VAX (an acronym for Virtual Address eXtension) is a series of computers featuring a
32-bit
In computer architecture, 32-bit computing refers to computer systems with a processor, memory, and other major system components that operate on data in 32-bit units. Compared to smaller bit widths, 32-bit computers can perform large calculation ...
instruction set architecture
In computer science, an instruction set architecture (ISA), also called computer architecture, is an abstract model of a computer. A device that executes instructions described by that ISA, such as a central processing unit (CPU), is called an ' ...
(ISA) and
virtual memory
In computing, virtual memory, or virtual storage is a memory management technique that provides an "idealized abstraction of the storage resources that are actually available on a given machine" which "creates the illusion to users of a very l ...
that was developed and sold by
Digital Equipment Corporation
Digital Equipment Corporation (DEC ), 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 unt ...
(DEC) in the late 20th century. The
VAX-11/780
The VAX-11 is a discontinued family of 32-bit superminicomputers, running the Virtual Address eXtension (VAX) instruction set architecture (ISA), developed and manufactured by Digital Equipment Corporation (DEC). Development began in 1976. In ad ...
, introduced October 25, 1977, was the first of a range of popular and influential computers implementing the VAX ISA. The VAX family was a huge success for DEC – over 100 models were introduced over the lifetime of the design, with the last members arriving in the early 1990s. The VAX was succeeded by the
DEC Alpha
Alpha (original name Alpha AXP) is a 64-bit reduced instruction set computer (RISC) instruction set architecture (ISA) developed by Digital Equipment Corporation (DEC). Alpha was designed to replace 32-bit VAX complex instruction set computers ...
, which included several features from VAX machines to make
porting
In software engineering, porting is the process of adapting software for the purpose of achieving some form of execution in a computing environment that is different from the one that a given program (meant for such execution) was originally desi ...
from the VAX easier.
VAX was designed as a successor to the
16-bit
16-bit microcomputers are microcomputers that use 16-bit microprocessors.
A 16-bit register can store 216 different values. The range of integer values that can be stored in 16 bits depends on the integer representation used. With the two mos ...
PDP-11
The PDP-11 is a series of 16-bit minicomputers sold by Digital Equipment Corporation (DEC) from 1970 into the 1990s, one of a set of products in the Programmed Data Processor (PDP) series. In total, around 600,000 PDP-11s of all models were sold, ...
, one of the most successful
minicomputer
A minicomputer, or colloquially mini, is a class of smaller general purpose computers that developed in the mid-1960s and sold at a much lower price than mainframe and mid-size computers from IBM and its direct competitors. In a 1970 survey, ...
s in history with approximately 600,000 examples sold. The system was designed to offer
backward compatibility
Backward compatibility (sometimes known as backwards compatibility) is a property of an operating system, product, or technology that allows for interoperability with an older legacy system, or with input designed for such a system, especially i ...
with the PDP-11 while extending the memory to a full
32-bit
In computer architecture, 32-bit computing refers to computer systems with a processor, memory, and other major system components that operate on data in 32-bit units. Compared to smaller bit widths, 32-bit computers can perform large calculation ...
implementation and adding
demand paged virtual memory
In computing, virtual memory, or virtual storage is a memory management technique that provides an "idealized abstraction of the storage resources that are actually available on a given machine" which "creates the illusion to users of a very l ...
. The name VAX refers to its ''Virtual Address eXtension'' concept that allowed programs to make use of this newly available memory while still being compatible with unmodified user mode PDP-11 code. The name "VAX-11", used on early models, was chosen to highlight this capability. The VAX ISA is considered a
complex instruction set computer
A complex instruction set computer (CISC ) is a computer architecture in which single instructions can execute several low-level operations (such as a load from memory, an arithmetic operation, and a memory store) or are capable of multi-step ...
(CISC) design.
Later models in the series dropped the −11 branding as PDP-11 compatibility was no longer a major concern. The line expanded to both high-end machines like the
VAX 9000
The VAX 9000 is a discontinued family of Minicomputers developed and manufactured by Digital Equipment Corporation (DEC) using custom ECL-based processors implementing the VAX instruction set architecture (ISA). Equipped with optional vector proc ...
as well as to the
workstation
A workstation is a special computer designed for technical or scientific applications. Intended primarily to be used by a single user, they are commonly connected to a local area network and run multi-user operating systems. The term ''workstat ...
-scale systems like the
VAXstation
The VAXstation is a discontinued family of workstation computers developed and manufactured by Digital Equipment Corporation using processors implementing the VAX instruction set architecture. VAXstation systems were typically shipped with either ...
series.
