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| | IBM mainframe - Wikipedia, the free encyclopedia |
 | | IBM had two model categories: one (701, 704, 709, 7090, 7040) for engineering and scientific use, and one (702, 705, 7080, 7070, 7010) for commercial or data processing use. |
 | | IBM initially sold its computers without any software, expecting customers to write their own; and programs were manually initiated, one at a time. |
 | | IBM had difficulty getting customers to upgrade from the smaller machines to the mainframes because so much software had to be rewritten. |
| en.wikipedia.org /wiki/IBM_mainframe (993 words) |
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