On Multiprogramming, Machine Coding, and Computer Organization The author feels that the interrupt feature which is available in most modern computers is a potent source of programming pitfalls and errors, and that it therefore may heavily contribute to the unreliability of programs making use of it. A programming scheme is presented which avoids the concept of the interrupt and permits the specification of concurrent (or pseudoconcurrent) activities in a supposedly more perspicuous manner. It is intended to serve as a basis for the construction of operating systems, which are prime examples of programs with concurrent activities. The scheme includes a set of basic instructions for the generation, termination, and synchronization of parallel processes. A set of routines representing these instructions and thereby simulating a hypothetical machine organization has been implemented and test on the IBM System/360. Two programs using these instructions, written in PL360, are presented. CACM September, 1969 Wirth, N. multiprogramming, parallelism, interrupt, input-output, computer organization, file handling, PL360 4.21 4.22 4.32 4.41 6.21 CA690901 JB February 15, 1978 5:14 PM 1380 4 1854 1458 4 1854 1523 4 1854 1552 4 1854 1603 4 1854 1693 4 1854 1698 4 1854 1747 4 1854 1748 4 1854 1781 4 1854 1805 4 1854 1828 4 1854 1828 4 1854 1854 4 1854 1854 4 1854 1854 4 1854 1854 4 1854 1860 4 1854 1877 4 1854 1877 4 1854 1960 4 1854 1960 4 1854 2060 4 1854 2150 4 1854 2187 4 1854 2317 4 1854 2319 4 1854 2377 4 1854 2377 4 1854 2378 4 1854 2342 4 1854 2376 4 1854 2379 4 1854 2424 4 1854 2482 4 1854 2497 4 1854 2558 4 1854 2618 4 1854 2625 4 1854 2632 4 1854 2632 4 1854 2704 4 1854 2723 4 1854 2738 4 1854 2740 4 1854 2741 4 1854 2840 4 1854 2867 4 1854 2941 4 1854 557 4 1854 3105 4 1854 3144 4 1854 3184 4 1854 1421 5 1854 1471 5 1854 1748 5 1854 1749 5 1854 1854 5 1854 1854 5 1854 1854 5 1854 1960 5 1854 1471 6 1854 1749 6 1854 1854 6 1854