Post by John B. SmithI have been using a Microsoft wired USB mouse for several years. I
noticed these USB-PS2 adaptors on Amazon and ordered them.
https://www.amazon.com/dp/B09WV5JMKS?psc=1&ref=ppx_yo2ov_dt_b_product_details
My idea was I could save a USB jack on my PC if I switched to PS2.
So I plugged the adaptor into the mouse cable and plugged the cable
into the green PS2 port. Booted Win7 and cannot move mouse cursor. It
occurred to me that Windows installed the mouse as a USB connect and
now cannot recognize it when I connect it with PS2. But I'm only
guessing. IF I'm right, what's the easy way to re-install the mouse
without leaving myself mouseless in the middle of doing it?
If a mouse is dual-mode, it comes with a green adapter in the box.
The adapter is a passive adapter, just wires inside. The manufacturer
does not usually "hide" the fact it is dual mode and can use a passive adapter.
This is why, you don't buy the passive thing, unless the box had an
identical passive and you lost the original green one. My Logitech mouse
is dual mode and came with a passive adapter in the box. The green adapter
is sitting right in front of me, on the "trinket row".
The mouse figures out whether the wires currently speak USB
protocol or whether the wires speak PS/2 clock-with-data.
Instead of D+ and D-, it might check to see if one is DATA, the other CLK.
VCC USB 5V system, strap resistors to D+, D- for signaling
D+
D-
GND
Pin 1 +DATA Keyboard Data [I could have done a better
Pin 2 Mouse Data on split-color connector job on this table, and I really
Pin 3 GND Ground should have made three tables,
Pin 4 Vcc +5 V DC at 275 mA one table for Mouse, one for Keyboard,
Pin 5 +CLK Keyboard Clock and then this Combo pinout for split-connector]
Pin 6 Mouse Clock on split-color connector 4 wires, 4 wires, 6 wires
*******
There are also USB (host end) to PS/2 (peripheral end) active adapters.
This would allow, say, a PS/2 protocol only keyboard to be used with a USB port.
The very first one of these had a firmware bug and stopped working
after precisely ten minutes. The chip had first layer programming
(permanent ROM) and could not be flashed. The manufacturer wanted
the cheapest chip possible, and the utter cheapness (cannot flash up) cost the
manufacturer around $250K in losses.
Later ones worked.
A variant, was someone made a PCI to USB2 addin card, and put a USB to PS/2 active
adapter on the card, so you could plug in a PS/2 device.
*******
Windows scans for USB mice, PS/2 mice, RS232 Serial mice.
For RS232 Serial mice there may be a "fast detect" setting
of some sort, which tells Windows to not look for a serial mouse.
When Windows 10 came out, I used to connect all three mouse
types, for fun. Early Windows 10 would detect two out of three
items. I think it used to do a decent job on RS232 serial mice.
Maybe the USB mouse would disappear sometimes. Later versions
of Win10, I no longer test for this (boring), but I think it
was eventually getting all three.
Windows 10 tried to speed up boot, by looking for items
this time, which were present the last time. This might have
been why, initially, the USB item went missing. Maybe the PS/2
was enumerated first, assume to be the "anointed one", and
this tended to rubbish attempts to get the other one to show up.
The philosophy at Microsoft may have changed at some point,
so that better detection on each cycle would (eventually) happen.
For storage, there are still cases where a driver is actually
missing and you screwed it up. If you cloned a SATA (OS) drive,
to an NVMe (using Macrium Rescue CD), then unplugged the SATA and
ran with the NVMe, it would print "inaccessible boot device"
and the boot would fail. You would need to boot the SATA,
while the NVMe was present, Windows would install the NVMe
driver on the SATA OS... then you'd clone over to the NVMe
and when it ran by itself, it finally had a driver to talk
to itself. While Windows has "a lotta drivers in the box",
there are still scenarios where the thing you think is
in place, isn't actually where it needs to be.
Paul