VAXft

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The VAXft was a family of fault-tolerant minicomputers developed and manufactured by Digital Equipment Corporation (DEC) using processors implementing the VAX instruction set architecture (ISA). "VAXft" stood for "Virtual Address Extension, fault tolerant". [1] These systems ran the OpenVMS operating system, and were first supported by VMS 5.4. Two layered software products, VAXft System Services and VMS Volume Shadowing, were required to support the fault-tolerant features of the VAXft and for the redundancy of data stored on hard disk drives.

Digital Equipment Corporation, using the trademark Digital, was a major American company in the computer industry from the 1960s to the 1990s. The company was co-founded by Ken Olsen and Harlan Anderson in 1957. Olsen was president until forced to resign in 1992, after the company had gone into precipitous decline.

VAX Computer architecture, and a range of computers

VAX is a line of computers developed by Digital Equipment Corporation (DEC) in the mid-1970s. The VAX-11/780, introduced on October 25, 1977, was the first of a range of popular and influential computers implementing the VAX instruction set architecture (ISA).

An instruction set architecture (ISA) is an abstract model of a computer. It is also referred to as architecture or computer architecture. A realization of an ISA is called an implementation. An ISA permits multiple implementations that may vary in performance, physical size, and monetary cost ; because the ISA serves as the interface between software and hardware. Software that has been written for an ISA can run on different implementations of the same ISA. This has enabled binary compatibility between different generations of computers to be easily achieved, and the development of computer families. Both of these developments have helped to lower the cost of computers and to increase their applicability. For these reasons, the ISA is one of the most important abstractions in computing today.

Contents

Architecture

All VAXft systems shared the same basic system architecture. A VAXft system consisted of two "zones" that operated in lock-step: "Zone A" and "Zone B". Each zone was a fully functional computer, capable of running an operating system, and was identical to the other in hardware configuration. Lock-step was achieved by hardware on the CPU module. The CPU module of each zone was connected to the other with a crosslink cable. The crosslink cables carried the results of instructions executed by one CPU module to the other, where they were compared by hardware with the results of the same instructions executed by the latter to ensure that they were identical. The two zones were kept synchronous by a clock signal carried by the crosslink cables. When a hardware failure occurred in one of the zones, the affected zone was brought offline without bringing down the other zone, which continued to operate as normal. When repairs were completed, the offline zone was powered on and automatically resynchronized with the other zone, restoring redundancy. [2] [3]

Lockstep systems are fault-tolerant computer systems that run the same set of operations at the same time in parallel. The redundancy (duplication) allows error detection and error correction: the output from lockstep operations can be compared to determine if there has been a fault if there are at least two systems, and the error can be automatically corrected if there are at least three systems, via majority vote. The term "lockstep" originates in the army usage, where it refers to the synchronized walking, in which the marchers walk as closely together as physically practical.

VAXft Model 310

The VAXft Model 310, introduced as the VAXft 3000 Model 310, code named "Cirrus", was introduced in February 1990 and shipped in June. It was the first VAXft model, and was DEC's first fault-tolerant computer that was generally available. At the 1991 launch of new VAXft models, the VAX 3000 Model 310 was renamed to follow the new naming scheme, becoming the VAXft Model 310. The Model 310 had a theoretical maximum performance of 3.8 VUPs. [4]

The VAX Unit of Performance, or VUP for short, is an obsolete measurement of computer performance used by Digital Equipment Corporation (DEC). 1 VUP was equivalent to the performance of a VAX 11/780 completing a given task.

When announced, the Model 310 had a starting price of US$200,000. In August 1990, slow sales prompted DEC to reduce the US price of the Model 310 to US$168,000.

It used the KA520 CPU module containing a 16.67 MHz (60 ns cycle time) CVAX+ chip set with 32 KB of external secondary cache. The system contained two such CPU modules, one in each zone, running in lock-step.

VAXft Model 110

The VAXft Model 110, code named "Cirrus", was an entry-level model announced on 18 March 1991 alongside three other models. The Model 110 was essentially a low-cost model of the VAXft Model 310, and had a theoretical maximum performance of 2.4 VUPs.

