September 26, 2005
| 2002 -present | Associate Professor | Department of Computer Science, Audio Technology, and Physics | American University | Washington, DC |
| 1995-2002 | Associate Professor | Department of Computer Science and Information Systems | American University | Washington, DC |
| 1990-1995 | Assistant Professor | Department of Computer Science and Information Systems | American University | Washington, DC |
| 1990 | Staff Scientist | International Software Systems | Austin, TX | |
| 1988-1990 | Research Assignee | Artificial Intelligence Program | MCC | Austin, TX |
| 1986-1988 | Technical Liaison | Artificial Intelligence Program | MCC | Austin, TX |
| 1981-1985 | Adjunct Assistant Professor | Department of Computer Science | University of Minnesota | Minneapolis, MN |
| 1977-1986 | Senior Consultant | Control Data Corporation | Arden Hills, MN | |
| 1977-1986 | Senior Consultant | Arden Hills Programming Division | Control Data Corporation | Arden Hills, MN |
| 1973-1977 | Consultant | Professional Services Division | Control Data Corporation | Portland, OR |
| 1969-1973 | Assistant Professor | Physics | Oregon Graduate Center | Portland, OR |
| 1964-1969 | Research Assistant | Ordnances Research Laboratory | Pennsylvania State University | University Park, PA |
| 1962-1964 | Research Assistant | Ionosphere Research Laboratory | Pennsylvania State University | University Park, PA |
| 1961-1962 | Teaching Assistant | Department of Physics | Pennsylvania State University | University Park, PA |
| 1960-1961 | Member of Technical Staff | RCA Laboratories | Princeton, NJ |