The VAX family ultimately contained ten distinct designs and over 100 individual models in total. All of these were compatible with each other and normally ran the
VAX/VMS
OpenVMS, often referred to as just VMS, is a multi-user, multiprocessing and virtual memory-based operating system. It is designed to support time-sharing, batch processing, transaction processing and workstation applications. Customers using Ope ...
operating system
An operating system (OS) is system software that manages computer hardware, software resources, and provides common services for computer programs.
Time-sharing operating systems schedule tasks for efficient use of the system and may also in ...
.
VAX has been perceived as the quintessential CISC ISA, with its very large number of
assembly language
In computer programming, assembly language (or assembler language, or symbolic machine code), often referred to simply as Assembly and commonly abbreviated as ASM or asm, is any low-level programming language with a very strong correspondence be ...
programmer-friendly
addressing mode
Addressing modes 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 the machine language instructions in ...
s and machine instructions, highly
orthogonal instruction set
In computer engineering, an orthogonal instruction set is an instruction set architecture where all instruction types can use all addressing modes. It is "orthogonal" in the sense that the instruction type and the addressing mode vary independentl ...
architecture, and instructions for complex operations such as
queue __NOTOC__
Queue () may refer to:
* Queue area, or queue, a line or area where people wait for goods or services
Arts, entertainment, and media
*''ACM Queue'', a computer magazine
* ''The Queue'' (Sorokin novel), a 1983 novel by Russian author ...
insertion or deletion, number formatting, and
polynomial
In mathematics, a polynomial is an expression consisting of indeterminates (also called variables) and coefficients, that involves only the operations of addition, subtraction, multiplication, and positive-integer powers of variables. An exa ...
evaluation.
Name
![VAX 11-780 intero](https://upload.wikimedia.org/wikipedia/commons/9/9a/VAX_11-780_intero.jpg)
The name "VAX" originated as an
acronym
An acronym is a word or name formed from the initial components of a longer name or phrase. Acronyms are usually formed from the initial letters of words, as in ''NATO'' (''North Atlantic Treaty Organization''), but sometimes use syllables, as ...
for ''Virtual Address eXtension'', both because the VAX was seen as a 32-bit extension of the older
16-bit
16-bit microcomputers are microcomputers that use 16-bit microprocessors.
A 16-bit register can store 216 different values. The range of integer values that can be stored in 16 bits depends on the integer representation used. With the two mos ...
PDP-11
The PDP-11 is a series of 16-bit minicomputers sold by Digital Equipment Corporation (DEC) from 1970 into the 1990s, one of a set of products in the Programmed Data Processor (PDP) series. In total, around 600,000 PDP-11s of all models were sold, ...
and because it was (after
Prime Computer
Prime Computer, Inc. was a Natick, Massachusetts-based producer of minicomputers from 1972 until 1992. With the advent of PCs and the decline of the minicomputer industry, Prime was forced out of the market in the early 1990s, and by the end of ...
) an early adopter of
virtual memory
In computing, virtual memory, or virtual storage is a memory management technique that provides an "idealized abstraction of the storage resources that are actually available on a given machine" which "creates the illusion to users of a very l ...
to manage this larger address space.
Early versions of the VAX processor implement a "compatibility mode" that emulates many of the PDP-11's instructions, giving it the 11 in VAX-11 to highlight this compatibility. Later versions offloaded the compatibility mode and some of the less used CISC instructions to emulation in the operating system software.
Instruction set
The VAX instruction set was designed to be powerful and
orthogonal
In mathematics, orthogonality is the generalization of the geometric notion of ''perpendicularity''.
By extension, orthogonality is also used to refer to the separation of specific features of a system. The term also has specialized meanings in ...
.
When it was introduced, many programs were written in assembly language, so having a "programmer-friendly" instruction set was important. In time, as more programs were written in
high-level programming language
In computer science, a high-level programming language is a programming language with strong Abstraction (computer science), abstraction from the details of the computer. In contrast to low-level programming languages, it may use natural language ...
s, the instruction set became less visible, and the only ones much concerned about it were compiler writers.
One unusual aspect of the VAX instruction set is the presence of register masks at the start of each subprogram.
These are arbitrary bit patterns that specify, when control is passed to the subprogram, which registers are to be preserved. Since register masks are a form of data embedded within the executable code, they can make linear parsing of the machine code difficult. This can complicate optimization techniques that are applied on machine code.
[
*]
Operating systems
![VAX VMS logo](https://upload.wikimedia.org/wikipedia/commons/3/34/VAX_VMS_logo.svg)
The ''native'' VAX
operating system
An operating system (OS) is system software that manages computer hardware, software resources, and provides common services for computer programs.
