[en] The gauge, apart of a measuring head, contains microcomputer ZX Spectrum, CRT tube monitor or a TV set and an interfacing circuit consisting of: 24 lines decoder for 1/0 devices, pulse amplitude to digit converter in the range 0-255, programmable counters seving as a real time clock and an interrupt circuit, as well as ERD-103 printer interface. The instrument measures the differential spectra of output pulses from proportional counter, corresponding to measured coal sample. Three measuring windows are then determined corresponding to: calcium excited radiation, iron excited radiation and backscattered radiation, and basing on it, the ash content is computed. The results of measurement are displayed on CRT tube monitor or on TV screen and printed by the printer. (author)