An example of concurrent program design

A PC-AT with a MS-DOS operating system was used for real-time process automation. A sequential switching among processes was selected, because the operating system is not re-entrant. The language Modula-2 was chosen because it is possible to implement well known coroutines. Finally, the software module Monitor was introduced, which controls the cooperation of quasi-concurrent executable processes. The definition of the Monitor primitives is described. An illustrative example of real-time application is given and some advantages of the proposed system are emphasized.