The basics of digital technology are set out in an accessible form. Number systems, principles of information coding, elements of logic algebra are briefly considered. Diagrams of main units of digital devices and their basic elements are given. The description is based on the example of promising series (as of 2016, series 155, 176, 561 are not promising, but they can be successfully replaced with more modern analogues, for example, series 1554, etc.) of digital integrated circuits of wide application, which are preferable in the design of digital devices in amateur radio practice.