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

ESA/390. See Enterprise Systems Architecture/390.

ESCD console. The ESCON Director display and keyboard device used to perform operator and service tasks at the ESCD.

ESCD. Enterprise Systems Connection (ESCON) Director.

ESCON channel. A channel having an Enterprise Systems Connection channel-to-control-unit I/O interface that uses optical cables as a transmission medium. May operate in CBY, CNC, CTC or CVC mode. Contrast with parallel channel.

ESCON Director. An I/O interface switch that provides the interconnection capability of multiple ESCON interfaces (or FICON FCV (9032-5) in a distributed-star topology.

ESCON Multiple Image Facility (EMIF). In the ESA/390 architecture, a function that allows LPARs to share an ESCON channel path (and other channel types) by providing each LPAR with its own channel-subsystem image.

ESCON. See Enterprise System Connection.

FCS. See fibre channel standard.

FCTC. FICON Channel-to-Channel

fiber optic cable. See optical cable.

fiber optics. The branch of optical technology concerned with the transmission of radiant power through fibers made of transparent materials such as glass, fused silica, and plastic.

Note: Telecommunication applications of fiber optics use optical fibers. Either a single discrete fiber or a non-spatially aligned fiber bundle can be used for each information channel. Such fibers are often called optical fibers to differentiate them from fibers used in non-communication applications.

fiber. See optical fiber.

fibre channel standard. An ANSI standard for a computer peripheral interface. The I/O interface defines a protocol for communication over a serial interface that configures attached units to a communication fabric. The protocol has four layers. The lower of the four layers defines the physical media and interface, the upper of the four layers defines one or more logical protocols (for example, FCP for SCSI command protocols and FC-SB-2 for FICON for ESA/390). Refer to ANSI X3.230.1999x.

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FICON channel. A channel having a fibre-channel channel-to-control-unit I/O interface that uses optical cables as a transmission medium. The FICON channel may operate in(1) FC mode (FICON native mode - FC-SB-2/3), (2) FCV mode (FICON conversion mode to

aIBM 9032-5), (3) FCP mode (FICON channel operating in “open mode”, which is FC-FCP).

FICON. (1) An ESA/390 and z/Architecture computer peripheral interface. The I/O interface uses ESA/390 and z/Architecture logical protocols over a FICON serial interface that configures attached units to a FICON communication fabric. (2) An FC4 adopted standard that defines an effective mechanism for the export of the SBCON command protocol via fibre channels.

field replaceable unit (FRU). An assembly that is replaced in its entirety when any one of its required components fails.

FRU. See field replaceable unit.

Giga bit. Usually used to refer to a data rate, the number of Giga bits being transferred in one second.

Giga byte. Usually used to refer to an amount of storage space or size. One Giga-byte is 109, or 1,073,741,824 bytes.

half duplex. In data communication, pertaining to transmission in only one direction at a time. Contrast with duplex.

hard disk drive. (1) A storage media within a storage server used to maintain information that the storage server requires. (2) A mass storage medium for computers that is typically available as a fixed disk or a removable cartridge.

HDA. Head and disk assembly.

HDD. See hard disk drive.

head and disk assembly. The portion of an HDD associated with the medium and the read/write head.

I/O configuration. The collection of channel paths, control units, and I/O devices that attaches to the processor. This may also include channel switches (for example, an ESCON Director).

I/O. See input/output.

ID. See identifier.

Identifier. A unique name or address that identifies things such as programs, devices or systems.

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IBM 990 manual ESA/390. See Enterprise Systems Architecture/390, Fiber optic cable. See optical cable
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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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