The vast majority of modern PCs are built according to a certain scheme called computer architecture - a system of hardware (physical) and software (mathematical and logical) tools that allow you to program and perform the necessary user tasks. Computer architecture is external, reflecting the composition and interaction of the entire peripheral system, and internal, in which the system of functioning of the constituent elements of the computer itself is enclosed.
The basis of the design and current computers is laid backbone-modular principle. The practical essence of this principle is that the user can shape the architecture of the computer and upgrade it, thanks to the compatibility and unification of computer components. The modular principle is supplemented by the main, or as it is also called, the bus principle of data exchange between modules and computer nodes. These two principles form another principle of creating modern computers - the principle of open architecture. Physically, the principle of open architecture is implemented by placing various devices on the motherboard (system) board: processor, video and sound cards, storage devices (RAM and ROM). Also, the main-modular principle of building a PC, the theoretical foundations of which were formulated in the middle of the last century by J. Von Neumann, involves the following principles of software communication between computer components:
- software control, which involves automatic execution by the processor of instructions and in a certain sequence;
- homogeneity of memory, providing for the storage of both commands and data in the same place;
- addressability, according to which the computer’s memory is created as a set of numbered cells accessed by the processor.
The main-modular principle of building a computer under consideration allows you to create a device configuration that is almost unique in parameters (of course, within the technical parameters of its components and their compatibility) and provide a main method for transmitting information between these parts. Such an exchange is carried out through the use of three different-sized tires (multi-wire lines). In this case, the bus capacity depends on the processor capacity. The data bus is designed to provide information transfer in two directions: from the processor to another computer device and from this device to the processor.
The address bus gives the processor access to the device’s memory location and works only in unidirectional mode - from the processor to the device.
The control bus transmits signals and commands that control the exchange of information and the synchronization of this exchange between different computer nodes. The physically considered main-modular principle of computer construction is realized thanks to the system bus, which, using the available slots (connectors), connects the computer devices together. System bus standards have changed with the development of technology. Now the most common type of system bus is the PCI bus. The system bus, together with the devices connected to it, form the backbone that the main module principle of computer construction mentions in its name.
Separate computer modules are physically connected to this trunk using controllers and adapters; their functioning as a program is provided by installing drivers that create conditions for the operating system to access the computer hardware system and vice versa.
The standard set of a modern computer includes:
- video adapter (for connecting the display);
- serial ports COM1 and COM2 (for connecting a mouse and modem);
- parallel port (for connecting a printer);
- keyboard controller.
As the backbone-modular principle of building a computer suggests, other peripheral modules and devices can be connected to the computer by installing additional adapters.