6947glos.fm

Draft Document for Review April 7, 2004 6:15 pm

initial program load (IPL). (1) The initialization procedure that causes an operating system to commence operation. (2) The process by which a configuration image is loaded into storage at the beginning of a work day or after a system malfunction.

(3)The process of loading system programs and preparing a system to run jobs.

input/output (I/O). (1) Pertaining to a device whose parts can perform an input process and an output process at the same time. (2) Pertaining to a functional unit or channel involved in an input process, output process, or both, concurrently or not, and to the data involved in such a process. (3) Pertaining to input, output, or both.

input/output configuration data set (IOCDS). The data set in the S/390 processor (in the support element) that contains an I/O configuration definition built by the input/output configuration program (IOCP).

input/output configuration program (IOCP). A S/390 program that defines to a system the channels, I/O devices, paths to the I/O devices, and the addresses of the I/O devices.The output is normally written to a S/390 IOCDS.

interface. (1) A shared boundary between two functional units, defined by functional characteristics, signal characteristics, or other characteristics as appropriate. The concept includes the specification of the connection of two devices having different functions. (2) Hardware, software, or both, that links systems, programs, or devices.

IOCDS. See Input/Output configuration data set.

IOCP. See Input/Output configuration control program.

IODF. The data set that contains the S/390 I/O configuration definition file produced during the defining of the S/390 I/O configuration by HCD. Used as a source for IPL, IOCP and Dynamic I/O Reconfiguration.

IPL. See initial program load.

jumper cable. In an ESCON and FICON environment, an optical cable having two conductors that provides physical attachment between a channel and a distribution panel or an ESCON Director port or a control unit/devices, or between an ESCON Director port and a distribution panel or a control unit/device, or between a control unit/device and a distribution panel. Contrast with trunk cable.

LAN. See local area network.

laser. A device that produces optical radiation using a population inversion to provide light amplification by stimulated emission of radiation and (generally) an optical resonant cavity to provide positive feedback. Laser radiation can be highly coherent temporally, or spatially, or both.

LC connector. An optical fibre cable duplex connector that terminates both jumper cable fibres into one hous- ing and provides physical keying for attachment to an LC duplex receptacle. For technical details, see the NCITS - American National Standard for Information Technology - Fibre Channel Standards document FC-PI.

LCSS. See Logical Channel Subsystem.

LCU. See Logical Control Unit.

LED. See light emitting diode.

licensed internal code (LIC). Microcode that IBM does not sell as part of a machine, but instead, licenses it to the customer. LIC is implemented in a part of storage that is not addressable by user programs. Some IBM products use it to implement functions as an alternate to hard-wire circuitry.

light-emitting diode (LED). A semiconductor chip that gives off visible or infrared light when activated. Contrast Laser.

link address. On an ESCON or a FICPON interface, the portion of a source or destination address in a frame that ESCON or FICON uses to route a frame through an ESCON or FICON director. ESCON and FICON associates the link address with a specific switch port that is on the ESCON or FICON director. Note: For ESCON, there is a one-byte link address. For FICON, there can be a one-byte or two-byte link address specified. One-byte link address for a FICON non-cascade topology and two-byte link address supports a FICON cascade switch topology.

See also port address.

link. (1) In an ESCON or FICON environment, the physical connection and transmission medium used between an optical transmitter and an optical receiver. A link consists of two conductors, one used for sending and the other for receiving, thereby providing a duplex communication path. (2) In an ESCON or FICON I/O interface, the physical connection and transmission medium used between a channel and a control unit, a channel and an ESCON or FICON Director, a control unit and an ESCON or FICON Director, or, at times, between two ESCON Directors or two FICON Directors.

256IBM eServer zSeries 990 Technical Guide

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IBM 990 manual IPL. See initial program load
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990 specifications

The IBM 990 series, often referred to in the context of IBM's pioneering efforts in the realm of mainframe computing, represents a unique chapter in the history of information technology. Introduced in the late 1960s, the IBM 990 series was designed as a powerful tool for enterprise-level data processing and scientific calculations, showcasing the company's commitment to advancing computing capabilities.

One of the main features of the IBM 990 was its architecture, which was built to support a wide range of applications, from business processing to complex scientific computations. The system employed a 32-bit word length, which was advanced for its time, allowing for more flexible and efficient data handling. CPUs in the IBM 990 series supported multiple instructions per cycle, which contributed significantly to the overall efficiency and processing power of the machines.

The technology behind the IBM 990 was also notable for its use of solid-state technology. This provided a shift away from vacuum tube systems that were prevalent in earlier computing systems, enhancing the reliability and longevity of the hardware. The IBM 990 series utilized core memory, which was faster and more reliable than the magnetic drum memory systems that had been standard up to that point.

Another defining characteristic of the IBM 990 was its extensibility. Organizations could configure the machine to suit their specific needs by adding memory, storage, and peripheral devices as required. This modular approach facilitated the growth of systems alongside the technological and operational demands of the business environments they served.

In terms of software, the IBM 990 series was compatible with a variety of operating systems and programming environments, including FORTRAN and COBOL, enabling users to access a broader array of applications. This versatility was a significant advantage, making the IBM 990 an appealing choice for educational institutions, research facilities, and enterprises alike.

Moreover, the IBM 990 was engineered to support multiprocessing, which allowed multiple processes to run simultaneously, further increasing its effectiveness in tackling complex computing tasks.

In summary, the IBM 990 series represents a significant advancement in computing technology during the late 20th century. With a robust architecture, versatile configuration options, and a focus on solid-state technology, the IBM 990 facilitated substantial improvements in data processing capabilities, making it a cornerstone for many businesses and academic institutions of its time. Its impact can still be seen today in the continued evolution of mainframe computing.
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