Parker was a senior research engineer and systems manager for
General Dynamics for eight years and
Control Data Corporation for eight years. He then spent several decades at
SRI International working in information and computer security, retiring in 1997. In 1998, Parker proposed the
Parkerian Hexad, six atomic and orthogonal elements of information security that extend the traditional model of Confidentiality, Integrity, and Availability (the
CIA triad). He later became a retired emeritus senior consultant engaged in writing and lecturing, and his collected papers are archived at the
Charles Babbage Institute at the University of Minnesota. Parker died at the age of 91 on September 22, 2021. ==Lectures==