Inspecting hardware on a regular basis to ensure it stays in good running order. Preventive maintenance generally implies taking the equipment out of operation during the maintenance period. In the 1960s and 1970s, preventive maintenance took hours every week or every month and was performed by a field engineer.
Starting in the 1980s, computers began to run without breaking down for weeks and months on end, and preventive maintenance became less of an issue over time. Today, electronic devices are rarely taken out of operation on a regular basis. The only exception is the periodic cleaning of automatic feeders and paper paths in high-volume printers and scanners. See remedial maintenance
and percussive maintenance