The PhD qualifying exam is typically taken in the second semester of the first year or the first semester of the second year. It consists of four parts, all of which must be passed at the same time in order to pass the overall exam. There are three 90-minute written exams in these areas: data structures and algorithms, programming languages, and operating systems. These exams are based on a reading list, and do not necessarily correspond directly to any course. The fourth part of the qualifying exam is a small research project to be done in cooperation with your advisor during the same semester as you take the written exams.
A student with a Master's degree in computer science or computer engineering may be granted up to 30 credits when he/she enters the doctoral program. The remaining 60-90 credits are accumulated through course work at Stevens. For most students, most such ``course work'' comes via research-for-credit course numbers; that is, the research you do with your advisor comprises most of the required 90 credits.
It should be clear that the Stevens Computer Science PhD program is research-oriented. Students are expected to study full time and to be on campus working closely with their advisors on research during the academic year. Typically, newer students spend their summers doing internships at industrial labs. (There are several in the region, such as IBM T.J. Watson, Lucent Bell Labs, AT&T Research, and others). Senior students completing their theses often spend summers on campus.