An Overview of the ISPL Computer System Design This paper explores the advantages of the concurrent design of the language, operating system, and machine (via microcode) to create an interactive programming laboratory. It describes the synergistic effect that the freedom to move and alter features from one of these domains to another has had on the design of this system (which has not been implemented). This freedom simplified both incremental compilation and the system's addressing structure, and centralized the communication mechanisms enabling the construction of hierarchical subsystems. It also suggested an important new concept for operating systems: separation of the scheduling from the maintenance functions in resource allocation. This separation enables incorporation of new scheduling algorithms (decision of what to do) without endangering the system integration (correctly performing the scheduling decisions). CACM February, 1973 Balzer, R. M. concurrent design, operating-system, scheduling, interprogram communication, incremental compilation, virtual addressing, debugging, hierarchical subsystems 4.0 4.13 4.22 4.30 4.32 4.41 4.42 6.20 CA730207 JB January 24, 1978 1:59 PM 1323 4 2541 1358 4 2541 1380 4 2541 1665 4 2541 1781 4 2541 1787 4 2541 1989 4 2541 2112 4 2541 2193 4 2541 2326 4 2541 2477 4 2541 2534 4 2541 2541 4 2541 2541 4 2541 2594 4 2541 2698 4 2541 2733 4 2541 2820 4 2541 3004 4 2541 3073 4 2541 3155 4 2541 2541 5 2541 2541 5 2541 2541 5 2541 3186 5 2541 799 5 2541