Theme: Peripherals

THEME: Peripherals.
It is impossible to imagine a computer without means of communication with a person or means of interfacing with external control objects. Such tools are necessary for downloading programs and data, uploading the results obtained, storing huge amounts of information, correcting computer operation by the user, as well as for direct control of production processes and objects. All these functions are assigned to a variety of peripheral devices (PU), which serve to transform the ways of presenting information suitable for a person and used in a computer, to control input / output and organize information storage, regardless of the presence of power.
Thus, I consider it important to systematize and structure information about the peripheral devices of computers, and then determine the significance of the place of peripheral devices in electronic computers.

1. Interaction of PU and computer

1.1 Definition of peripherals

Peripheral, or external, devices got their name in the 1960s, when the processor and RAM were placed in rack cabinets, forming a kind of “center”, and the rest of the devices, mostly electromechanical, were at some distance from it, i.e. on the periphery. But modern PUs are located both inside the computer case and outside, depending on the type of device and its interaction with objects in the outside world. A peripheral device is an additional auxiliary device external to the central processor and main memory, designed to input and / or output information to a computer and store data, and expanding its functionality. That is, it is by and large an optional device for the operation of a computer, but in most cases it is necessary for the implementation of certain user tasks. There are four types of peripherals:

1. 
   input devices;
   
2. 
   output devices;
   
3. 
   input-output devices;
   
4. 
   data storage devices. Some PUs, called internal, are mounted in the same case with the computer (for example, hard disk, sound card, network card), while others, called external, are outside the case (for example, keyboard, mouse, printer) and are connected to it using a wired or wireless connection. Peripherals are connected to the central part of the computer through an interface, so it is important to give several definitions of this important concept.
   

1.2 Interface

Interface (interface) - a set of tools and rules that ensure the interaction of devices of a computer or information processing system and (or) programs. In addition to these standard definitions, it is convenient to use one more that expands and refines the above. An interface is a set of means and rules that provide interaction:

1. 
   between different nodes of a computer system (hardware interface);
   
2. 
   between programs (software interface);
   
3. 
   between hardware and software (hardware and software interface);
   
4. 
   between a person and a computer (human-machine interface).
   

Peripheral devices with such a type of human-machine interface as the USB HID class seem to be very promising for use. USB HID is a class of USB devices that connect to a computer for human interaction. This class includes devices such as keyboard, mouse, game controller.

1.3 Tires

So, to connect a peripheral device, you must first provide a hardware interface. In a computer, it is implemented by I / O buses. Modern computers contain two types of buses: a) the system bus that connects the central processing unit to the main memory; b) multiple I/O buses connecting various peripherals to the system bus and processor via a bridge The bus is a subsystem for transmitting data both internally computer and beyond. Unlike a point-to-point connection, which is designed to connect only two devices, a bus, by using the same set of wires, can provide a logical connection for several peripheral devices. The main difference between peripherals is the way they are connected - internal or external. The first is implemented using internal buses, represented by internal connectors (slots) on the system board, the second method is implemented by external buses, represented by external connectors (ports). However, in the general case, an external peripheral device connection scheme is used.
Next, we should recall the need for a hardware-software interface, i.e. peripheral controller driver.

1.4 Drivers

Driver is a computer software with the help of which another software (operating system) gains access to the hardware of some, in our case, peripheral device. Typically, operating systems ship with drivers for key hardware components that the system cannot function without. However, some devices (such as a video card or printer) may require special drivers, usually provided by the device manufacturer.