Mainframe computers are large systems that usually completely fill one or more rooms. Older makers: Burroughs, Honeywell, IBM, Sperry, Univac. Current makers: Unisys; of IBM compatible mainframes: Fujitsu Ltd., its US subsidiary Amdahl, Hitachi Ltd., IBM. IBM now dominates this market. Most other makers have been merged out of existence. Sperry and Univac merged into Sperry-Univac in 1955. Burroughs and Sperry merged into Unisys in 1986.
This category and its subcategories are for websites that cover the operating systems (OSs) and software products that run on IBM mainframes. Any sites also including mainframe hardware-related information belong in a subcategory of Computers/Hardware/Systems/IBM.

Only sites that do not fit in one subcategory go here. For example, many sites discuss z/VM and VSE/ESA, as both are often used together on one mainframe.

Mainframe application software developers are listed in Computers/Companies/Software_Development/Mainframes.

IBM

IBM mainframe computers are servers based on the processor instruction set of the System/360 introduced in the mid-1960s, much as today's Intel computers and processors are based on the 8086 used in the original 1981 IBM PC. This category covers the operating systems (OSs) and software products that run on IBM mainframes. Any sites also including mainframe hardware-related information belong in a subcategory of Computers/Hardware/Systems/IBM. On this page, OSs are arranged in two groups and levels: 1) Top group: issues spanning multiple IBM OSs. 2) Bottom group: specific IBM OSs, individual instances; there is only one OS of this name/type, with its own category.
This category and its subcategories are for websites that cover the operating systems (OSs) and software products that run on IBM mainframes. Any sites also including mainframe hardware-related information belong in a subcategory of Computers/Hardware/Systems/IBM.

Only sites that do not fit in one subcategory go here. For example, many sites discuss z/VM and VSE/ESA, as both are often used together on one mainframe.

Mainframe application software developers are listed in Computers/Companies/Software_Development/Mainframes.