 The VNET networking software became the basis for IBM's internal corporate data network {which had over 3,000 IBM processor nodes} and the university BITNET network which was facilitated by Cambridge in conjunction with Yale Computer Center {Grey Freeman} and CUNY computer center {Ira Fuchs}.MacKinnon served at Cambridge for 18 years and in July 1992 had the unenviable responsibility of closing CSC when IBM decided to close all its scientific centers worldwide.IBM closed the center on July 31, 1992.