minicomputer, computer that was smaller, less expensive, and less powerful than a mainframe or supercomputer but more expensive and more powerful than a personal computer. Minicomputers were used for scientific and engineering computations, business transaction processing, file handling, and database management. Minicomputers as a distinct class of computers emerged in the late 1950s and reached their peak in the 1960s and ’70s before declining in popularity in the 1980s and ’90s. Their niche was filled by more powerful personal computers, workstations, and small or midsize servers.