Operating Systems of Mainframe computers Introduction An operating system (OS) is a set of computer programs that manage the hardware and software resources of a computer. An operating system processes raw system and user input and responds by allocating and managing tasks and internal system resources as a service to users and programs of the system. At the foundation of all system software, an operating system performs basic tasks such as controlling and allocating memory, prioritizing system requests, controlling input and output devices, facilitating networking, and managing file systems. Services provided by the Operating System 1.) Process management : Every program running on a computer, be it background services or applications, is a process. As long as a von Neumann architecture is used to build computers, only one process per CPU can be run at a time. 2.) Memory management : Current computer architectures arrange the computer''s memory in a hierarchical manner, starting from the fastest registers, CPU cache, random access memory and disk storage. 3.) Disk and file systems: All operating systems include support for a variety of file systems.Modern file systems are comprised of a hierarchy of directories. 4.) Networking: Most current operating systems are capable of using the TCP/IP networking protocols. 5.) Security: Many operating systems include some level of security. Security is based on the two ideas that: " The operating system provides access to a number of resources, directly or indirectly, such as files on a local disk, privileged system calls, personal information about users, and the services offered by the programs running on the system; " The operating system is capable of distinguishing between some requesters of these resources who are authorized (allowed) to access the resource, and others who are not authorized (forbidden). While some systems may simply distinguish between "privileged" and "non-privileged", systems commonly have a form of requester identity, such as a user name. Requesters, in turn, divide into two categories: " Internal security: an already running program. On some systems, a program once it is running has no limitations, but commonly the program has an identity which it keeps and is used to check all of its requests for resources. " External security: a new request from outside the computer, such as a login at a connected console or some kind of network connection. To establish identity there may be a process of authentication. 6.) Graphical user interfaces: Today, most modern operating systems contain Graphical User Interfaces (GUIs, pronounced goo-eez). 7.) Device drivers: A device driver is a specific type of computer software developed to allow interaction with hardware devices.
Mainframes Computers Mainframes (often colloquially referred to as Big Iron) are computers used mainly by large organizations for critical applications, typically bulk data processing such as census, industry/consumer statistics, ERP, and financial transaction processing. The term originated during the early years of computing and referred to the large mechanical assembly that held the central processor and input/output complex. Later the term was used to distinguish high-end commercial machines from less powerful units which were often contained in smaller packages. Today, this term refers primarily to IBM System z9 mainframes, the lineal descendants of the System/360, but it is also used for the lineal descendents of the Burroughs large systems and the UNIVAC 1100/2200 series mainframes. Mainframe operating systems that are still supported include: ״נ Burroughs MCP-- B5000,1961 to Unisys Clearpath/MCP,present : The MCP (Master Control Program) is the proprietary operating system of the Burroughs large systems including the Unisys Clearpath/MCP systems. ״נ IBM OS/360 -- IBM System/360, 1964 to IBM zSeries,present : OS/360 (Operating System/360) was a batch processing operating system developedy IBM for their then-new System/360 mainframe computer, announced in 1964. OS/360 was amongst the earliest operating systems to make direct access storage devices a prerequisite for its operation. ״נ UNIVAC EXEC 8 -- UNIVAC 1108, 1964, to Unisys Clearpath IX,present : The UNIVAC 1108 was the second member of Sperry Rand''s UNIVAC 1100 series of computers, introduced in 1964. A "Datacenter" variant of Windows Server 2003 is also available for some mainframe systems.
Published: October 22, 2007
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