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Information AboutExec 8 |
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BRIEF The Univac 1108 was a well-crafted electronic digital computer that emerged from the Univac Division of Sperry Rand Corporation in 1964. Instructions were fixed at 36 bits on word boundaries. Each instruction contained a six-bit operation code and, usually, a four-bit partial word designator, a four-bit register designator, a four-bit index register designator, a flag for index register incrementation, a flag for indirect addressing, and a 16-bit address offset field. Peripheral equipment transferred one 36-bit word at a time over one of sixteen I/O channels per CPU. Memory started at a minimum of 65,536 words and increased to a maximum of 262,144 words of magnetic core or thin film memory storage. CPUs maintained program state in a Processor State Register (PSR) that pointed to a user program's separate code and data blocks. There was no paging. Advances included a peripheral device called an MSA (Multiple Subsystem Adapter) that permitted byte-oriented peripherals to be connected to word channels, quarter-word addressing, a Test-and-Set Instruction, IOC (Input/Output Controller) subsystems that offloaded input/output responsibilities from CPUs, and ESI (Externally Specified Index) subsystem support that permitted efficient time-sharing services to be implemented. The hardware was advanced for the time and addressed scientific markets when IBM was targeting business markets. EXEC 8 was one of the first commercially successful symmetric multiprocessing operating systems. It supported simultaneous mixed workloads comprising batch, time-sharing and real-time. It supported one file system with a flat naming structure across many drums and/or spindles. It supported a well-received transaction processing system. Unisys continues to market and support systems founded on the original 1108 and EXEC 8 designs. SEE ALSO EXTERNAL LINK |
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