The System/370 or S/370 was a mainframe architecture, IBM built in the 1970s. The System was mostly compatible with System/360, which IBM had built before. >Many applications coulds be re-used. The biggest change was that S/370 could handle virtual memory. The S/370 used tape drives and hard drives as mass storage device. The System/390 replaced the System/370 in the 1990s.