On Tue, 26 Apr 2011 11:24:08 -0700, pyotr filipivich
wrote:

I've a wall wart which is rated 12 V DC at 1 amp output

The router is (I think) expecting 12 VCD at .5 amp.

And I correct in assuming that the wall wart will not "over supply"
the device - that its rating is essentially the max amperage it will
output, while the router is the amount it will draw to function?

That seems to make sense, to me. At this hour of the morning.

Yes, more than likely. Make sure that the supply is regulated (just
stick a voltmeter across it without a load and read the voltage if
you're not sure- it should read 12V within a fraction of a volt).
If it weighs only a few ounces, it's a switching supply and they're
virtually always regulated.