Vax

Information about Vax

DEC VAX

Manufacturer:	Digital Equipment Corporation
Byte size:	8 bits (octet)
Address bus size:	32 bits
Peripheral bus:	Unibus, Massbus, Q-Bus, XMI, VAXBI
Architecture:	CISC, virtual memory
Operating systems:	VAX/VMS, Ultrix, BSD UNIX

This article is about the computing term VAX, not to be confused with the vacuum cleaner/floorcare manufacturer Vax (vacuum).

VAX is a 32-bit computing architecture that supports an orthogonal instruction set (machine language) and virtual addressing (i.e. demand paged virtual memory). It was developed in the mid-1970s by Digital Equipment Corporation (DEC). DEC was later purchased by Compaq, which in turn was purchased by Hewlett-Packard.

The VAX has been perceived as the quintessential CISC processing architecture, with its very large number of addressing modes and machine instructions, including instructions for such complex operations as queue insertion/deletion and polynomial evaluation.

Name

"VAX" was originally an acronym for Virtual Address eXtension, both because the VAX was seen as a 32-bit extension of the older 16-bit PDP-11 and because it was (after Prime Computer) an early adopter of virtual memory to manage this larger address space. Early versions of the VAX processor implemented a "compatibility mode" that emulated many of the PDP-11's instructions, and were in fact called VAX-11 to highlight this compatibility and the fact that VAX-11 was an outgrowth of the PDP-11 family. Later versions offloaded the compatibility mode and some of the less used CISC instructions to emulation in the operating system software. The plural form of VAX is usually VAXes, but VAXen is also heard.

Operating systems

The "native" VAX operating system is DEC's VAX/VMS (renamed to OpenVMS in 1991 or 1992 when it was ported to DEC Alpha, "branded" by the X/Open consortium, and modified to comply with POSIX standards^[1]). The VAX architecture and VMS operating system were "engineered concurrently" to take maximum advantage of each other, as was the initial implementation of the VAXcluster facility. Other VAX operating systems have included various releases of BSD UNIX up to 4.3BSD, Ultrix-32 and VAXeln. More recently, NetBSD and OpenBSD support various VAX models and some work has been done on porting Linux to the VAX architecture.

VAX-11/780

History

The first VAX model sold was the VAX-11/780, which was introduced on October 25, 1977 at the Digital Equipment Corporation's Annual Meeting of Shareholders[1]. The architect of this model was Bill Strecker. Many different models with different prices, performance levels, and capacities were subsequently created. VAX superminis were very popular in the early 1980s.

For a while the VAX-11/780 was used as a baseline in CPU benchmarks because its speed was about one MIPS. Ironically enough, though, the actual number of instructions executed in 1 second was about 500,000. One VAX MIPS was the speed of a VAX-11/780; a computer performing at 27 VAX MIPS would run the same program roughly 27 times as fast as the VAX-11/780. Within the Digital community the term VUP (VAX Unit of Performance) was the more common term, because MIPS do not compare well across different architectures. The related term cluster VUPs was informally used to describe the aggregate performance of a VAXcluster. The performance of the VAX-11/780 still serves as the baseline metric in the BRL-CAD Benchmark, a performance analysis suite included in the BRL-CAD solid modeling software distribution.

VAX 8350 front view with cover removed.

The VAX went through many different implementations. The original VAX was implemented in TTL and filled more than one rack for a single CPU. CPU implementations that consisted of multiple ECL gate array or macrocell array chips included the 8600, 8800 superminis and finally the 9000 mainframe class machines. CPU implementations that consisted of multiple MOSFET custom chips included the 8100 and 8200 class machines.

The MicroVAX I represented a major transition within the VAX family. At the time of its design, it was not yet possible to implement the full VAX architecture as a single VLSI chip (or even a few VLSI chips as was later done with the V-11 CPU of the VAX 8200/8300). Instead, the MicroVAX I was the first VAX implementation to move most of the complexity of the VAX instruction set into emulation software, preserving just the core instructions in hardware. This new partitioning substantially reduced the amount of microcode required and was referred to as the "MicroVAX" architecture. In the MicroVAX I, the ALU and registers were implemented as a single gate-array chip while the rest of the machine control was conventional logic.

