A simple and low‐cost microcomputer‐based data accumulation system was developed for use with the Varian E‐line series of EPR spectrometers. The hardware is based on the Apple II europlus microcomputer with 12K of read‐only memory, 48K of random access memory, and an 8‐bit A/D and D/A converter. The software has been written in MOTOROLA assembler language and is used to collect data from spectral scans in single‐scan and multiscan modes, store and recall those data on or from floppy disks, scale data, display data on a high‐resolution graphic VDU, and output data to the spectrometer X–Y recorder. The microcomputer controls part of the spectrometer functions during the scans. The software described is the first part of a whole spectral analysis programs set.