Time-sharing operating systems schedule tasks for efficient use of the system and may also in ...
is Digital's VAX/VMS (renamed to
OpenVMS
OpenVMS, often referred to as just VMS, is a multi-user, multiprocessing and virtual memory-based operating system. It is designed to support time-sharing, batch processing, transaction processing and workstation applications. Customers using Ope ...
in 1991 or early 1992 when it was ported to
Alpha
Alpha (uppercase , lowercase ; grc, ἄλφα, ''álpha'', or ell, άλφα, álfa) is the first letter of the Greek alphabet. In the system of Greek numerals, it has a value of one. Alpha is derived from the Phoenician letter aleph , whic ...
, modified to comply with
POSIX
The Portable Operating System Interface (POSIX) is a family of standards specified by the IEEE Computer Society for maintaining compatibility between operating systems. POSIX defines both the system- and user-level application programming interf ...
standards, and ''branded'' as compliant with
XPG4 X/Open group (also known as the Open Group for Unix Systems and incorporated in 1987 as X/Open Company, Ltd.) was a consortium founded by several European UNIX systems manufacturers in 1984 to identify and promote open standards in the field of in ...
by the
X/Open X/Open group (also known as the Open Group for Unix Systems and incorporated in 1987 as X/Open Company, Ltd.) was a consortium founded by several European UNIX systems manufacturers in 1984 to identify and promote open standards in the field of info ...
consortium).
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
A VMScluster, originally known as a VAXcluster, is a computer cluster involving a group of computers running the OpenVMS operating system. Whereas tightly coupled multiprocessor systems run a single copy of the operating system, a VMScluster is l ...
facility.
During the 1980s, a
hypervisor
A hypervisor (also known as a virtual machine monitor, VMM, or virtualizer) is a type of computer software, firmware or hardware that creates and runs virtual machines. A computer on which a hypervisor runs one or more virtual machines is calle ...
for the VAX architecture named ''VMM'' (Virtual Machine Monitor), also known as the ''VAX Security Kernel'', was developed at Digital with the aim of allowing multiple isolated instances of VMS and ULTRIX to be run on the same hardware. VMM was intended to achieve
TCSEC
Trusted Computer System Evaluation Criteria (TCSEC) is a United States Government Department of Defense (DoD) standard that sets basic requirements for assessing the effectiveness of computer security controls built into a computer system. The TCS ...
A1 compliance. By the late 1980s, it was operational on
VAX 8000
The VAX 8000 is a discontinued family of superminicomputers developed and manufactured by Digital Equipment Corporation (DEC) using processors implementing the VAX instruction set architecture (ISA).
The 8000 series was introduced in October 1984 ...
series hardware, but was abandoned before release to customers.
Other VAX operating systems have included various releases of
Berkeley Software Distribution
The Berkeley Software Distribution or Berkeley Standard Distribution (BSD) is a discontinued operating system based on Research Unix, developed and distributed by the Computer Systems Research Group (CSRG) at the University of California, Berk ...
(BSD)
UNIX
Unix (; trademarked as UNIX) is a family of multitasking, multiuser computer operating systems that derive from the original AT&T Unix, whose development started in 1969 at the Bell Labs research center by Ken Thompson, Dennis Ritchie, and ot ...
up to
4.3BSD,
Ultrix
Ultrix (officially all-caps ULTRIX) is the brand name of Digital Equipment Corporation's (DEC) discontinued native Unix operating systems for the PDP-11, VAX, MicroVAX and DECstations.
History
The initial development of Unix occurred on DEC equip ...
-32,
VAXELN
VAXELN (typically pronounced "VAX-elan") is a discontinued real-time operating system for the VAX family of computers produced by the Digital Equipment Corporation (DEC) of Maynard, Massachusetts.
As with RSX-11 and VMS, Dave Cutler was the ...
, and
Xinu
Xinu Is Not Unix (Xinu, a recursive acronym), is an operating system for embedded systems, originally developed by Douglas Comer for educational use at Purdue University in the 1980s. The name is both recursive, and is ''Unix'' spelled backwards ...
. More recently,
NetBSD
NetBSD is a free and open-source Unix operating system based on the Berkeley Software Distribution (BSD). It was the first open-source BSD descendant officially released after 386BSD was forked. It continues to be actively developed and is a ...
and
OpenBSD
OpenBSD is a security-focused, free and open-source, Unix-like operating system based on the Berkeley Software Distribution (BSD). Theo de Raadt created OpenBSD in 1995 by forking NetBSD 1.0. According to the website, the OpenBSD project em ...
have supported various VAX models and some work has been done on porting
Linux
Linux ( or ) is a family of open-source Unix-like operating systems based on the Linux kernel, an operating system kernel first released on September 17, 1991, by Linus Torvalds. Linux is typically packaged as a Linux distribution, which ...
to the VAX architecture. OpenBSD discontinued support for the architecture in September 2016.
