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Unit Control Block
In IBM mainframe operating systems from the OS/360 and successors line, a Unit Control Block (UCB) is a memory structure, or a ''control block'', that describes any single input/output peripheral device (''unit''), or an ''exposure'' (alias), to the operating system. Certain data within the UCB also instructs the Input/Output Supervisor (IOS) to use certain closed subroutines in addition to normal IOS processing for additional physical device control. Some other operating systems have similar structures. Overview During initial program load (IPL) of current MVS systems, the Nucleus Initialization Program (NIP) reads necessary information from the I/O Definition File (IODF) and uses it to build the UCBs. The UCBs are stored in system-owned memory, in the Extended System Queue Area (ESQA). After IPL completes, UCBs are owned by Input/Output Support. Some of the data stored in the UCB are: device type (e.g. disk, tape, printer, terminal), address of the device (such as ''1002'' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
IBM Mainframe
IBM mainframes are large computer systems produced by IBM since 1952. During the 1960s and 1970s, IBM dominated the large computer market. Current mainframe computers in IBM's line of business computers are developments of the basic design of the IBM System/360. First and second generation From 1952 into the late 1960s, IBM manufactured and marketed several large computer models, known as the IBM 700/7000 series. The first-generation 700s were based on vacuum tubes, while the later, second-generation 7000s used transistors. These machines established IBM's dominance in electronic data processing ("EDP"). IBM had two model categories: one (701, 704, 709, 7030, 7090, 7094, 7040, 7044) for engineering and scientific use, and one (702, 705, 705-II, 705-III, 7080, 7070, 7072, 7074, 7010) for commercial or data processing use. The two categories, scientific and commercial, generally used common peripherals but had completely different instruction sets, and there were incompatibiliti ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hard Disk Drive
A hard disk drive (HDD), hard disk, hard drive, or fixed disk is an electro-mechanical data storage device that stores and retrieves digital data using magnetic storage with one or more rigid rapidly rotating platters coated with magnetic material. The platters are paired with magnetic heads, usually arranged on a moving actuator arm, which read and write data to the platter surfaces. Data is accessed in a random-access manner, meaning that individual blocks of data can be stored and retrieved in any order. HDDs are a type of non-volatile storage, retaining stored data when powered off. Modern HDDs are typically in the form of a small rectangular box. Introduced by IBM in 1956, HDDs were the dominant secondary storage device for general-purpose computers beginning in the early 1960s. HDDs maintained this position into the modern era of servers and personal computers, though personal computing devices produced in large volume, like cell phones and tablets, rely on ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Z/OS
z/OS is a 64-bit operating system for IBM z/Architecture mainframes, introduced by IBM in October 2000. It derives from and is the successor to OS/390, which in turn was preceded by a string of MVS versions.Starting with the earliest: * OS/VS2 Release 2 through Release 3.8 * MVS/System Extensions (MVS/SE) * MVS/System Product (MVS/SP) Version 1 * MVS/System Product Version 2 (MVS/Extended Architecture, MVS/XA) * MVS/System Product Version 3 (MVS/Enterprise Systems Architecture, MVS/ESA) * MVS/ESA SP Version 4 * MVS/ESA SP Version 5 Like OS/390, z/OS combines a number of formerly separate, related products, some of which are still optional. z/OS has the attributes of modern operating systems, but also retains much of the older functionality originated in the 1960s and still in regular use—z/OS is designed for backward compatibility. Major characteristics z/OS supportsSome, e.g., TSO/E, are bundled with z/OS, others, e.g.,CICS, are separately priced. stable mainframe fac ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
IBM DS8000 Series
The IBM DS8000 series (early IBM System Storage DS8000 series) is an IBM storage media platform with hybrid flash and hard disk storage for IBM mainframes and other enterprise grade computing environments. Description This series formerly designed as line of cabinet-size solutions, prior to more compact and affordable rack-mount DS6000 series. In 2015 the DS6000 line were discontinued, and the all-flash entry-level DS8882F model was released as rack-mount successor of DS6000 line. All IBM DS storage lines based on a IBM Power CPUs and use an IBM Power Systems servers as controllers. Models * TotalStorage models: ** DS8100 - released in 2004 *** Dual 2-core POWER5+-based controllers *** Can contain up to 384 drives ( Fibre Channel or SATA) ** DS8300 - released in 2004 *** Dual 4-core POWER5+-based controllers (based on p570 servers) *** Can contain up to 1024 drives (Fibre Channel or SATA) * System Storage models: **DS8100 Turbo - released in 2006 **DS8300 Turbo - release ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Workload Manager
In IBM mainframes, Workload Manager (WLM) is a base component of MVS/ESA mainframe operating system, and its successors up to and including z/OS. It controls the access to system resources for the work executing on z/OS based on administrator-defined goals. Workload Manager components also exist for other operating systems. For example, an IBM Workload Manager is also a software product for AIX operating system. Workload Manager On a mainframe computer many different applications execute at the same time. The expectations for executing work are consistent execution times and predictable access to databases. On z/OS the Workload Manager (WLM) component fulfills these needs by controlling work's access to system resources based on external specifications by the system administrator. The system administrator classifies work to service classes. The classification mechanism uses work attributes like transaction names, user identifications or program names which specific applications ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Backward Compatibility
