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In the 1970s, Burroughs Corporation was organized into three divisions with very different product line architectures for high-end, mid-range, and entry-level business computer systems. Each division's product line grew from a different concept for how to optimize a computer's instruction set for particular programming languages. The Burroughs Large Systems Group designed large mainframes using stack machine instruction sets with dense instruction syllables〔E.g., 12-bit for B5000, 8-bit for B6500〕 and 48-bit data words. The first such design was the B5000 in 1961. It was optimized for running ALGOL 60 extremely well, using simple compilers. It evolved into the B5500. Subsequent major redesigns include the B6500/B6700 line and its successors, and the separate B8500 line. 'Burroughs Large Systems' referred to all of these product lines together, in contrast to the COBOL-optimized Medium Systems (B2000, B3000, B4000) or the flexible-architecture Small Systems (B1000). Founded in the 1880s, Burroughs was the oldest continuously operating entity in computing, but by the late 1950s its computing equipment was still limited to electromechanical accounting machines such as the Sensimatic; as such it had nothing to compete with its traditional rivals IBM and NCR who had started to produce larger-scale computers, or with recently founded Univac. While in 1956 it branded as the B205 a machine produced by a company it bought, its first internally developed machine, the B5000, was designed in 1961 and Burroughs sought to address its late entry in the market with the strategy of a completely different design based on the most advanced computing ideas available at the time. While the B5000 architecture is dead, it inspired the B6500 (and subsequent B6700 & B7700). Computers using that architecture are still in production as the Unisys ClearPath Libra servers which run an evolved but compatible version of the MCP operating system first introduced with the B6700. The third and largest line, the B8500,〔〔 had no commercial success. In addition to a proprietary CMOS processor design Unisys also uses Intel Xeon processors and runs MCP, Microsoft Windows and Linux operating systems on their Libra servers. ==B5000== The first member of the first series, the B5000,〔 was designed beginning in 1961 by a team under the leadership of Robert (Bob) Barton. It was a unique machine, well ahead of its time. It has been listed by the influential computing scientist John Mashey as one of the architectures that he admires the most. "I always thought it was one of the most innovative examples of combined hardware/software design I've seen, and far ahead of its time."〔 〕 The B5000 was succeeded by the B5500〔 (which used disks rather than drum storage) and the B5700 (which allowed multiple CPUs to be clustered around shared disk). While there was no successor to the B5700, the B5000 line heavily influenced the design of the B6500, and Burroughs ported the Master Control Program (MCP) to that machine. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Burroughs large systems」の詳細全文を読む スポンサード リンク
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