History
![DEC-VAX-8350-front-0a](https://upload.wikimedia.org/wikipedia/commons/8/82/DEC-VAX-8350-front-0a.jpg)
The first VAX model sold was the
VAX-11/780
The VAX-11 is a discontinued family of 32-bit superminicomputers, running the Virtual Address eXtension (VAX) instruction set architecture (ISA), developed and manufactured by Digital Equipment Corporation (DEC). Development began in 1976. In ad ...
, which was introduced on October 25, 1977, at the Digital Equipment Corporation's Annual Meeting of Shareholders. Bill Strecker,
C. Gordon Bell
Chester Gordon Bell (born August 19, 1934) is an American electrical engineer and manager. An early employee of Digital Equipment Corporation (DEC) 1960–1966, Bell designed several of their PDP machines and later became Vice President of Eng ...
's doctoral student at
Carnegie Mellon University
Carnegie Mellon University (CMU) is a private research university in Pittsburgh, Pennsylvania. One of its predecessors was established in 1900 by Andrew Carnegie as the Carnegie Technical Schools; it became the Carnegie Institute of Technology ...
, was responsible for the architecture. Many different models with different prices, performance levels, and capacities were subsequently created. VAX
superminicomputer
A superminicomputer, colloquially supermini, is a high-end minicomputer. The term is used to distinguish the emerging 32-bit architecture midrange computers introduced in the mid to late 1970s from the classical 16-bit systems that preceded the ...
s were very popular in the early 1980s.
For a while the VAX-11/780 was used as a standard in
CPU benchmark
Benchmark may refer to:
Business and economics
* Benchmarking, evaluating performance within organizations
* Benchmark price
* Benchmark (crude oil), oil-specific practices
Science and technology
* Benchmark (surveying), a point of known elevati ...
s. It was initially described as a one-
MIPS machine, because its performance was equivalent to an
IBM System/360
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 applica ...
that ran at one MIPS, and the System/360 implementations had previously been de facto performance standards. The actual number of instructions executed in 1 second was about 500,000, which led to complaints of marketing exaggeration. The result was the definition of a "VAX MIPS," the speed of a VAX-11/780; a computer performing at 27 VAX MIPS would run the same program roughly 27 times faster than the VAX-11/780.
Within the Digital community the term ''VUP'' (
VAX Unit of Performance
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.
Other VAX machines an ...
) 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
A VMScluster, originally known as a VAXcluster, is a computer cluster involving a group of computers running the OpenVMS operating system. Whereas tightly coupled multiprocessor systems run a single copy of the operating system, a VMScluster is l ...
. (The performance of the VAX-11/780 still serves as the baseline metric in the
BRL-CAD
BRL-CAD is a constructive solid geometry (CSG) solid modeling computer-aided design (CAD) system. It includes an interactive geometry editor, ray tracing support for graphics rendering and geometric analysis, computer network distributed frame ...
Benchmark, a performance analysis suite included in the BRL-CAD solid modeling software distribution.) The VAX-11/780 included a subordinate stand-alone
LSI-11
The PDP-11 is a series of 16-bit minicomputers sold by Digital Equipment Corporation (DEC) from 1970 into the 1990s, one of a set of products in the Programmed Data Processor (PDP) series. In total, around 600,000 PDP-11s of all models were sold, ...
computer that performed microcode load, booting, and diagnostic functions for the parent computer. This was dropped from subsequent VAX models. Enterprising VAX-11/780 users could therefore run three different Digital Equipment Corporation operating systems: VMS on the VAX processor (from the hard drives), and either RSX-11S or RT-11 on the LSI-11 (from the single density single drive floppy disk).
The VAX went through many different implementations. The original VAX 11/780 was implemented in
TTL
TTL may refer to:
Photography
* Through-the-lens metering, a camera feature
* Zenit TTL, an SLR film camera named for its TTL metering capability
Technology
* Time to live, a computer data lifespan-limiting mechanism
* Transistor–transistor lo ...
and filled a four-by-five-foot cabinet
with a single
CPU. Through the 1980s, the high-end of the family was continually improved using ever-faster discrete components, an evolution that ended with the introduction of the
VAX 9000
The VAX 9000 is a discontinued family of Minicomputers developed and manufactured by Digital Equipment Corporation (DEC) using custom ECL-based processors implementing the VAX instruction set architecture (ISA). Equipped with optional vector proc ...
in October 1989. This design proved too complex and expensive and was ultimately abandoned not long after introduction. CPU implementations that consisted of multiple
emitter-coupled logic
In electronics, emitter-coupled logic (ECL) is a high-speed integrated circuit bipolar transistor logic family. ECL uses an overdriven bipolar junction transistor (BJT) differential amplifier with single-ended input and limited emitter current to ...