A full VLSI (microprocessor) implementation of the MicroVAX architecture then arrived with the MicroVAX II's 78032 CPU and 78132 FPU. This was followed by the V-11, CVAX, SOC ("System On Chip", a single-chip CVAX), Rigel, Mariah and NVAX implementations. The VAX microprocessors extended the architecture to inexpensive workstations and later also supplanted the high-end VAX models. This wide range of platforms (mainframe to workstation) using one architecture was unique in the computer industry at that time.

The VAX architecture was eventually superseded by RISC technology. In 1989 DEC introduced a range of workstations based on processors from MIPS Technologies and running Ultrix. In 1992 DEC introduced their own RISC processor, the Alpha (originally named Alpha AXP), a high performance 64-bit architecture capable of running OpenVMS.

In August 2000, Compaq announced that the remaining VAX models would be discontinued by the end of the year[2]. By 2005 all manufacturing of VAX computers had ceased, but old systems remain in widespread use.

The SRI CHARON-VAX and SIMH software-based VAX emulators remain available.

Processor architecture

Virtual Memory Map

The VAX virtual memory is divided into four sections, each of which is one gigabyte in size:

Section	Address Range
P0	`0x00000000` - `0x3fffffff`
P1	`0x40000000` - `0x7fffffff`
S0	`0x80000000` - `0xbfffffff`
S1	`0xc0000000` - `0xffffffff`

For VMS, P0 was used for user process space, P1 for process stack, S0 for the operating system, and S1 was reserved.

Privilege Modes

The VAX has four privilege modes:

No.	Mode	VMS Usage	Notes
0	Kernel	OS Kernel	Highest Privilege Level
1	Executive	File System
2	Supervisor	Shell (DCL)
3	User	Normal Programs	Lowest Privilege Level

Processor Status Register

CM	TP	MBZ	FD	IS	cmod	pmod	MBZ	IPL	MBZ	DV	FU	IV	T	N	Z	V	C \|31 \|30 \|29 \|27 \|26 \|25 \|23 \|21 \|20 \|15 \|7 \|6 \|5 \|4 \|3 \|2 \|1 \|0

Bits	Meaning
31	PDP-11 compatibility mode
30	trace pending
29:28	MBZ (must be zero)
27	first part done (interrupted instruction)
26	interrupt stack
25:24	current privilege mode
23:22	previous privilege mode
21	MBZ (must be zero)
20:16	IPL (interrupt priority level)
15:8	MBZ (must be zero)
7	decimal overflow trap enable
6	floating-point underflow trap enable
5	integer overflow trap enable
4	trace
3	negative
2	zero
1	overflow
0	carry

Trivia

The phrase, "CVAX — when you care enough to steal the very best" ("СВАКС... Когда вы забатите довольно воровать настоящий лучший"), a play on the well-known Hallmark Cards sloganhttp://pressroom.hallmark.com/hmk_slogan_logo.html) was written in poor Russian on the CVAX microprocessor die http://micro.magnet.fsu.edu/creatures/pages/russians.html. It was intended to send a special message to Soviet engineers attempting to reverse engineer DEC's chip design. http://simh.trailing-edge.com/semi/cvax.html
VAX systems are used in many of the Wm Morrison Supermarkets stores in the UK to control pricing and offers and maintain the tills. Most stores have 2/3 terminals controlled by a MicroVAX. Many new-build stores now use VAX emulators running on a Dell server PC.
VAX systems were the "gold standard" computer platforms for many Computer Science and Computer Engineering programs during the 1980s due to their widespread use at the university-level and their ability to handle dozens, if not hundreds of users at once.

