rebinding keys to functions

[perryh at pluto.rain.com]

Roland Smith <rsmith at xs4all.nl> wrote:
> Writing a driver to detect if headphones are connected sounds
> much more complicated to me than connecting a couple of switches!
> I mean, you'd have to measure something like the impedance of
> the jack. Surely that is more expensive than a simple switch?

Or use a simpler jack, with one switch that connects to ground or
not depending on whether the plug is inserted or not.  It probably
costs a cent or two less than the usual two-switch variety, and this
is a BOM (Bill Of Materials, i.e. per-unit-built) savings.  Writing
the driver is an NRE (non-recurring engineering) expense which can
be amortized over -- the manufacturer hopes -- a huge number of
delivered units.