Seeking High IMP Reliability in Maintenance of the 1970s ARPAnet

Abstract

During the first years of ARPAnet operations, computers were not highly reliable, but the network was built from standard computers and was expected to function as a utility with high reliability. We managed to achieve the desired reliability, as perceived by ARPAnet users, by making innovations in hardware, maintenance procedures, software, and network operations. This article draws heavily on the personal experiences of the authors, many of which have not been previously reported in the literature. Our focus is on the 1969–1975 time period when ARPAnet was the sole responsibility of the Advanced Research Projects Agency (ARPA). A 2018 paper (Fidler et al., 2018) discusses ARPAnet maintenance after 1975. The preparation of this article was spearheaded by David Walden. David recruited the other 2 authors, prepared the outline of the paper he envisioned, and drafted some sections. Sadly David's deteriorating health prevented him from contributing his usual amount of energy and knowledge, but this article would not have been written without him.