IBM System/360
The IBM System/360 (S/360) is a groundbreaking family of computer systems announced by IBM on April 7, 1964. This versatile system was delivered between 1965 and 1978 and marked a revolutionary step in computing by being the first family of computers designed to cover both commercial and scientific applications while offering a comprehensive range of sizes, from small, entry-level machines to large mainframes.
Architecture and Design
The architecture of the System/360 was its defining characteristic. It was designed to distinguish between architecture and implementation, which allowed IBM to release a suite of compatible designs across various price points. A highlight of the system was its introduction of IBM's Solid Logic Technology (SLT), which packed more transistors onto a circuit card, enabling more powerful yet smaller computers. This was a significant technological advancement, although the system did not initially include integrated circuits, which IBM considered too immature at the time.
The instruction set was implemented predominantly using microcode, which employed an 8-bit byte addressing with capabilities for fixed-point binary, fixed-point decimal, and hexadecimal floating-point calculations.
Key Figures and Development
The chief architect behind the System/360 was Gene Amdahl, with the project being managed by Fred Brooks. They reported to Thomas J. Watson Jr., the then-chairman of IBM. The commercial release was piloted by John R. Opel, who managed the launch of IBM's System/360 mainframe family in 1964.
Models and Legacy
The System/360’s family included a variety of models designed for different needs and budget levels. The IBM System/360 Model 30 represented the low-end of the family, while models like the IBM System/360 Model 91 were designed for more demanding computing tasks. The IBM System/360 Model 67 was particularly notable for including features like virtual memory, which were not present in other models of the series.
The System/360 set a standard for compatibility and upgradability that would influence subsequent IBM systems, including the IBM System/370. Its architecture became the model independent architecture for sophisticated computing systems.
Operating Systems and Software
The System/360 also gave rise to innovative operating systems such as the OS/360 and DOS/360, which were the first members of a sequence of operating systems for IBM mainframes. These operating systems laid the groundwork for future developments in software for mainframe computers.
The IBM Basic assembly language was another significant development associated with the System/360, providing an assembly language for this mainframe series and its successors.