[mythtv-users] How about a "Now Recording" red light?

[Jim Paris]

> I've not personally done it from myth or Linux for that matter, but I
> suspect that with a little work that the parallel port would work well.

	 ioperm(0x378,1,1);
	 outb(inb(0x378)^1,0x378);

will toggle pin D0 on the parallel port at 0x378.  ioperm() requires uid=0.

> It outputs TLL voltage levels with sufficient current to drive an LED
> (with a small series resistor so that you aren't just shorting 5V to
> ground when it's on).  Under Windows this isn't difficult.  

Some modern parallel ports use 3.3V signalling.  Also, they can
typically only source about 2mA, but sink around 24mA, so the 
best would be to flip the LED and connect one side to +5
(from an internal connector or ps2/usb/firewire port).

-jim