Presentation of information in the computer: examples of use

If a person studies computer technology not superficially, but seriously enough, he must certainly know about what forms of information representation exist in the computer. This issue is one of the most fundamental, since not only the use of programs and operating systems, but programming itself is based in principle on precisely these elements.

Lesson "Presentation of information in the computer": the basics

In general, a computer technique in how it perceives information or commands, converts them into file formats and gives the user a ready-made result, somewhat different from the generally accepted concepts.

The fact is that all existing systems are based on only two logical operators - "true" and "false" (true, false). In a simpler sense, this is "yes" or "no."

It is clear that the words computer technology does not understand, therefore, at the dawn of the development of computer technology, a special digital system with a conditional code was created, in which the unit corresponds to the statement, and zero to the negation. This is how the so-called binary representation of information in the computer appeared. Depending on the combinations of zeros and ones, the size of the information object is also determined .

The smallest unit of measurement for this type of size is a bit-a bit that can be either 0 or 1. But modern systems with such small values do not work, and practically all methods of presenting information in a computer are reduced to using eight bits at once, which in sum Make up a byte (2 to the eighth power). Thus, in one byte, you can encode any character from 256 possible ones. And it is the binary code that is the basis of the foundations of any information object. Further it will be clear how it looks in practice.

Informatics: presentation of information in the computer. Fixed-point numbers

Since the speech originally came about the numbers, let us consider how the system perceives them. Representation of numerical information in a computer today can be conditionally divided into processing numbers with a fixed and floating point. The first type can also include ordinary integers, which have a zero after the comma.

It is believed that numbers of this type can occupy 1, 2 or 4 bytes. The so-called main byte is responsible for the sign of the number, with a zero for the positive sign, and one for the negative. Thus, for example, in a 2-byte representation, the range of values for positive numbers is in the range from 0 to 2 ¹⁶ -1, which is 65535, and for negative numbers from -2-15 to 2 ¹⁵ -1, which is equal to the numeric range from -32768 to 32767.

Floating-Point Representation

Now consider the second type of numbers. The fact is that the school curriculum on the topic "Presentation of information in the computer" (9th grade) does not deal with floating-point numbers . Operations with them are quite complex and are used, for example, when creating computer games. By the way, a little distracting from the topic, it is worth saying that for modern graphics accelerators one of the main performance indicators is the speed of operations with precisely these numbers.

Here an exponential form is used, in which the position of the comma may vary. As the basic formula showing the representation of any number A, the following is accepted: A = m _{A *} q ^P , where m _A is the mantissa, q ^P is the base of the number system, and P is the order of the number.

The mantissa must meet the requirement q ^-1 ≤ | m _A | <1, that is, it must be a proper binary fraction containing a digit after the decimal that is different from zero, and the order is an integer. And any normalized decimal number can be easily represented in an exponential form. And the numbers of this type are 4 or 8 bytes in size.

For example, the decimal number 999,999 according to the formula with the normalized mantissa will look like 0.999999 _* 10 ³ .

Displaying text data: a bit of history

Most users of computer systems still use test information. And the presentation of textual information in the computer corresponds to the same principles of binary code.

However, due to the fact that a lot of languages can be found in the world today, special encoding systems or code tables are used to represent text information. With the advent of MS-DOS, the core standard was the CP866 encoding, and Apple's computers used their own Mac standard. At that time for the Russian language was introduced a special encoding ISO 8859-5. However, with the development of computer technology, new standards had to be introduced.

Types of encodings

So, for example, in the late 90-ies of the last century there was a universal encoding Unicode, which could work not only with text data, but also with audio and video. Its peculiarity was that one bit was assigned to one character, but two.

A little later, there were other varieties. For Windows systems, the encoding of the CP1251 is the most used, but for the same Russian language and still uses KOI-8P - encoding, appeared in the late 70's, and in the 80's actively used even on UNIX-systems.

The very presentation of textual information in the computer is based on the ASCII table, which includes the basic and extended parts. The first includes codes from 0 to 127, the second - from 128 to 255. However, the first codes of the range 0-32 are not assigned to the symbols that are assigned to the keys of the standard keyboard, but to the function buttons (F1-F12).

Graphic images: basic types

As for graphics, which is actively used in the modern digital world, there are nuances. If you look at the presentation of graphic information in your computer, you should first look at the main types of images. Among them are two main types - vector and bitmap.

Vector graphics are based on the use of primitive forms (lines, circles, curves, polygons, etc.), text inserts and fills with a certain color. Raster images are based on the use of a rectangular matrix, each element of which is called a pixel. For each such element, you can set the brightness and color.

