Revision

Chapter I: information is the meaning received through the senses; a message is its material form; information should be valuable, complete and reliable; we divide information into analog (continuous) and discrete types. Coding is changing information into another form by a rule (uniform and non-uniform). The base of a number system is the number of digits; decimal, binary, octal and hexadecimal systems are positional. Addition, subtraction and multiplication are done in columns with carrying and borrowing. Converting to decimal is the sum of the expanded form; converting from decimal to another base is repeated division with remainders read from bottom to top; between 2, 8 and 16 we use triads and tetrads. A computer codes in binary: N = 2^m; 1 byte = 8 bits; 1 KB = 1024 bytes; speed = volume : time. Chapter II: information technology is the methods and means of working with information; network types are local, regional and global; the Internet is a network of networks with the protocol TCP/IP; the WWW is a system of web pages; a URL is a page address; a browser shows pages; a search system finds pages by keywords and the source must be checked; an email address is name@server; protection means updates, antivirus, strong passwords, caution and turning to adults. When revising, first recall the tables and formulas, then solve examples and check every result.