Examples of mainframe computers include the IBM zSeries, System z9 and System z10 servers. IBM dominates the mainframe market with more than 90 percent market share. In addition to IBM machines, mainframes in use include the ClearPath Libra brand and the ClearPath Dorado from Unisys.
Hewlett-Packard manufactures mainframe systems known as NonStop. Groupe Bull makes the DPS, and Fujitsu markets its BS2000. The company's Fujitsu-ICL VME mainframes are available in Europe.
After introducing several models of mainframe computers in the 1940s and early 1950s, the IBM RAMAC 305 was introduced in 1956. It used 50 iron-coated revolving disks which accepted magnetically coded data. The process used by the RAMAC 305 significantly improved the state of data processing. IBM rolled out two of its most significant advances in computing in 1959. The 1401 Data Processing System was used for business, and the 1620 Data Processing System was used in science and engineering.
Modern mainframes can run several operating systems at once. Using virtual machines, mainframes run the various operating systems as if they were running on different computers. Virtual machine capability is available on personal computers, but runs much more easily on powerful mainframes. The computers can quickly change system capabilities without harming functionality. Mainframes are made to handle high volumes of data processing; they typically have significant memory for processing numerous computing tasks at once along with a large storage capacity.