A low‐cost multichannel scaler and signal‐averaging system with user selectable channel widths ranging from 1 to 255 &mgr;s has been developed for molecular beam time‐of‐flight (TOF) experiments. It has the ability to collect up to 255 channels and has a programmable delay of up to 0.65 s. On‐board logic can accommodate a 15‐MHz count rate. Completely contained on a 7×2 3/4 ‐in. Apple II prototyping board (with the exception of a 5‐A, 5‐V external power supply), the interface fits into a peripheral port of the Apple II. The interface was tested by measuring the TOF distribution of Ar metastables from a supersonic nozzle beam source.