(ECL)
gate array
A gate array is an approach to the design and manufacture of application-specific integrated circuits (ASICs) using a prefabricated chip with components that are later interconnected into logic devices (e.g. NAND gates, flip-flops, etc.) according ...
or
macrocell array
Macrocell arrays in PLDs
Programmable logic devices, such as programmable array logic and complex programmable logic devices, typically have a macrocell on every output pin.
Macrocell arrays in ASICs
A macrocell array is an approach to t ...
chips included the
VAX 8600 and 8800 superminis and finally the VAX 9000
mainframe class machines. CPU implementations that consisted of multiple
MOSFET
The metal–oxide–semiconductor field-effect transistor (MOSFET, MOS-FET, or MOS FET) is a type of field-effect transistor (FET), most commonly fabricated by the controlled oxidation of silicon. It has an insulated gate, the voltage of which d ...
custom chips included the 8100 and 8200 class machines. The VAX 11-730 and 725 low-end machines were built using
AMD Am2901 bit-slice
Bit slicing is a technique for constructing a processor from modules of processors of smaller bit width, for the purpose of increasing the word length; in theory to make an arbitrary ''n''-bit central processing unit (CPU). Each of these com ...
components for the ALU.
The
MicroVAX
The MicroVAX is a discontinued family of low-cost minicomputers developed and manufactured by Digital Equipment Corporation (DEC). The first model, the MicroVAX I, was introduced in 1983.(announced October 1983) They used processors that implemen ...
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
Very large-scale integration (VLSI) is the process of creating an integrated circuit (IC) by combining millions or billions of MOS transistors onto a single chip. VLSI began in the 1970s when MOS integrated circuit (Metal Oxide Semiconductor) c ...
chip (or even a few VLSI chips as was later done with the
V-11
The V-11, code-named "Scorpio", is a miniprocessor chip set implementation of the VAX instruction set architecture (ISA) developed and fabricated by Digital Equipment Corporation (DEC).
History
The V-11 was Digital's first VAX microprocess ...
CPU of the VAX 8200/8300). Instead, the MicroVAX I was the first VAX implementation to move some of the more complex VAX instructions (such as the packed decimal and related opcodes) into emulation software. This partitioning substantially reduced the amount of
microcode
In processor design, microcode (μcode) is a technique that interposes a layer of computer organization between the central processing unit (CPU) hardware and the programmer-visible instruction set architecture of a computer. Microcode is a laye ...
required and was referred to as the "MicroVAX" architecture. In the MicroVAX I, the
ALU and registers were implemented as a single
gate-array
A gate array is an approach to the design and manufacture of application-specific integrated circuits (ASICs) using a prefabricated chip with components that are later interconnected into logic devices (e.g. NAND gates, flip-flops, etc.) according ...
chip while the rest of the machine control was conventional logic.
A full
VLSI
Very large-scale integration (VLSI) is the process of creating an integrated circuit (IC) by combining millions or billions of MOS transistors onto a single chip. VLSI began in the 1970s when MOS integrated circuit (Metal Oxide Semiconductor) c ...
(
microprocessor
A microprocessor is a computer processor where the data processing logic and control is included on a single integrated circuit, or a small number of integrated circuits. The microprocessor contains the arithmetic, logic, and control circu ...
) implementation of the MicroVAX architecture arrived with the
MicroVAX II's 78032 (or DC333) CPU and 78132 (DC335) FPU. The 78032 was the first microprocessor with an on-board
memory management unit
A memory management unit (MMU), sometimes called paged memory management unit (PMMU), is a computer hardware unit having all memory references passed through itself, primarily performing the translation of virtual memory addresses to physical ad ...
The MicroVAX II was based on a single, quad-sized processor board which carried the processor chips and ran the
MicroVMS
OpenVMS, often referred to as just VMS, is a multi-user, multiprocessing and virtual memory-based operating system. It is designed to support time-sharing, batch processing, transaction processing and workstation applications. Customers usin ...
or
Ultrix
Ultrix (officially all-caps ULTRIX) is the brand name of Digital Equipment Corporation's (DEC) discontinued native Unix operating systems for the PDP-11, VAX, MicroVAX and DECstations.
History
The initial development of Unix occurred on DEC equip ...
-32
operating system
An operating system (OS) is system software that manages computer hardware, software resources, and provides common services for computer programs.
Time-sharing operating systems schedule tasks for efficient use of the system and may also in ...
s. The machine featured 1 MB of on-board memory and a
Q22-bus interface with
DMA transfers. The MicroVAX II was succeeded by many further MicroVAX models with much improved performance and memory.
