which term means that an operating system can execute various processes simultaneously
Process (computing) Multitasking is a method to allow multiple processes to share processors (CPUs) and other system resources. Each CPU (core) executes a single task at a time. However, multitasking allows each processor to switch between tasks that are being executed without having to wait for each task to finish. Depending on the operating system implementation, switches could be performed when tasks perform input/output operations, when a task indicates that it can be switched, or on hardware interrupts.
SPMD In SPMD, multiple autonomous processors simultaneously execute the same program at independent points, rather than in the lockstep that SIMD imposes on different data. With SPMD, tasks can be executed on general purpose CPUs; SIMD requires vector processors to manipulate data streams. Note that the two are not mutually exclusive.