VAX models

Listed in roughly chronological order. The codenames used during development within Digital Equipment Corporation are shown in italic. VAX systems can be broadly classified into those with non-VLSI processors and those with VLSI processors with the MicroVAX-I being a transitional design:

Non-VLSI VAXen

VAX 11/780: Star, TTL CPU, October 1977^[2]

VAX 11/750: Comet, More-compact, lower-performance TTL gate array-based implementation, October 1980

VAX 11/751: ruggedized rack-mount 11/750

VAX 11/730: Nebula, Still-more-compact, still-lower-performance bit slice implementation, April 1982

VAX 11/782: Atlas, Dual-processor 11/780

VAX 11/784: VAXimus, Four 11/780 CPUs sharing a single MA780 memory unit. Very rare

VAX 11/785: Superstar, Faster 11/780, April 1984

VAX 11/787: dual processor 11/785

VAX 11/788: VISQ

VAX 11/725: LCN, Low-Cost Nebula

VAX 8600: Venus, aka 11/790 during development, ECL gate array CPU, October 1984

VAX 8650: Morningstar, aka 11/795 during development, a faster 8600, last model to use SBI backplane also used by VAX 11/78x models, last model to have PDP-11 compatibility mode. All subsequent 8000 series models use VAXBI instead of SBI

VAX 8x00: Gemini, Fall-back in case the LSI-based Scorpio failed (never shipped)

VAX 8500: Flounder, Single-processor, deliberately-slowed VAX 8700

VAX 8530: Skipjack, Single-processor, less-slowed VAX 8700

VAX 8550: Skipjack, Single-processor 8800, unexpandable

VAX 8700: Nautilus, Single-processor Nautilus, expandable to full 8800

VAX 8800: Nautilus, Dual-processor ECL Macrocell array-based implementation, January 1986. Later also known as VAX 8820N

VAX 8810/8820/8830/8840: Polarstar, a Nautilus variant with one to four processors and an updated console processor

VAX 8974/8978: cluster comprising four or eight VAX 8810s respectively, January 1987

VAX 9000: Aridus, Air-cooled. Originally designed to be water-cooled, named Aquarius, ECL macrocell array CPU, VAXBI, October 1989^[3] ;VAX 9000 Model 110 ;VAX 9000 Model 210 ;VAX 9000 Model 310 ;VAX 9000 Model 4x0: x = number of processors, 1–4

A transitional VAX

MicroVAX/VAXstation I: Seahorse, KD32 CPU, October 1984

VLSI VAXen

MicroVAX series: some models also sold as VAXservers

;MicroVAX II: Mayflower, KA630 CPU, May 1985

:;Industrial VAX 630: MicroVAX II in BA213 enclosure

;MicroVAX III: BA23- or BA123-enclosure MicroVAX upgraded with KA650 CVAX CPU

;MicroVAX III+: BA23- or BA123-enclosure MicroVAX upgraded with KA655 CPU

;VAX 4: BA23- or BA123-enclosure MicroVAX upgraded with KA660 CPU

;MicroVAX 2000: TeamMate, desktop form factor, February 1987

;MicroVAX 3100 series: desktop form-factor, 1987 onwards

:;MicroVAX 3100 Model 10: TeamMate II, KA41-A CVAX processor

:;MicroVAX 3100 Model 10e: TeamMate II, KA41-D CVAX+ processor

:;MicroVAX 3100 Model 20: Model 10 in larger enclosure

:;MicroVAX 3100 Model 20e: Model 20 in larger enclosure

:;MicroVAX 3100 Model 30: Waverley/S, KA45 SOC CPU

:;MicroVAX 3100 Model 40: Model 30 in larger enclosure

:;MicroVAX 3100 Model 80: Waverley/M, KA47 Mariah CPU

:;MicroVAX 3100 Model 85: Waverley/M+, KA55 NVAX CPU

:;MicroVAX 3100 Model 88: Waverley/M+, KA58 NVAX CPU

:;MicroVAX 3100 Model 90: Cheetah, KA50 NVAX CPU

:;MicroVAX 3100 Model 95: Cheetah+, KA51 NVAX CPU

:;MicroVAX 3100 Model 96: Cheetah++, KA56 NVAX CPU

:;MicroVAX 3100 Model 98: Cheetah++, KA59 NVAX CPU

;MicroVAX 3300/3400: Mayfair, used KA640 CPU card

;MicroVAX 3500/3600: Mayfair-II, used KA650 CPU card, September 1987

;MicroVAX 3800/3900: Mayfair-III, used KA655 CPU card

VAXstation series

;VAXstation II: MicroVAX II workstation configuration

;VAXstation II/GPX: Caylith, hardware-enhanced, high-performance color graphics, December 1985

