Theme 1. Information. Computing systems. Units of information. Hardware

Any information (text, music, images, etc.) for its processing by the computer must be converted into a numeric form.

The calculation system defines the rules for writing numbers and executing arithmetic operations over them (+ - * /).

In computer science, three basic systems of calculation are used - binary, octal and hexadecimal.

Any information in the PC appears in the binary code. In particular, machine commands are represented by two characters 0 and 1 ("yes" and "no", "is" and "no").

These codes have two main fields: the operation field - the binary operation code and field address - the number of data cells over which this operation is performed and where to send the result of the operation.

The presentation of data and programs in binary form is conditioned by the principle of PC operation. It's almost instantaneous to determine if there is a voltage in a given cell (1) or not (0) on RAM; a dipole is "magnetized" or not on the HDD; the reflection of the laser beam is or not on the CD.

The octal computing system uses numbers from 0 to 7.

To write data in a PC memory, a hexadecimal encoding system is used, in which, except for numbers from 0 to 9, letters of the Latin alphabet are used: A = 10, B = 11, C = 12, D = 13 , E = 14, F = 15.

Between the decimal, binary and hexadecimal computing systems there is a unique match:

Example 1. Write the numbers 24 ₍₁₀₎ and 16 ₍₁₀₎ in the binary code. Make them and translate the result into a decimal number.

Adding two binary numbers:

Transmission from binary system to decimal:

Character encoding

To process the text information on a PC, each its symbol is encoded by some number. The correspondence between a set of letters and a number is called the character encoding. The character encoding table with 8-bit numbers is called ASCII (American Standard Coding for Information Interchange). The first part of the table (codes 0-127) includes signs, Arabic numerals, Latin alphabet, and is generally accepted by the whole world. In the second half of the table (codes 128-255), there is a national alphabet, as well as special characters.

Part of the code page 866 for MS-DOS

Example. Record the sequence of letters "ABC" in the binary code.

Units of measurement of information

Bit (binary digit) - a binary digit that accepts values 0 or 1, is the smallest unit of measurement of information.

A bit can also be represented as a cell (memory cell).

Binary elements that are grouped are called memory registers. This indicates the length of the register - the number of binary elements in the group.

Computer commands work not with separate bits, but with their registers.

Byte (byte) - eight consecutive bits, is the basic unit of measurement of computer information.

In eight binary discharges, there are 2 ⁸ = 256 integers (from 0 to 255), which is sufficient for the 8-bit designation of each large, small letter of the English and national alphabets, numbers, signs, etc.

Other units of information are also used, for example, the word 16 bits (2 bytes), the double word is 32 bits (4 bytes) and 64 bits (8 bytes), etc.

To measure large volumes of information, the following units of measurement (sets of bit) are used:

1 kilobyte (K) = 1024 = 2 ¹⁰ bytes (B) = 10 ³ B

1 megabytes (M) = 1048576 = 2 ²⁰ B = 2 ¹⁰ KB = 10 ⁶ B

1 Gigabyte (G) = 1073741824 = 2 ³⁰ B = 2 ²⁰ KB = 2 ¹⁰ MB = 10 ⁹ B

1 terabyte (T) = 2 ⁴⁰ B = 2 ³⁰ KB = 2 ²⁰ MB = 10 ¹² B

If one letter in ASCII code is 1 Byte, then the encyclopedia approximates approximately 120 MB, the newspaper 150 KB, person in 70 years of life says 10 GB.