Further VLSI VAX processors followed in the form of the V-11,
CVAX
The CVAX is a microprocessor chipset developed and fabricated by Digital Equipment Corporation (DEC) that implemented the VAX instruction set architecture (ISA). The chipset consisted of the CVAX 78034 CPU, CFPA floating-point accelerator, CVAX cl ...
, CVAX SOC ("System On Chip", a single-chip CVAX),
Rigel
Rigel is a blue supergiant star in the constellation of Orion. It has the Bayer designation β Orionis, which is Latinized to Beta Orionis and abbreviated Beta Ori or β Ori. Rigel is the brightest and most massive componentand ...
, Mariah and
NVAX
The NVAX is a CMOS microprocessor developed and produced by Digital Equipment Corporation (DEC) that implemented the VAX instruction set architecture (ISA). A variant of the NVAX, the NVAX+, differed in the bus interface and external cache suppor ...
implementations. The VAX microprocessors extended the architecture to inexpensive
workstation
A workstation is a special computer designed for technical or scientific applications. Intended primarily to be used by a single user, they are commonly connected to a local area network and run multi-user operating systems. The term ''workstat ...
s 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. Sundry graphics were etched onto the CVAX microprocessor die. The phrase ''CVAX... when you care enough to steal the very best'' was etched in broken Russian as a play on a
Hallmark Cards
Hallmark Cards, Inc. is a private, family-owned American company based in Kansas City, Missouri. Founded in 1910 by Joyce Hall, Hallmark is the oldest and largest manufacturer of greeting cards in the United States. In 1985, the company was award ...
slogan, intended as a message to Soviet engineers who were known to be both purloining DEC computers for military applications and
reverse engineering
Reverse engineering (also known as backwards engineering or back engineering) is a process or method through which one attempts to understand through deductive reasoning how a previously made device, process, system, or piece of software accompli ...
their chip design. By the late 1980s, the VAX microprocessors had grown in power to be competitive with discrete designs. This led to the abandonment of the 8000 and 9000 series and their replacement by Rigel-powered models of the
VAX 6000
The VAX 6000 is a discontinued 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-ran ...
, and later by NVAX-powered
VAX 7000
The VAX 7000 and VAX 10000 are a discontinued family of high-end multiprocessor minicomputers developed and manufactured by Digital Equipment Corporation (DEC), introduced in July 1992. These systems use NVAX microprocessors implementing the VAX ...
systems.
In DEC's product offerings, the VAX architecture was eventually superseded by
RISC
In computer engineering, a reduced instruction set computer (RISC) is a computer designed to simplify the individual instructions given to the computer to accomplish tasks. Compared to the instructions given to a complex instruction set comput ...
technology. In 1989 DEC introduced a range of workstations and servers that ran
Ultrix
Ultrix (officially all-caps ULTRIX) is the brand name of Digital Equipment Corporation's (DEC) discontinued native Unix operating systems for the PDP-11, VAX, MicroVAX and DECstations.
History
The initial development of Unix occurred on DEC equip ...
, the
DECstation
The DECstation was a brand of computers used by DEC, and refers to three distinct lines of computer systems—the first released in 1978 as a word processing system, and the latter (more widely known) two both released in 1989. These compri ...
and
DECsystem
DECsystem was a line of server computers from Digital Equipment Corporation. They were based on MIPS architecture processors and ran DEC's version of the UNIX operating system, called ULTRIX. They ranged in size from workstation-style desktop enc ...
respectively, based on processors that implemented the
MIPS architecture
MIPS (Microprocessor without Interlocked Pipelined Stages) is a family of reduced instruction set computer (RISC) instruction set architectures (ISA)Price, Charles (September 1995). ''MIPS IV Instruction Set'' (Revision 3.2), MIPS Technologies, ...
. In 1992 DEC introduced their own RISC instruction set architecture, the
Alpha AXP
Alpha (original name Alpha AXP) is a 64-bit reduced instruction set computer (RISC) instruction set architecture (ISA) developed by Digital Equipment Corporation (DEC). Alpha was designed to replace 32-bit VAX complex instruction set computers ( ...
(later renamed Alpha), and their own Alpha-based microprocessor, the
DECchip 21064, a high performance
64-bit
In computer architecture, 64-bit Integer (computer science), integers, memory addresses, or other Data (computing), data units are those that are 64 bits wide. Also, 64-bit central processing unit, CPUs and arithmetic logic unit, ALUs are those ...
design capable of running OpenVMS.
In August 2000, Compaq announced that the remaining VAX models would be discontinued by the end of the year, but old systems remain in widespread use. The Stromasys
CHARON-VAX and
SIMH
SIMH is a free and open source, multi-platform multi-system emulator. It is maintained by Bob Supnik, a former DEC engineer and DEC vice president, and has been in development in one form or another since the 1960s.
