] ----------to-- PS/2 Male "GND"
8 [Clear To Send] ---to- PS/2 Male "+5V"
9 [Ring Indicator] --to- PS/2 Male "Data"

Also here are 2 of these same serial mouse type, but with different stickers.
They both have PS/2 adapters, even though only one label specifically mentions dual-mode support.
(which I think is very interesting!)

This first one is a picture of the one that I copied the adapter from.
Unfortunately, mine hasn't got it's sticker anymore, so I can't compare.. but the chip inside(mine) is a Motorola SC88715DW from 1989 [L.E. and the cable has 7 wires + 1 for shielding].

And this second one is another one I also found online for sale.
The label wasn't clear, but the user gave the Part No. of the mouse in the description, so I found a clearer picture of a label with the same P.N. elsewhere.