A Modular Computer Sharing System An alternative approach to the design and organization of a general purpose interactive multiterminal computing system is presented. The system organization described is a conceptually simple arrangement of a bank of interchangeable computers, each of which is a memory/processor pair, that are assigned to process terminal jobs as they arrive. One of the computers serves as the master or control computer and supervises the collection and distribution of messages from and to the remote terminals. In the simplest form there is a disk drive for each connected terminal. A crosspoint switching network allows any such disk drive to be connected to any computer. Thus, while each active terminal user "occupies" a dedicated disk drive, he may share the computer with many other terminal users in a simple manner. The ratio of users to computers is dependent on both the size and power of the machines used and the computation requirements of the particular mix of users. This system organization is inherently a simpler and therefore more reliable approach to time-sharing computers and has the potential of a highly available system at relatively low cost. Economic configurations are possible for a range of systems sizes that span at least one order of magnitude. Finally, problem programs developed by remote terminal users can be run on a dedicated batch system if compatible computers are used. CACM October, 1969 Baskin, H. B. Horowitz, E. B. Tennison, R. D. Rittenhouse, L. E. multiple terminal systems, terminal oriented systems, multiple processor systems, high availability, conversational systems, general purpose time-sharing systems, real-time response system, modular constructed systems, modular computer-sharing systems, graphics, file switch, intercomputer communications, control computer, problem computer, roll-in, roll-out 6.21 CA691002 JB February 15, 1978 3:52 PM 1844 5 1844 1844 5 1844 1844 5 1844