[en] For the quantitative nuclide analysis of γ-ray emitting samples measured with semiconductor detectors and evaluated by means of the NTA 1024 Hungarian multichannel analyzer on-line connected with the EMG 666 desk computer the program NIDAC has been developed. Measurement and analysis of spectra are carried out on-line and in a dialogue mode. The program is to rationalize the work in environmental surveillance. Therefore, the program determines nuclides and activities as well as derives data like specific activities etc. needed for reporting. A plot of results is available after the end of measurement within 2 minutes, at maximum. (author)