The COM computorized conferencing system has been in regular use on the DEC system- 10 computer at the Stockholm University Computing Center since March 1979. This report summarizes the result of a number of studies of the effect of the system. The report also summarizes the result of some other studies of similar computerized conferencing systems. The report gives information about how much KOM (the Swedish language version of COM) is used, what it is used for, which people use it, the user opinions about the advantages and disadvantages of the system, and it compares cost with other communication media. The Swedish language version of this report (report no C 10166) also contains as appendices full reports of those studies not presented in separate reports. Most of these appencices are not included in this English translation of the report.