History
SIMH was based on ...
software-based VAX emulators remain available. VMS is now developed by VMS Software Incorporated, albeit only for the
Alpha
Alpha (uppercase , lowercase ; grc, ἄλφα, ''álpha'', or ell, άλφα, álfa) is the first letter of the Greek alphabet. In the system of Greek numerals, it has a value of one. Alpha is derived from the Phoenician letter aleph , whic ...
,
HPE Integrity, and
x86-64
x86-64 (also known as x64, x86_64, AMD64, and Intel 64) is a 64-bit version of the x86 instruction set, first released in 1999. It introduced two new modes of operation, 64-bit mode and compatibility mode, along with a new 4-level paging mod ...
platforms.
Processor architecture
Virtual memory map
The VAX virtual memory is divided into four sections. Each is one gigabyte (in the context of addressing, 2
30 bytes) in size:
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 hardware implemented privilege modes:
Processor status longword
The Process Status Longword contains 32 bits:
VAX-based systems
The first VAX-based system was the
VAX-11/780
The VAX-11 is a discontinued family of 32-bit superminicomputers, running the Virtual Address eXtension (VAX) instruction set architecture (ISA), developed and manufactured by Digital Equipment Corporation (DEC). Development began in 1976. In ad ...
, a member of the
VAX-11
The VAX-11 is a discontinued family of 32-bit superminicomputers, running the Virtual Address eXtension (VAX) instruction set architecture (ISA), developed and manufactured by Digital Equipment Corporation (DEC). Development began in 1976. In a ...
family. The high-end
VAX 8600
The VAX 8000 is a discontinued family of superminicomputers developed and manufactured by Digital Equipment Corporation (DEC) using processors implementing the VAX instruction set architecture (ISA).
The 8000 series was introduced in October 198 ...
replaced the VAX-11/780 in October 1984 and was joined by the entry-level
MicroVAX
The MicroVAX is a discontinued family of low-cost minicomputers developed and manufactured by Digital Equipment Corporation (DEC). The first model, the MicroVAX I, was introduced in 1983.(announced October 1983) They used processors that implemen ...
minicomputers and the
VAXstation
The VAXstation is a discontinued family of workstation computers developed and manufactured by Digital Equipment Corporation using processors implementing the VAX instruction set architecture. VAXstation systems were typically shipped with either ...
workstations in the mid-1980s. The MicroVAX was superseded by the
VAX 4000 The VAX 4000 is a discontinued family of low-end minicomputers developed and manufactured by Digital Equipment Corporation (later Compaq) using microprocessors implementing the VAX instruction set architecture (ISA). The VAX 4000 succeeded the Mic ...
, the VAX 8000 was superseded by the
VAX 6000
The VAX 6000 is a discontinued 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-ran ...
in the late 1980s and the mainframe-class
VAX 9000
The VAX 9000 is a discontinued family of Minicomputers developed and manufactured by Digital Equipment Corporation (DEC) using custom ECL-based processors implementing the VAX instruction set architecture (ISA). Equipped with optional vector proc ...
was introduced. In the early 1990s, the
fault-tolerant
Fault tolerance is the property that enables a system to continue operating properly in the event of the failure of one or more faults within some of its components. If its operating quality decreases at all, the decrease is proportional to the ...
VAXft 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 to ...
was introduced, as were the
Alpha
Alpha (uppercase , lowercase ; grc, ἄλφα, ''álpha'', or ell, άλφα, álfa) is the first letter of the Greek alphabet. In the system of Greek numerals, it has a value of one. Alpha is derived from the Phoenician letter aleph , whic ...
compatible
VAX 7000/10000
The VAX 7000 and VAX 10000 are a discontinued family of high-end multiprocessor minicomputers developed and manufactured by Digital Equipment Corporation (DEC), introduced in July 1992. These systems use NVAX microprocessors implementing the VAX ...
. A variant of various VAX-based systems were sold as the
VAXserver.
SImultaneous Machine ACceSs (SIMACS)
''
System Industries
System Industries, Inc., was an American computer hardware company active from 1968 to 1993. It produced printers and disk drives for minicomputers.
History
The firm was founded in 1968 by Ed Zschau with backing from Brentwood Associates, a pr ...
'' developed an ability to give more than one DEC CPU, but not at the same time, write access to a shared disk. They implemented an enhancement named SImultaneous Machine ACceSs (
SIMACS
RSTS () is a multi-user time-sharing operating system developed by Digital Equipment Corporation (DEC, now part of Hewlett-Packard) for the PDP-11 series of 16-bit minicomputers. The first version of RSTS (RSTS-11, #Versions, Version 1) was implem ...