Vector images

Today, the use of vector images has a limited scope. They are good, for example, when creating drawings and technical schemes or for two-dimensional or three-dimensional models of objects.

Examples of stationary vector forms can be formats like PDF, WMF, PCL. For moving forms, the MacroMedia Flash standard is generally used. But if you talk about quality or perform more complex operations than the same scaling, it's better to use raster formats.

Bitmap Images

With raster objects, the situation is much more complicated. The fact is that presenting information in a matrix-based computer involves using additional parameters-the color depth (the quantitative expression of the number of colors in the palette) in bits, and the size of the matrix (the number of pixels per inch, referred to as DPI).

That is, the palette can consist of 16, 256, 65536 or 16777216 colors, and the matrix may vary, although the most common resolution is 800x600 pixels (480,000 pixels). By these measures, you can determine the number of bits required to store the object. To do this, we first use the formula N = 2 ^I , in which N is the number of colors, and I is the color depth.

Then the amount of information is calculated. For example, calculate the file size for an image containing 65536 colors, and a matrix of 1024x768 pixels. The solution is as follows:

• I = log ₂ 65536, which is 16 bits;
• Number of pixels 1024 _* 768 = 786 432;
• The amount of memory is 16 bits _* 786 432 = 12 582 912 bytes, which corresponds to 1.2 MB.

Types of audio: the main directions of synthesis

The presentation of information in a computer called audio is subject to the same basic principles as described above. But, as for any other kind of information objects, additional characteristics are also used to represent the sound.

Unfortunately, high-quality sound and reproduction appeared in computer technology in the very last turn. However, if with reproduction still things were still somehow, then the synthesis of a really sounding musical instrument was practically impossible. Therefore, some record companies have introduced their own standards. Today FM-synthesis and tabular-wave method are most widely used.

In the first case, it is implied that any natural sound that is continuous can be decomposed into a certain sequence (combination) of the simplest harmonics with the help of the method of discretization and produce information representation in the computer's memory based on the code. For playback, the reverse process is used, but in this case the loss of some components is inevitable, which is displayed on the quality.

In table-wave synthesis it is assumed that there is a pre-created table with examples of sounding live instruments. Such examples are called samples. In this case, MIDI commands (Musical Instrument Digital Interface) are often used for playback, which perceive the type of instrument, pitch, duration of sound, intensity and dynamics of changes, environmental parameters and other characteristics from the code. Due to this, this sound is closely approximated to the natural one.

Modern formats

If earlier the WAV standard was taken as the basis (actually, the sound itself is represented as a wave), over time it became very inconvenient, at least because such files took up too much space on the storage medium.

Over time, technologies have appeared that make it possible to compress such a format. Accordingly, the formats themselves have changed. The most famous today can be called MP3, OGG, WMA, FLAC and many others.

However, until now the main parameters of any audio file remain the sampling frequency (the standard is 44.1 kHz, although one can meet the values both above and below) and the number of signal levels (16 bits, 32 bits). In principle, such digitization can be interpreted as the representation of information in a computer of sound type based on the primary analog signal (any sound in nature is initially analog).

Video Submission

If the problems with the sound were solved quickly enough, then with the video everything went not so smoothly. The problem was that a clip, movie or even a video game is a combination of video and sound. It would seem, which is easier, than to combine moving graphic objects with a scale? As it turned out, this became a real problem.

Here the point is that from the technical point of view, the first frame of each scene, called the key frame, should first be memorized, but only then to preserve the differences (difference frames). And, the most sad, digitized or created videos turned out to be so large that it was simply impossible to store them on a computer or removable media.

The problem was solved when the AVI format appeared, which is a kind of universal container consisting of a set of blocks in which arbitrary information can be stored, even compressed in different ways. Thus, even files of the same AVI format can differ significantly among themselves.

And today you can meet quite a few other popular video formats, but for all of them also use their own indicators and parameter values, the main one of which is the number of frames per second.

Codecs and Decoders

Representation of information in the computer in the video plan is impossible to imagine without the use of codecs and decoders used to compress the initial contents and decompress during playback. Their very name suggests that some encode (compress) the signal, the second - on the contrary - unpack.

They are responsible for the contents of containers of any format, as well as determine the size of the final file. In addition, an important role is played by the resolution parameter, as it was indicated for raster graphics. But today you can even find UltraHD (4k).

Conclusion

If we sum up some of the above, we can only note that modern computer systems initially work exclusively on the perception of binary code (they simply do not understand the other). And on its use is based not only the presentation of information, but also all known programming languages today. Thus, initially, in order to understand how all this works, it is necessary to delve into the essence of the application of sequences of ones and zeros.