Concept
Midrange computers, or midrange systems, were a class of computer systems that fell in between mainframe computers and microcomputers. This class of machine emerged in the 1960s, with models from Digital Equipment Corporation (PDP line), Data General (NOVA), Hewlett-Packard (HP3000) widely used in science and research as well as for business - and referred to as minicomputers. IBM favored the term "midrange computer" for their comparable, but more business-oriented systems. System/3 was the first IBM midrange system (1969) System/32 (introduced in 1975) was a 16-bit single-user system also known as the IBM 5320. System/34 (1977) was intended to be a successor to both the 3 and the 32. System/38 (1979) was the first midrange system to have an integrated relational database management system (DBMS). The S/38 had 48-bit addressing, and ran the CPF operating system. System/36 (1983) had two 16-bit processors with an operating system that supported multiprogramming. AS/400 was introduced under that name in 1988, renamed eServer iSeries in 2000, and subsequently became the IBM System i in 2006. It runs the OS/400 operating system. IBM Power Systems were introduced in April 2008, a convergence of IBM System i and IBM System p. The main similarity of midrange computers and mainframes - they are both oriented for decimal-precision computing and high volume input and output (I/O), but most midrange computers have an (reduced and specially designed) internal architecture with limited compatibility to mainframes. The low-end mainframe can be more affordable and less powerful that a hi-end midrange system, but midrange system still was a "replacement solution" with another service process, different OS and internal architecture. The difference between similar-size Midrange and Supermini/Minicomputer - is a computing purposes: Super/mini oriented for float-point scientific computing, midrange - for decimal business-oriented computing, but without clear distinction border between classes.
