> I see USB->PS2 adapters for sale that claim to work for either USB
> keyboards or USB mice. Should any adapter for one device also work for
> the other, or is there something special about these?
As far as I know, the "magic" is inside the keyboard or mouse itself.
The adapter is small, and passive, and there is no chip inside.
I have a mouse, which claims to be "USB/PS2" and comes with it's own
green colored passive adapter plug. The mouse itself, recognizes
the signals are coming from USB or PS/2 and adapts itself accordingly.
The fact the green passive adapter is bundled with the mouse, is
proof the mouse is a dual-protocol type design.
If your mouse doesn't come with an adapter, there is no reason to
assume it is dual-protocol. If you lost the passive adapter, then
by all means, buy another passive adapter and you can safely use it.
If you have any documentation to that effect, that the product
supports both protocols, then it would be safe to use a passive adapter.
If you have a mouse which is "USB only" internally, then slapping
a passive PS2 adapter on it would be a mistake. The mouse probably
doesn't have printed on it anywhere, that it is dual-protocol. http://ca.startech.com/Cables/Serial...r-MF~GC46MFKEY
"Please Note: This product is designed as a replacement adapter
for keyboards that originally shipped with a PS/2-USB converter"
This one is along the same lines, but doesn't come with the same
warning. It should state the same warning as the other product. http://ca.startech.com/Cables/Serial...r-FM~GC46FMKEY
This one, on the other hand, is an "active" adapter, that converts
from one protocol to another. (The "blob" in the middle of the cable,
tells me it is active.) There are no assumptions about the keyboard or mouse
in this case. But, this product is only available "in one direction".
USB host to PS2 keyboard and PS2 mouse. There is no
PS2 host to USB keyboard and/or USB mouse active adapter that
I've seen. They could make one, if they put their minds to it,
but what market would there be for it ? PS2 is disappearing from
computers as we speak. The market for that kind of active
adapter would also be disappearing. I'm really surprised that
Chesen went to the trouble of making a chip for this. http://www.startech.com/Cables/USB-2...apter~USBPS2PC http://www.chesen.com.tw/download/pc...C0101A_160.rar
You can also see the Chesen chip, on this PCI adapter board. It's
the 16 pin chip on the lower left. It converts from the USB chip
on the right, to the PS/2 keyboard and PS/2 mouse connectors on
the card faceplate. The Chesen chip is an actual processor inside,
with its own RAM and firmware. http://images10.newegg.com/NeweggIma...124-045-03.jpg
If Chesen wanted to, they could make it work in the reverse direction
(probably a complete redesign, reusing some of the IP inside).
I'm wondering if they've made their money back on making that one
or not. The engineering to make that would not be cheap, and they
wouldn't be charging more than $5.00 for the chip. Probably a lot less.
The adapters are available at quite reasonable prices, so the profit
margins must be small.
Can a USB keyboard or mouse be damaged by usage of the passive adapter ?
I don't know the answer to that question.
Maybe someone else has tried it, and survived ? I'd have to scan the
500 page USB spec for the rest of the day, to answer that question.