[LightningGSX]

I'm talking about actual voltage/current to power the device, not signal level power.The USB provides 5v up to 500ma to power external devices, while serial provides no voltage or current for external devices.The supposed self powered programmers work by robbing power from signal or handshaking lines, something RS-232 isn't designed for, and can only supply a very small amount power anyway.RS-232 is supposed to have +/- 12v signal levels, which even at that level, can barely power low current programmers.With newer computers and laptops, the drivers only have +/-5v, thats why you couldn't get your programmers to work.I would imagine AEM uses serial as a cost saving measure only, as USB is more expensive and difficult to implement.Other than cost, RS-232 is far inferior to USB.