It is often said that branch change is possible while going for MS/ PhD in USA. But almost all examples (as seen on university sites and various blogs) are of someone completing undergraduate studies (ie BE, BTech) from ‘Circuit’ branches of engineering i.e. Electrical, Electronics, Telecom, Instrumentation etc and joining MS/PhD in CS.

* How difficult it is to go for MS or PhD in CS, having studied in ‘Non Circuit’ branches like Mechanical, Civil, Chemical and Aeronautics Engineering?
* Are there people out there?
* What one should do if one has a strong drive, skills and suitable projects, seminars, publications to support the same?

(My query refers mainly to top ranking colleges, say top 20)