;VAXstation 2000: VAXstar MicroVAX 2000 workstation configuration

;VAXstation 3100 series

:;VAXstation 3100 Model 30: PVAX, KA42-A CVAX CPU

:;VAXstation 3100 Model 38: PVAX rev#7, KA42-B CVAX CPU

:;VAXstation 3100 Model 40: Model 30 in larger enclosure

:;VAXstation 3100 Model 48: Model 38 in larger enclosure

:;VAXstation 3100 Model 76: RigelMAX, KA43-A Rigel CPU

:;VT1300: X terminal (essentially a diskless VAXstation 3100 Model 30)

;VAXstation 3200/3500: Mayfair/GPX, KA650 CVAX CPU

;VAXstation 3520/3540: Firefox, two or four KA60 CVAX processors

;VAXstation 4000: TURBOchannel bus

:;VAXstation 4000/VLC aka Model 30: PVAX2/VLC, KA48 SOC ("System On Chip") CPU, slim pizza box, accepting standard 72-pin parity SIMM modules

:;VAXstation 4000 Model 60: PMariah, KA46 Mariah CPU

:;VAXstation 4000 Model 90: Cougar, KA49-A NVAX CPU

:;VAXstation 4000 Model 90A: Cougar+, KA49-A NVAX CPU

:;VAXstation 4000 Model 96: Cougar++, KA49-C NVAX CPU

;VAXstation 8000: Lynx, very rare high-end 3D workstation based on VAX 8200

VAX 4000 series: MicroVAX name dropped ;VAX 4000 Model 50: VAXbrick, KA600 NVAX processor, CPU upgrade for MicroVAX 3x00 or VAX 4000-200 ;VAX 4000 Model 100/100A: Cheetah-Q, KA52 NVAX processor ;VAX 4000 Model 105A: Cheetah-Q+, faster KA53 NVAX processor ;VAX 4000 Model 106A/108: Cheetah-Q++, faster KA54/KA57 NVAX processor ;VAX 4000 Model 200: Spitfire, KA660 SOC processor ;VAX 4000 Model 300: Pele, KA670 Rigel 1.5 µm CMOS processor chipset,^[4] mid-1989 ;VAX 4000 Model 400: Omega, KA675 NVAX processor ;VAX 4000 Model 500/500A: Omega/N, KA680/KA681 NVAX processor ;VAX 4000 Model 505A/600/600A: Omega/N+, KA690/KA691 NVAX processor ;VAX 4000 Model 700A: Legacy, KA692 NVAX processor ;VAX 4000 Model 705A: Legacy+, KA694 NVAX processor

KA820-AA CPU for 8250/8350

VAX 8200/8300: Scorpio, one or two V-11 CPUs respectively, VAXBI backplane, January 1986 ;VAX 8250/8350: Faster Scorpios

VAX 6000 series

x = number of processors, max 6 for the 600 series

;VAX 6000 Model 2x0 aka VAX 62x0 series: Calypso,: used CVAX chipset, April 1988

;VAX 6000 Model 3x0 aka VAX 63x0 series: Hyperion, CVAX+ 1.5 µm CMOS processor chipset, January 1989

;VAX 6000 Model 4x0 aka VAX 64x0 series: Calypso/XRP, Rigel 1.5 µm CMOS chipset, mid-1989

;VAX 6000 Model 5x0 aka VAX 65x0 series: Calypso/XMP, Mariah 1.0 µm CMOS chipset, October 1990

;VAX 6000 Model 6x0 aka VAX 66x0 series: Neptune, NVAX 0.75 µm CMOS chipset, November 1991

;VAX 6333: prepackaged cluster of VAX 6000 Model 300 series

VAX 7000 series:

