Here is an image, is this your pill?
wallsrx.com/services/cpident.cfm?CPNum=854&folder=017&photo=acet009g
If so, PooJ is correct.
However if it is different than that image, it may be
Cipro which is a plain white round pill with the number 512, without the score line.
verwon@gmail.com
My information is not guaranteed correct. I do not get them right all the time, but I do enjoy the hunt~