What Is a Multitasking Operating System?

The so-called multi-program design refers to a method that allows multiple programs to enter the main memory of a computer system at the same time and run these programs. This multiprogramming system is also called a multitasking operating system. ^[1]

Since the mid-1960s, computer systems have entered the third generation of development. To

Single-user single-tasking operating system: It means that one computer can only be used by one user at a time. The user can only submit one job at a time, and one user can enjoy all the hardware and software resources of the system on his own. (Eg: MS-DOS, PC-DOS, CP / M)

Single-user multi-tasking operating system: A computer can only be used by one user at a time, but the user can run or submit multiple jobs at a time. (Eg: windows) (windows2000 and XP can have multiple users, why is it a single user? Although windows can set up multiple users, but only one user can enjoy all system resources at the same time, so windows can only It is a single-user operating system. Because "multi-user" is defined as: allowing multiple users to use the same host through their terminals and share various resources of the host system)

Multi-user and multi-tasking operating system: refers to a computer that can be used by multiple users at the same time and can perform multiple tasks submitted by multiple users (such as Unix / Linux, etc.)

The characteristics of a multitasking system can be summarized as follows:

(1) Multiple channels-there are more than two programs in main memory, and the processes corresponding to these programs are in one of three states: ready, running, and waiting at any time;

(2) Macro-parallel-from a macro perspective, these programs are being executed;

(3) Micro-serial-Micro-perspective, the processes corresponding to these programs are being executed alternately, because only one process can be executed on the processor (CPU) at any one time. ^[3]