This textbook is a record of lectures in computer science delivered by applicants to Kaliningrad State University . It is fairly balanced, and its individual sections are interconnected .. The educational material is designed for those who are not familiar with either computer or programming, but will certainly be useful to all schoolchildren. When working with this book, a computer is not necessary, but desirable. The first part "Computer" can be used to obtain basic knowledge before computer practice, the second part "Programming" - before programming in Pascal or another procedural language. The course can be used not only by students preparing for the entrance exam in computer science . These lectures will be useful both in teaching computer science at school and in teaching computer science at universities. It is not excluded to work with material in self-education. The content corresponds to the recommendations of the Ministry of Education of the Russian Federation for entrance examinations in computer science