It contained two zones packed side by side in an enclosure. Compared to the Model 310, it was limited in expandability in regards to memory, storage capacity and available options. It was available in either a pedestal or rackmount configuration. The rackmount configuration was a pedestal without the plastic covers or casters that fitted in a standard 19-inch RETMA cabinet. [5]

Each zone had a five-slot backplane for a KA510 CPU module, one to three 32 MB MS520 memory modules, one or two KFE52 system I/O controller modules and one or two DEC WANcontroller 620 (DSF32) wide area network (WAN) communications adapters. The leftmost slot was the first slot. The primary system controller resided in the first slot, the CPU module in the second, and the memory modules in the third, fourth and fifth slots. The second system I/O controller resided in either the fourth and fifth slots and the WAN communications adapters also in the fourth and fifth slots. The most basic system contained a CPU module, a memory module and a system I/O controller.

Wide area network Computer network that connects devices across a large distance and area

A wide area network (WAN) is a telecommunications network that extends over a large geographical area for the primary purpose of computer networking. Wide area networks are often established with leased telecommunication circuits.

The DEC WANcontroller 620 was designed for use in VAXft systems. It provided two synchronous lines, each with a bandwidth of 64 KB. The lines could be operated as two independent lines or paired to provide redundancy.

VAXft Model 410

The VAXft Model 410, code named "Cirrus II", was a mid-range model announced on 18 March 1991 alongside three other models. Originally supposed to ship in June or July 1991, it was delayed until September 1991, with the reason given by DEC being that it wanted to tune a new release of VMS for the system. The Model 410 was identical to the Model 310, but used the KA550 CPU module containing a 28.57 MHz (35 ns cycle time) SOC microprocessor with 128 KB of external secondary cache. It supported up to 256 MB of memory. The Model 410 had a theoretical maximum performance of 6.0 VUPs.

VAXft Model 610

The VAXft Model 610, code named "Cirrus II", was a mid-range model announced on 18 March 1991 alongside three other models. Originally supposed to ship in June or July 1991, it was delayed until September 1991, with the reason given by DEC being that it wanted to tune a new release of VMS for the system.

The Model 610 was architecturally identical to the Model 410, except that the two zones were packaged vertically a 60" high cabinet, with Zone A above Zone B. The cabinet had more storage capacity than the systems packaged in pedestals, and for this reason the Model 610 was intended for data centers. It could have one or two expander cabinets placed on the left and right of the system for additional storage devices. These cabinets were front to rear cooled.

VAXft Model 612

The VAXft Model 612 was a high-end model announced on 18 March 1991 alongside three other models. Originally supposed to ship in June or July 1991, it was delayed until September 1991, with the reason given by DEC being that it wanted to tune a new release of VMS for the system. The Model 612 was a VAXcluster of two VAXft Model 610s with an expansion cabinet positioned between the two systems as standard. It had a theoretical maximum performance of 12.0 VUPs. A second expansion cabinet could be added between the two system cabinets.

VAXft Model 810

The VAXft Model 810, code named "Jetstream", was a high-end model introduced in October 1993 instead of the targeted introduction date in the late summer or early fall of 1992. [6] The system was developed by DEC, but was manufactured by an Italian industrial manufacturer, Alenia SpA. It had a theoretical maximum performance of 30.0 VUPs.

The Model 810 was a third generation VAXft system. It contained two zones vertically packaged in a cabinet. An optional expansion cabinet could be connected to the system, in addition to two uninterruptable power supplies, one for each zone. [7]

It used the KA560-AA CPU module, which contained two 83.33 MHz (12 ns cycle time) NVAX+ microprocessors with 512 KB of B-cache (L2 cache). The module's two microprocessors operated a in lock-step fashion, and like previous VAXft systems, there were two such CPU modules in a system, one in each of the two zones, which operated in a lock-step fashion.

The Model 810 cabinet was 60.0 cm (24 in) wide, 170.0 cm (67 in) high and 86.0 cm (34 in) deep.

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VAXstation family of workstation computers

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NVAX microprocessor

The NVAX is a microprocessor developed and fabricated by Digital Equipment Corporation (DEC) that implemented the VAX instruction set architecture (ISA). The NVAX was a high-end single-chip VAX microprocessor. A variant of the NVAX, the NVAX+, differed in the bus interface and external cache supported, but was otherwise identical in regards to microarchitecture. The NVAX is clocked at frequencies of 83.3 MHz, 71 MHz and 62.5 MHz, while the NVAX+ is clocked at a frequency of 90.9 MHz.