Backward compatibility (sometimes known as backwards compatibility) is a property of an operating system, product, or technology that allows for interoperability with an older legacy system, or with input designed for such a system, especially in telecommunications and computing. Modifying a system in a way that does not allow backward compatibility is sometimes called " breaking" backward compatibility. A complementary concept is forward compatibility. A design that is forward-compatible usually has a roadmap for compatibility with future standards and products. A related term from programming jargon is hysterical reasons or hysterical raisins (near-homophones for "historical reasons"), as the purpose of some software features may be solely to support older hardware or software versions. Usage In hardware A simple example of both backward and forward compatibility is the introduction of FM radio in stereo. FM radio was initially mono, with only one audio channel represented ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
IBM 3850
The IBM 3850 Mass Storage System was an online tape library used to hold large amounts of infrequently accessed data. It was one of the earliest examples of nearline storage. History Starting in the late-1960s IBM's lab in Boulder, Colorado began development of a low-cost mass storage system based on magnetic tape cartridges. The tapes would be accessed automatically by a robot (known as an ''accessor'') and fed into a reader/writer unit that could work on several tapes at the same time. Originally the system was going to be used as a directly attached memory device, but as the speed of computers grew in relation to the storage, the product was re-purposed as an automated system that would offload little-used data from hard disk systems. Known internally as ''Comanche'' while under development, IBM management found a number of niche uses for the concept, and announced it officially as the IBM 3850 on October 9, 1974. After more than a decade (comparable to the IBM 2321 Data Cel ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Channel I/O
In computing, channel I/O is a high-performance input/output (I/O) architecture that is implemented in various forms on a number of computer architectures, especially on mainframe computers. In the past, channels were generally implemented with custom devices, variously named channel, I/O processor, I/O controller, I/O synchronizer, or ''DMA controller''. Overview Many I/O tasks can be complex and require logic to be applied to the data to convert formats and other similar duties. In these situations, the simplest solution is to ask the CPU to handle the logic, but because I/O devices are relatively slow, a CPU could waste time (in computer perspective) waiting for the data from the device. This situation is called 'I/O bound'. Channel architecture avoids this problem by processing some or all of the I/O task without the aid of the CPU by offloading the work to dedicated logic. Channels are logically self-contained, with sufficient logic and working storage to handle I/O tasks. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Disk Buffer
In computer storage, disk buffer (often ambiguously called disk cache or cache buffer) is the embedded memory in a hard disk drive (HDD) or solid state drive (SSD) acting as a buffer between the rest of the computer and the physical hard disk platter or flash memory that is used for storage. Modern hard disk drives come with 8 to 256 MiB of such memory, and solid-state drives come with up to 4 GB of cache memory. Since the late 1980s, nearly all disks sold have embedded microcontrollers and either an ATA, Serial ATA, SCSI, or Fibre Channel interface. The drive circuitry usually has a small amount of memory, used to store the data going to and coming from the disk platters. The disk buffer is physically distinct from and is used differently from the page cache typically kept by the operating system in the computer's main memory. The disk buffer is controlled by the microcontroller in the hard disk drive, and the page cache is controlled by the computer to which that ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tape Drive
A tape drive is a data storage device that reads and writes data on a magnetic tape. Magnetic tape data storage is typically used for offline, archival data storage. Tape media generally has a favorable unit cost and a long archival stability. A tape drive provides sequential access storage, unlike a hard disk drive, which provides direct access storage. A disk drive can move to any position on the disk in a few milliseconds, but a tape drive must physically wind tape between reels to read any one particular piece of data. As a result, tape drives have very large average access times. However, tape drives can stream data very quickly off a tape when the required position has been reached. For example, Linear Tape-Open (LTO) supports continuous data transfer rates of up to 360 MB/s, a rate comparable to hard disk drives. Design Magnetic tape drives with capacities of less than one megabyte were first used for data storage on mainframe computers in the 1950s. , capaci ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
OS/360
OS/360, officially known as IBM System/360 Operating System, is a discontinued batch processing operating system developed by IBM for their then-new System/360 mainframe computer, announced in 1964; it was influenced by the earlier IBSYS/IBJOB and Input/Output Control System (IOCS) packages for the IBM 7090/7094 and even more so by the PR155 Operating System for the IBM 1410/ 7010 processors. It was one of the earliestJust a few years after Atlas Supervisor, Burroughs MCP and GECOS operating systems to require the computer hardware to include at least one direct access storage device. Although OS/360 itself was discontinued, successor operating systems, including the virtual storage MVS and the 64-bit z/OS, are still run and maintain application-level compatibility with OS/360. Overview IBM announced three different levels of OS/360, generated from the same tapes and sharing most of their code. IBM eventually renamed these options and made some significant design changes: ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Operating System
An operating system (OS) is system software that manages computer hardware, software resources, and provides common services for computer programs. Time-sharing operating systems schedule tasks for efficient use of the system and may also include accounting software for cost allocation of processor time, mass storage, printing, and other resources. For hardware functions such as input and output and memory allocation, the operating system acts as an intermediary between programs and the computer hardware, although the application code is usually executed directly by the hardware and frequently makes system calls to an OS function or is interrupted by it. Operating systems are found on many devices that contain a computer from cellular phones and video game consoles to web servers and supercomputers. The dominant general-purpose personal computer operating system is Microsoft Windows with a market share of around 74.99%. macOS by Apple Inc. is in second place (14.84%), and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