),
which allowed their special disk controller to set a
semaphore flag
Flag semaphore (from the Ancient Greek () 'sign' and - (-) '-bearer') is a semaphore system conveying information at a distance by means of visual signals with hand-held flags, rods, disks, paddles, or occasionally bare or gloved hands. Informa ...
for disk access, allowing multiple WRITES to the same files; the disk is shared by multiple DEC systems. ''SIMACS'' also existed on PDP-11
RSTS systems.
Canceled systems
Canceled systems include the ''BVAX'', a high-end
emitter-coupled logic
In electronics, emitter-coupled logic (ECL) is a high-speed integrated circuit bipolar transistor logic family. ECL uses an overdriven bipolar junction transistor (BJT) differential amplifier with single-ended input and limited emitter current to ...
(ECL) based VAX, and two other ECL-based VAX models: ''Argonaut'' and ''Raven''. Raven was canceled in 1990. A VAX named ''Gemini'' was also canceled, which was a fall-back in case the LSI-based ''Scorpio'' failed. It never shipped.
Clones
A number of VAX clones, both authorized and unauthorized, were produced. Examples include:
*
Systime Computers Ltd of the United Kingdom produced clones of early VAX models such as the Systime 8750 (equivalent to the VAX 11/750).
* Norden Systems produced the ruggedized, Military-specification MIL VAX series.
* The Hungarian Central Research Institute for Physics (KFKI) produced a series of clones of early VAX models, the TPA-11/540, 560 and 580.
* The SM 52/12 from
Czechoslovakia
, rue, Чеськословеньско, , yi, טשעכאסלאוואקיי,
, common_name = Czechoslovakia
, life_span = 1918–19391945–1992
, p1 = Austria-Hungary
, image_p1 ...
, developed at VUVT
Žilina
Žilina (; hu, Zsolna, ; german: Sillein, or ; pl, Żylina , names in other languages) is a city in north-western Slovakia, around from the capital Bratislava, close to both the Czech and Polish borders. It is the fourth largest city of Sl ...
(today
Slovakia
Slovakia (; sk, Slovensko ), officially the Slovak Republic ( sk, Slovenská republika, links=no ), is a landlocked country in Central Europe. It is bordered by Poland to the north, Ukraine to the east, Hungary to the south, Austria to the s ...
) and produced from 1986 at ZVT
Banská Bystrica
Banská Bystrica (, also known by other alternative names) is a middle-sized town in central Slovakia, located on the Hron River in a long and wide valley encircled by the mountain chains of the Low Tatras, the Veľká Fatra, and the Kremnica Mo ...
(today
Slovakia
Slovakia (; sk, Slovensko ), officially the Slovak Republic ( sk, Slovenská republika, links=no ), is a landlocked country in Central Europe. It is bordered by Poland to the north, Ukraine to the east, Hungary to the south, Austria to the s ...
).
* The East German
VEB Robotron
VEB Kombinat Robotron (or simply Robotron) was the biggest East German electronics manufacturer. It was based in Dresden and employed 68,000 people (1989). It produced personal computers, SM EVM minicomputers, the ESER mainframe computers, sev ...
K 1840 (SM 1710) is a clone of the VAX-11/780 and
Robotron K 1820
The K 1820, full name RVS K 1820 ({{lang, de, Rechnersystem mit virtuellem Speicher, "computer system with virtual memory"), cipher in the SM EVM of the former COMECON countries SM 1720, is a workstation developed in East Germany. Volkseigener B ...
(SM 1720) is a copy of the MicroVAX II.
* The ''SM-1700'' is a Soviet clone of the VAX-11/730, ''SM-1702'' was a clone of MicroVAX II and ''SM-1705'' was a clone of VAX-11/785. These systems ran a variety of clone operating systems -
DEMOS
Demos may refer to:
Computing
* DEMOS, a Soviet Unix-like operating system
* DEMOS (ISP), the first internet service provider in the USSR
* Demos Commander, an Orthodox File Manager for Unix-like systems
* plural for Demo (computer programming)
...
(based on BSD Unix),
MOS VP (based on VAX/VMS) or MOS VP RV (based on VAXELN).
* The NCI-2780 Super-mini, also sold as Taiji-2780, is a clone of the VAX-11/780 developed by North China Institute of Computing Technology in Beijing.
Further reading
*
References
External links
*
DEC MicroprocessorsSimH VAXOpen source emulator that supports VAX architecture
The complete Digital Technical Journals
{{Processor technologies
Computer-related introductions in 1977
DEC mainframe computers
DEC microprocessors
Instruction set architectures
Minicomputers
32-bit computers