[Nottingham] New keyboard not working

Paul Sladen notlug at paul.sladen.org
Fri Jun 26 12:07:45 UTC 2015

Hash: SHA1

On Fri, 26 Jun 2015, Bob Marshall wrote:

The protocols spoken along the cable are very different for USB HID
and PS/2.  To save hardware costs, many keyboard manufacturers use a
microprocessor in the keyboard programmed to try *both* protocols and
speak whichever one it detects.  These keyboards can then be shipped
with very cheap 'passive' electrical-only adaptors to change what
looks like a USB port (but speaking PS/2) into a PS/2 port connector.

The microprocessor in the new PowerCool keyboard probably only speaks
USB HID, so a passive electrical-only adaptor will not work.  An
'active' _converter_ would be needed, that speaks USB HID from the
keyboard on one side and speaks PS/2 on the other side.

(A similiar example is that some tablets and smart phones can output
composite video via the headphone jack socket; on these devices a
passive electrical-only cable can be used to connect them to a
television or screen.  But on other devices without that functionality
an HDMI->composite *active* converter cable would be needed, costing
considerably more to produce---like an active USB HID->PS/2 converter).

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