Minicomputers were developed in the 1960's, as smaller and less-expensive computers, fitting in one corner of a room. They also needed air conditioning, but they could be put where they were needed, and they could be operated directly by their owners or users. They ran either as "batch" or "time-shared" systems, like the DEC system shown on this poster; or as dedicated systems like the PDP-11/20 on display. By the 1970's the increased use of time-sharing and of minicomputers, falling costs, and increased computing power, suggested to some the idea that computing could become "personal".

Minicomputer companies grew throughout the 1970's and 80's. But the 1970's microprocessor became the microcomputer of the mid-1970's and part of the personal computer "revolution". Microcomputers replaced the mini's at the low end, and high-end minis became indistinct from mainframes. The term "minicomputer" fell out of use sometime during the 1990's. DEC was bought by personal computer maker Compaq, which was later bought by HP, an electronic instrument company in the 1970's and earlier.

The photo, from a 1970 DEC brochure, shows a PDP-11 with paper tape, magnetic tape, disk storage and memory devices in four vertical "racks". The person on the right is at a printer; on the left, at a DEC printing terminal. This system would be in an air-conditioned room and require many kilowatts of cooling and electric power. By the late 1970’s, much of this storage and printing technology was in use by microcomputers.