A Brief History of Computers (Cont.)

IBM System/360 Computers (1960s)
In 1964, after investing $5 billion, IBM made a bold move with the announcement of the System/360 with various models. The clock rate, range of memory sizes, and approximate price for only the processor and memory of average size of the four models are given next:

  1. Model 40: 1.6 MHz, 32 KB - 256 KB, $225K;
  2. Model 50: 2.0 MHz, 128 KB - 256 KB, $550K;
  3. Model 65: 5.0 MHz, 256 KB - 1 MB, $1.2M; and
  4. Model 75: 5.1 MHz, 256 KB - 1 MB, $1.9M.

Adding I/O devices typically increased the price by factors of 1.8 to 3.5. IBM bet its company on the success of a computer family, and IBM won. The System/360 and its successors dominated the large computer market. The IBM System/370 was a model range of IBM mainframes announced in 1970 as the successors to the System/360 family.

In 1965, Digital Equipment Corporation (DEC) unveiled the PDP-8, the first commercial minicomputer, a computer smaller than a mainframe, but larger than a microcomputer. It was a breakthrough in low-cost design, allowing DEC to offer a computer for under $20K. DEC was acquired in 1998 by Compaq, which merged with Hewlett-Packard in 2002.