VAX-11

The VAX-11 is a discontinued family of minicomputers developed and manufactured by Digital Equipment Corporation (DEC) using processors implementing the VAX instruction set architecture (ISA), succeeding the PDP-11. The VAX-11/780 is the first VAX computer.

MicroVAX family of low-cost minicomputers

The MicroVAX was a family of low-cost minicomputers developed and manufactured by Digital Equipment Corporation (DEC). The first model, the MicroVAX I, was introduced in 1983. They used processors that implemented the VAX instruction set architecture (ISA) and were succeeded by the VAX 4000.

DEC 3000 AXP series of computer workstations and servers

DEC 3000 AXP was the name given to a series of computer workstations and servers, produced from 1992 to around 1995 by Digital Equipment Corporation. The DEC 3000 AXP series formed part of the first generation of computer systems based on the 64-bit Alpha AXP architecture. Supported operating systems for the DEC 3000 AXP series were DEC OSF/1 AXP and OpenVMS AXP.

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The VAX 4000 was a family of low-end minicomputers developed and manufactured by Digital Equipment Corporation (DEC) using microprocessors implementing the VAX instruction set architecture (ISA). The VAX 4000 succeeded the MicroVAX family. It was the last family of low-end VAX systems, as the platform was discontinued by Compaq.

VAX 6000 family of minicomputers

The VAX 6000 was a family of minicomputers developed and manufactured by Digital Equipment Corporation (DEC) using processors implementing the VAX instruction set architecture (ISA). Originally, the VAX 6000 was intended to be a mid-range VAX product line complementing the VAX 8000, but with the introduction of the VAX 6000 Model 400 series, the older VAX 8000 was discontinued in favor of the VAX 6000, which offered slightly higher performance for half the cost.

The VAX 7000 and VAX 10000 were a series of high-end multiprocessor minicomputers developed and manufactured by Digital Equipment Corporation (DEC), introduced in July 1992. These systems used microprocessors implementing the VAX instruction set architecture (ISA). These computers ran Digital's OpenVMS operating system.

VAX 8000

The VAX 8000 is a discontinued family of minicomputers developed and manufactured by Digital Equipment Corporation (DEC) using processors implementing the VAX instruction set architecture (ISA).

The VAXserver was a family of minicomputers developed and manufactured by Digital Equipment Corporation (DEC) using processors implementing the VAX instruction set architecture (ISA). The VAXserver models were variants of various VAX-based computers which were configured to only run operating systems which were licensed for network server use and not interactive time-sharing use. This was accomplished with different CPU modules and firmware.

The Digital Storage Systems Interconnect (DSSI) is a computer bus developed by Digital Equipment Corporation for connecting storage devices and clustering VAX systems. It was designed as a smaller and lower-cost replacement for the earlier DEC Computer Interconnect that would be more suitable for use in office environments. DSSI was superseded by Parallel SCSI.

Rigel (microprocessor)

Rigel was a microprocessor chip set developed and fabricated by Digital Equipment Corporation (DEC) that implemented the VAX instruction set architecture (ISA). It was introduced on 11 July 1989 with the introduction of the VAX 6000 Model 400, the first system to feature the chip set. Rigel was also used in the VAX 4000 Model 300 and VAXstation 3100 Model 76. Production Rigel CPUs were rated at 35 to 43 MHz.

References

  1. South, David W. (1994). The Computer and Information Science and Technology Abbreviations and Acronyms Dictionary . CRC Press. p. 226. ISBN   978-0-8493-2444-4.
  2. Siewiorek, Daniel P.; Swarz, Robert S. (1998). Reliable computer systems design and evaluation. A K Peters, Ltd. pp.  745–767. ISBN   978-1-56881-092-8.
  3. William F. Bruckert, Carlos Alonso and James M. Melvin. "Verification of the First Fault-tolerant VAX System", Digital Technical Journal, Volume 3, Number 1, Winter 1991.
  4. VAX Unit of Performance (VUP) - A measure of performance, one VUP is roughly equivalent to a VAX-11/780's performance.
  5. VAXft Systems Owner's Manual, December 1991. Order number: EK-VXFT1-OM.004. Digital Equipment Corporation.
  6. Stedman, Craig (25 January 1993). "DEC fault-tolerant line in the air". Electronic News .
  7. VAXft Systems Model 810 Operating Information, June 1993. Order Number: EK-VXFTA-OP.A01. Digital Equipment Corporation.