;VAX 7000 Model 6x0: Laser/Neon, Up to six NVAX+ processors, field-upgradable to Alpha AXP 64-bit processor(s) (ie. DEC 7000 AXP configuration), July 1992

;VAX 7000 Model 7x0: Laser/Krypton, NVAX5 processor(s)

;VAX 7000 Model 8x0: Laser/Krypton+, faster NVAX5 processor(s)

VAX 10000 Model 6x0: Blazer, similar to VAX 7000 Model 6x0

VAXft fault-tolerant series:

;VAXft 3000 Model 310: Cirrus, CVAX+ CPUs, two-processor, fault tolerant system, February 1990

;VAXft Model 110: slower, lower cost Cirrus

;VAXft Model 410/610/612: Cirrus II, SOC CPUs

;VAXft Model 810: Jetstream, NVAX+ CPUs

Miscellaneous

VAXstation 100 (VS100): Graphics terminal based on a MC68000 microprocessor, intended to connect to a VAX system via Unibus, May 1983.^[5]

VAXstation 500: Color successor to VAXstation 100, October 1985.^[6]

VAX XXXX: BVAX, High-end VAX (never shipped)

Clones

A number of clones of VAX models, both authorized and unauthorized, were produced. Examples include:

Systime Ltd. of the United Kingdom produced clones of early VAX models such as the Systime 8750 (equivalent to the VAX 11/750).^[7]
Norden Systems produced the ruggedized, military-specification MIL VAX series.^[1]
The Hungarian Central Research Institute for Physics (KFKI) produced a series of clones of early VAX models, the TPA-11/540, 560 and 580.^[8]

References

1. ^ Rainville, Jim & Karen Howard, eds. (1997), VAX/VMS at 20, Digital Equipment Corporation, <[3] (retrieved on 2007-10-13)
2. ^ VAX timeline, Hewlett Packard website
3. ^ DIGITAL Computing Timeline
4. ^ Trailing edge, The Computer History Simulation Project
5. ^ Henry M. Levy (January 1984). "VAXstation: A General-Purpose Raster Graphics Architecture". ACM Transactions on Graphics (TOG) 3.
6. ^ Bell, Gordon (1986). "Toward a History of (Personal) Workstations". Proc ACM Conference on the History of Personal Workstations: 1-17, ACM. Retrieved on 2007-10-13.
7. ^ RAL Informatics Report 1984-85. Retrieved on 2007-10-15.
8. ^ The TPA story. Retrieved on 2007-10-15.

Digital Equipment Corporation was a pioneering American company in the computer industry. It is often referred to within the computing industry as DEC. (This acronym was frequently officially used by Digital itself,^[1] but the official name was always DIGITAL.
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BIT is an acronym for:

Bannari amman Institute of Technology
Bangalore Institute of Technology
Beijing Institute of Technology
Benzisothiazolinone
Bilateral Investment Treaty
Bhilai Institute of Technology - Durg

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In computing, an octet is a grouping of eight bits.

In France, French Canada and Romania, the word octet usually means byte; a megabyte (MB) is called a megaoctet in France, Romania and also French Canada. Bit and Byte are homophones in the French language.
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In computer architecture, 32-bit integers, memory addresses, or other data units are those that are at most 32 bits (4 octets) wide. Also, 32-bit CPU and ALU architectures are those that are based on registers, address buses, or data buses of that size.
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The Unibus was the earliest of several bus technologies used with PDP-11 and early VAX systems manufactured by the Digital Equipment Corporation of Maynard, Massachusetts.

The Unibus was composed of 72 wires (2 connectors x 36 lines per connector).
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The Massbus was a high-performance computer input/output bus designed in the 1970s by the Digital Equipment Corporation of Maynard, Massachusetts.

The bus was used by Digital to interconnect its highest-performance computers with magnetic disk and magnetic tape storage
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The Q-bus (also known as the LSI-11 Bus) was one of several bus technologies used with PDP and MicroVAX computer systems manufactured by the Digital Equipment Corporation of Maynard, Massachusetts.
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complex instruction set computer (CISC pronouced sisk) is a microprocessor instruction set architecture (ISA) in which each instruction can execute several low-level operations, such as a load from memory, an arithmetic operation, and a memory store, all in a single
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This article is about the computer term. For the TBN game show, see Virtual Memory (game show).

