What is an economical software program and hardware interface to program DCC decoders by computer?
Many people, including myself, use JMRI DecoderPro, which is open source software that's free! ;D
They also have something called PanelPro that's supposed to let you run your layout from a computer. I haven't tried it, so can't comment on how well it does or doesn't work.
JMRI's webpage can be found at: http://jmri.sourceforge.net/help/en/html/apps/index.shtml (http://jmri.sourceforge.net/help/en/html/apps/index.shtml)
The hardware you'll need will depend on which DCC system you're using.
Len
stand alone programmers like the Digitrax PR-3 or SPROG
do not have to be connected to a DCC system to program with decoder pro.
Either with power supply run $80-100.