geekretro wrote on 2025-02-08, 01:53:

Update: I have read a post about AT power connector corroded, I check mine and I clean them. After that, mouse was working! but […]
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Update: I have read a post about AT power connector corroded,
I check mine and I clean them. After that, mouse was working!
but the onboard COM still not working but with ISA card the
mouse is functionnal.

So COM are perhaps dead or still to know the correct pinout.

So - is it a serial mouse? If so, whats the ISA card?
Or is it a completely separate ISA mouse card which would have nothing
to do with serial?

Just trying to figure out exactly whats working/not working. It the
mouse is serial... it suggests the COM port at least "partially" works,
or perhaps the ISA card you mention is a separate serial card?

A good way to check out COM ports is with my SDT (Serial Debug Terminal)
It's in a couple places on my site, but I do know it is the the DDLINK.ZIP download.
DDLINK also talks to COM ports (you can see if it runs with the COM port
of fails "Cannot open COM") - also DDLINK.TXT has some information
about COM connections/pinouts (as does SDT F9-help);

Basically SDT will let you raise/lower the output signals and monitor the
input signals in real-time. With the pinout information you know which
pins to monitor for the changes, and if the outputs work, which to loop
back to make the inputs echo those outputs.

If the pinout is wrong, you should still see signals change on the
DB-9 (just the wrong ones), or go directly to the mainboard pins to
figure out it's pinout and the correct wiring for a cable to the DB-9.

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

Yes it's a Microsoft Serial 2.1a

The ISA card is separate and is a 1987 DTK PTI-209 ISA 8BT SERIAL PARALLEL PORT 286 Courier I/O Card

I'm no expert in using some terminal, I have used a multimeter the other day but I would need a course 😉

But now, the mouse is working. I will check it out with the ebay seller I have bought the 4dps, I will ask him if he do know the correct pinout for the onboard com

geekretro wrote on 2025-02-08, 04:48:

Yes it's a Microsoft Serial 2.1a ... The ISA card is separate...
I'm no expert in using some terminal, I have used a multimeter the other day but I would need a course 😉

So what COM port is the ISA card?
Normally the "built in" COM ports of the mainboard are COM1 (and COM2
if present) - is the ISA card COM3? If not, it could be conflicting
with the ones on the mainboard.

You can use SDT to see what COM ports you have:
SDT P=1 .. P=2 .. P=3 .. P=4
Will either start, or fail: Unable to open COM port

A terminal is quite simple, it shows any data received on the serial
port and tramsmits anything you "type". Normal terminals usually have
some sort of signalling requirements (like driving DTR and RTS, and
requiring DSR and CTS to be ON) - but SDT lets you raise/lower the
outputs via functions keys, and shows you the real-time status of the
inputs.

SDT has a 80x24 main TTY screen and the 25th "status" line at the bottom
shows you which F keys to press to toggle the output signals on the left,
and state of the input signals an the right - in all cases, a signal name
shown in lower-case means it's OFF, while upper-case means it's ON.

With a multimeter set to a DC scale suitable for +/-12v you can look
at the RS-232 signals directly on the external COM connectors.
You generally don't want to short pins with the meter probe, or have
to hold it in place while you change them via software - so I like to
use little jumper caps that fit over the pins to make connections
(you can get-by without, just be careful not to short them, and put
the probe down when making changes - then re-measure)

For the purposes of measuring them, you can use most-any system ground
as the reference point - if you have 5.25" and/or IDE type drive
power cables, the two center pins (black) are gouund and usually make
an easy place to put a meter probe.

If the RS-232 connector appears wrong, you can look directly at the
header pins on the mainboard.

Keep in mind that input pins may be mildly driven .. a 1K resistor
is enough to pull inputs down, but not really affect outputs.

(A very handy test tool you can make is two leds back-to-back
reversed with a 1k resistor in series ... this will light one of
the leds on an active line, and which LED will tell you polarity)

I'll follow this message with another one explaining what COM port
signals are how it all works!

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

Some "education" on serial (COM) ports:

Serial ports use RS-232 which is one of the oldest communications
standards. Back in the day, most communcations was via MODEMs some of
which used a LOT of signals, so RS-232 provides for them, hence the
original RS-232 serial connector is a DB-25 - with 25 pins. Many of
these weren't used then, and most are not used now... The signals
commonly used are:
RXD - Receive Data (C)
TXD - Transmit Data (T)
DTR - Data Terminal Ready (T)
DSR - Data Set Ready (C)
RTS - Request To Send (T)
CTS - Clear To Send (C)
CD - Carrier Detect (C)
Ri - Ring Indicator (C)
The "endpoints" are called "DTE" (Data Terminal Equipment - ie: PC) and
"DCD" (Data Communication Equipment - ie: Modem)
- in above: (T) means driven by DTE, (C) means driven by DCE

Most "modern" PCs use a DB-9 connector, allowing for all 8 of the above
+GND (ground)! Traditionally "devices" used female connectors (holes)
and cables used male (pins) - but somewhere along the way, the PC was
designed to "look like a cable" with pins on it's rear RS-232 connctors.

1+-----------+
2| 1 2 3 4 5 |  1=CD 2=RXD 3=TXD 4=DTR 5=GND
3 \ 6 7 8 9 /      6=DSR 7=RTS 8=CTS 9=RI
4  +-------+

Within the PC the signals are as you would expect: On=+5V, Off=0v
but RS-232 is inverted +/-12v (actually the spec. says 3-25v, but the
PC has +/-12v supplies so that's what it uses: On=-12v, Off=+12v

(hopefully I remembered all this right - it has been YEARS!)

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

This is the COM1 from the separate ISA card right now, this is working as alternative solution from using the one onboard.

Thanks for the info! I will keep them as useful info

Meanwhile, my ebay seller of the 4dps told me he will send me a cable to use with onboard COM...

geekretro wrote on 2025-02-08, 12:41:

This is the COM1 from the separate ISA card right now, this is working as alternative solution from using the one onboard.

Thanks for the info! I will keep them as useful info

Meanwhile, my ebay seller of the 4dps told me he will send me a cable to use with onboard COM...

Did that cable work?

Yes the cable works but unfortunately I still don't know the correct pinout...