Virtual memory is an abstraction implemented in a computer that gives an application program the impression it has contiguous working memory, while in fact it is
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OpenVMS^[1] (Open Virtual Memory System or just VMS) is the name of a high-end computer server operating system that runs on the VAX^[2] and Alpha^[3]
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Ultrix (officially all-caps ULTRIX) was the brand name of Digital Equipment Corporation's (DEC) native Unix systems. While ultrix is the Latin word for avenger, the name was chosen solely for its sound.
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Berkeley Software Distribution (BSD, sometimes called Berkeley Unix) is the UNIX derivative distributed by the University of California, Berkeley, starting in the 1970s.
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For the VAX computer, see VAX.

Vax is a brand of vacuum and carpet cleaning products. It is part of Hong Kong based TechTronic Industries Co. Ltd , with a 2005 turnover of $HK22B.

History

Vax was started by Alan Brazier in the 1970s.
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computer architecture is the conceptual design and fundamental operational structure of a computer system. It is a blueprint and functional description of requirements (especially speeds and interconnections) and design implementations for the various parts of a computer —
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Orthogonal instruction set is a term used in computer engineering. A computer's instruction set is said to be orthogonal if any instruction can use data of any type via any addressing mode.
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Machine code or machine language is a system of instructions and data directly executed by a computer's central processing unit. Machine code is the lowest-level of abstraction for representing a computer program.
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paging, sometimes called swapping, is a transfer of pages between main memory and an auxiliary store, such as hard disk drive.^[1] Paging is an important part of virtual memory implemention in most contemporary general-purpose operating systems, allowing to easily
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This article is about the computer term. For the TBN game show, see Virtual Memory (game show).

Compaq Computer Corporation was an American personal computer company founded in 1982, and is now a brand name of Hewlett-Packard.

The company was formed by Rod Canion, Jim Harris and Bill Murto — former Texas Instruments senior managers.
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Hewlett-Packard Co.

Public (NYSE: HPQ )
Founded Palo Alto, California (1939)
Headquarters Palo Alto, California, USA

Key people Bill Hewlett, Co-founder
David Packard, Co-founder
Mark V.
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Addressing modes, a concept from computer science, are an aspect of the instruction set architecture in most central processing unit (CPU) designs. The various addressing modes that are defined in a given instruction set architecture define how machine language instructions in that
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queue (pronounced /kjuː/) is a particular kind of collection in which the entities in the collection are kept in order and the principal (or only) operations on the collection are the addition of entities to the rear terminal position and removal of entities from the front
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In mathematics, a polynomial is an expression that is constructed from one or more variables and constants, using only the operations of addition, subtraction, multiplication, and constant positive whole number exponents. is a polynomial.
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Acronyms and initialisms are abbreviations, such as NATO, laser, and IBM, that are formed using the initial letters of words or word parts in a phrase or name.
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16-bit integers, memory addresses, or other data units are those that are at most 16 bits (2 octets) wide. Also, 16-bit CPU and ALU architectures are those that are based on registers, address buses, or data buses of that size.
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The PDP-11 was a series of 16-bit minicomputers sold by Digital Equipment Corp. in the 1970s and 1980s. The PDP-11 was a successor to DEC's PDP-8 computer in the PDP series of computers. It had several uniquely innovative features, and was easier to program than its predecessors.
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Prime Computer was a Natick, Massachusetts-based producer of minicomputers from 1972 until 1992.

Founders

The company was started by 7 founders, some of whom worked on the Multics project at MIT.
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Vax

Information about Vax

Name

Operating systems

History

Processor architecture

Virtual Memory Map

Privilege Modes

Processor Status Register

Trivia

VAX models

Non-VLSI VAXen

A transitional VAX

VLSI VAXen

Miscellaneous

Clones

References

External links

History

Founders