Multiple Virtual Storage, more commonly called MVS, is the most commonly used operating system on the System/370, System/390 and IBM Z IBM mainframe computers. IBM developed MVS, along with OS/VS1 and SVS, as a successor to OS/360. It is unrelated to IBM's other mainframe operating system lines, e.g., VSE, VM, TPF.
Small Computer System Interface is a set of standards for physically connecting and transferring data between computers and peripheral devices, best known for its use with storage devices such as hard disk drives. SCSI was introduced in the 1980s and has seen widespread use on servers and high-end workstations, with new SCSI standards being published as recently as SAS-4 in 2017.
The IBM System/360 (S/360) is a family of mainframe computer systems that was announced by IBM on April 7, 1964, and delivered between 1965 and 1978. It was the first family of computers designed to cover both commercial and scientific applications and a complete range of applications from small to large. The design distinguished between architecture and implementation, allowing IBM to release a suite of compatible designs at different prices. All but the only partially compatible Model 44 and the most expensive systems use microcode to implement the instruction set, featuring 8-bit byte addressing and fixed point binary, fixed point decimal and hexadecimal floating-point calculations.
A direct-access storage device (DASD) is a secondary storage device in which "each physical record has a discrete location and a unique address". The term was coined by IBM to describe devices that allowed random access to data, the main examples being drum memory and hard disk drives. Later, optical disc drives and flash memory units are also classified as DASD.
The IBM System/370 (S/370) is a range of IBM mainframe computers announced as the successors to the System/360 family on June 30, 1970. The series mostly maintains backward compatibility with the S/360, allowing an easy migration path for customers; this, plus improved performance, were the dominant themes of the product announcement.
Fibre Channel (FC) is a high-speed data transfer protocol providing in-order, lossless delivery of raw block data. Fibre Channel is primarily used to connect computer data storage to servers in storage area networks (SAN) in commercial data centers.
VM is a family of IBM virtual machine operating systems used on IBM mainframes System/370, System/390, zSeries, System z and compatible systems, including the Hercules emulator for personal computers.
In computer hardware, a host controller, host adapter, or host bus adapter (HBA), connects a computer system bus, which acts as the host system, to other network and storage devices. The terms are primarily used to refer to devices for connecting SCSI, SAS, NVMe, Fibre Channel and SATA devices. Devices for connecting to FireWire, USB and other devices may also be called host controllers or host adapters.
The Symmetrix system was an EMC's enterprise storage array. It combined dozens of hard drives into a single virtual device that was then directly attached to a computer or I/O channel, or shared on a storage area network or a local area network. It was the flagship product of EMC in the 1990s and 2000s.
IBM manufactured magnetic disk storage devices from 1956 to 2003, when it sold its hard disk drive business to Hitachi. Both the hard disk drive (HDD) and floppy disk drive (FDD) were invented by IBM and as such IBM's employees were responsible for many of the innovations in these products and their technologies. The basic mechanical arrangement of hard disk drives has not changed since the IBM 1301. Disk drive performance and characteristics are measured by the same standards now as they were in the 1950s. Few products in history have enjoyed such spectacular declines in cost and physical size along with equally dramatic improvements in capacity and performance.
FICON is the IBM proprietary name for the ANSI FC-SB-3 Single-Byte Command Code Sets-3 Mapping Protocol for Fibre Channel (FC) protocol. It is a FC layer 4 protocol used to map both IBM's antecedent channel-to-control-unit cabling infrastructure and protocol onto standard FC services and infrastructure. The topology is fabric utilizing FC switches or directors. Valid rates include 1, 2, 4, 8, 16, and 32 Gigabit per second data rates at distances up to 100 km.
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.
Since the rise of the personal computer in the 1980s, IBM and other vendors have created PC-based IBM-compatible mainframes which are compatible with the larger IBM mainframe computers. For a period of time PC-based mainframe-compatible systems had a lower price and did not require as much electricity or floor space. However, they sacrificed performance and were not as dependable as mainframe-class hardware. These products have been popular with mainframe developers, in education and training settings, for very small companies with non-critical processing, and in certain disaster relief roles.
Count key data (CKD) is a direct-access storage device (DASD) data recording format introduced in 1964, by IBM with its IBM System/360 and still being emulated on IBM mainframes. It is a self-defining format with each data record represented by a Count Area that identifies the record and provides the number of bytes in an optional Key Area and an optional Data Area. This is in contrast to devices using fixed sector size or a separate format track.
This glossary of computer hardware terms is a list of definitions of terms and concepts related to computer hardware, i.e. the physical and structural components of computers, architectural issues, and peripheral devices.
The IBM 9370 systems are "baby mainframe" midrange computers, released 1986 at the very low end of, and compatible with System/370. The media of the day, referring to the VAX systems manufactured by Digital Equipment Corporation (DEC), carried IBM's alleged "VAX Killer" phrase, albeit often skeptically.
Beginning with its 1964 System/360 announcement, IBM's mainframes initially accessed count key data (CKD) subsystems via a channel connected to separate Storage Control Units (SCUs) with attached Direct Access Storage Devices (DASD), typically a hard disk drive. This practice continued in IBM's larger mainframes thru IBM Z; however low end systems generally used lower cost integrated attachments where the function of the SCU was combined with that of the channel, typically called an Integrated File Adapter.
The IBM System/390 is a discontinued mainframe product family implementing ESA/390, the fifth generation of the System/360 instruction set architecture. The first computers to use the ESA/390 were the Enterprise System/9000 (ES/9000) family, which were introduced in 1990. These were followed by the 9672, Multiprise, and Integrated Server families of System/390 in 1994–1999, using CMOS microprocessors. The ESA/390 succeeded ESA/370, used in the Enhanced 3090 and 4381 "E" models, and the System/370 architecture last used in the IBM 9370 low-end mainframe. ESA/390 was succeeded by the 64-bit z/Architecture in 2000.
Bus and Tag is an "IBM standard for a computer peripheral interface", and was commonly used to connect their mainframe computers to peripheral devices such as line printers, disk storage, magnetic tape drives and IBM 3270 display controllers. The technology uses two sets of thick, multi-connector copper cables, one set, carrying data, called the bus, and the other set, carrying control information, called the tag.
