1). IrDA is something like the Infrared Data Association. I'd look it up but their specification is so poorly written I wouldn't do them the honor. Its the protocol specification for infrared datacommunications between things like laptops, PCs, Palms, portable printers and probably some digital camaras. Note that its note the specifications for TV remotes and such.

Oh yeah, WinCE Battery-Drainers support IrDA too.

IrDA sounds wonderful until you figure out that the standards committee immediately started companies offering expensive working code for everyone that couldn't decipher their convoluted specification. They promised to improve the specification but were too busy getting rich.

2). IrLAP is one of the protocol modules under IrDA. Its a layered protocol and that is part of it.

3). Bluetooth is an omnidirectional radio protocol good for about 75 feet and is being pushed hard by the data phone companies. It uses an open frequency range so you don't have to buy channel rights. Many chip solutions are becoming available making this soon the only viable protocol for proximity wireless data transfers.

Of course it has security issues that are an undiscovered pandora's box. IrDA on the other hand is line of sight to about 3 meters and if faster. Since IrDA doesn't transmit through walls, it has some security advantages.

4). RTOS stands for Real Time Operating System. Its a package for those that won't write their own. :)

aka j