Review of the computer systems

All modern computer systems are built on three principles of John background of Neyman : programmatic management, homogeneity of memory and addressness.

The structure of the computer systems consists of three basic elements (see Picture 1.1, "Components of the computer systems") :

Processor

Carries out control after the actions of computer, and also performs the duty of processing of data according to the program. In the modern systems there can be one and more central processing units.

Conventional memory

The programs and data are kept in her. As a rule there is temporal (information is saved, while energised).

Input-outputs

Serve for communication of data between a computer and external surroundings consisting of subsidiary devices, bulk storage, of communication equipment, terminals, is included in the number of that.

System tire

The enumerated components of the computer system unite by means of system tire. It is structures and mechanisms, providing cooperation between a processor, conventional memory and input-outputs.

Picture 1.1 "Components of the computer systems"

Central processor extracts the program from memory, decodes and carries out commands, passes to the next command according to a current command.

At any time, the processor can execute only one program. Many modern operating systems are multitasking, at the same time can run multiple tasks.

Computer memory configuration is mainly determined by three parameters: volume, speed, cost.

Picture 1.2 . Classification of memory

Of particular importance is the main memory - it contains all the executable programs and data to them. The program can access any memory location in its address space. There are several types of address spaces: a real (physical memory corresponds to cells) and virtual (somehow projected onto the real address space).

Interaction with the IO devices can occur in three ways: a programmable input and output, input and output via an interrupt, direct memory access.