Editing VAX (section)

== History ==
[[File:DEC-VAX-8350-front-0a.jpg|thumb|VAX 8350 front view with cover removed]]

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.<ref>{{cite web |url=https://www.old-computers.com/history/detail.asp?n=20&t=3 |title=VAX 11/780, The First VAX System (October 1977)}}</ref> Bill Strecker, [[C. Gordon Bell]]'s doctoral student at [[Carnegie Mellon University]], was responsible for the architecture.<ref>{{Cite book |url=https://books.google.com/books?id=aWTtMyYmKhUC&q=%22Bill+Strecker%22+vax+designer |title=Portraits in Silicon |last=Slater |first=Robert |publisher=MIT Press |year=1987 |page=[https://books.google.com/books?id=aWTtMyYmKhUC&pg=PA213&lpg=PA213&dq=%22Bill+Strecker%22+vax+designer 213] |isbn=978-0-262-69131-4}}</ref> Many different models with different prices, performance levels, and capacities were subsequently created. VAX [[superminicomputer]]s were very popular in the early 1980s.

For a while the VAX-11/780 was used as a standard in [[central processing unit|CPU]] [[Benchmark (computing)|benchmark]]s. It was initially described as a one-[[million instructions per second|MIPS]] machine, because its performance was equivalent to an [[IBM System/360]] 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]]) 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 [[VMScluster|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.) The VAX-11/780 included a subordinate stand-alone [[PDP-11|LSI-11]] 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 [[Transistor-transistor logic|TTL]] and filled a four-by-five-foot cabinet<ref name=chm11780>{{cite web |title=VAX 11/780 Computer: CPU |url=http://www.computerhistory.org/revolution/mainframe-computers/7/182/736 |publisher=Computer History Museum |access-date=October 24, 2012}}</ref> with a single [[Central processing unit|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]] 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]] (ECL) [[gate array]] or [[macrocell array]] chips included the [[VAX 8000|VAX 8600 and 8800]] superminis and finally the VAX 9000 [[mainframe computer|mainframe]] class machines. CPU implementations that consisted of multiple [[MOSFET]] custom chips included the 8100 and 8200 class machines. The VAX 11-730 and 725 low-end machines were built using [[AMD Am2900|AMD Am2901]] [[bit-slice]] components for the ALU.

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 [[DEC V-11|V-11]] 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]] required and was referred to as the "MicroVAX" architecture. In the MicroVAX I, the [[arithmetic logic unit|ALU]] and registers were implemented as a single [[Gate array|gate-array]] chip while the rest of the machine control was conventional logic.

A full [[VLSI]] ([[microprocessor]]) implementation of the MicroVAX architecture arrived with the [[MicroVAX 78032|MicroVAX II's 78032]] (or DC333) CPU and 78132 (DC335) FPU. The 78032 was the first microprocessor with an on-board [[memory management unit]]<ref>{{cite web|url=http://simh.trailing-edge.com/semi/uvax.html|website=Computer History and Simulation|title=MicroVAX II (1985)}}</ref> The MicroVAX II was based on a single, quad-sized processor board which carried the processor chips and ran the [[OpenVMS#Origin and name changes|MicroVMS]] or [[Ultrix]]-32 [[operating system]]s. The machine featured 1 MB of on-board memory and a [[Q-Bus|Q22-bus]] interface with [[Direct memory access|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]], CVAX SOC ("System On Chip", a single-chip CVAX), [[Rigel (microprocessor)|Rigel]], Mariah and [[NVAX]] implementations. The VAX microprocessors extended the architecture to inexpensive [[workstation]]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]] slogan, intended as a message to Soviet engineers who were known to be both purloining DEC computers for military applications and [[reverse engineering]] their chip design.<ref>{{cite web|website=micro.magnet.fsu.edu|url=http://micro.magnet.fsu.edu/creatures/pages/russians.html|title=Steal the best|access-date=January 30, 2008}} The Russian phrase was: {{lang|ru|СВАКС... Когда вы забатите довольно воровать настоящий лучший}}</ref><ref>{{cite web|url=http://simh.trailing-edge.com/semi/cvax.html|website=Computer History and Simulation|title=CVAX (1987)|access-date=January 30, 2008}}</ref> 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]], and later by NVAX-powered [[VAX 7000]] systems.

In DEC's product offerings, the VAX architecture was eventually superseded by [[RISC]] technology. In 1989 DEC introduced a range of workstations and servers that ran [[Ultrix]], the [[DECstation]] and [[DECsystem]] respectively, using processors from [[MIPS Computer Systems]]. In 1992 DEC introduced their own RISC instruction set architecture, the [[DEC Alpha|Alpha AXP]] (later renamed Alpha), and their own Alpha-based microprocessor, the [[Alpha 21064|DECchip 21064]], a high performance [[64-bit]] design capable of running OpenVMS.

In August 2000, Compaq announced that the remaining VAX models would be discontinued by the end of the year,<ref>{{cite web|url=http://www.compaq.com/alphaserver/vax/vax_letter_final.html |title=VAX Systems: A letter from Jesse Lipcon |archive-url=https://web.archive.org/web/20000815201016/http://www.compaq.com/alphaserver/vax/vax_letter_final.html |archive-date=August 15, 2000 |url-status=dead}}</ref> but old systems remain in widespread use.<ref>{{Cite web|url=https://www.pcworld.com/article/468250/if-it-aint-broke-dont-fix-it-ancient-computers-in-use-today.html|title=If It Ain't Broke, Don't Fix It: Ancient Computers in Use Today|website=PCWorld|access-date=October 11, 2021}}</ref> The Stromasys [[Charon (software)|CHARON-VAX]] and [[SIMH]] software-based VAX emulators remain available. VMS is now developed by VMS Software Incorporated, albeit only for the [[DEC Alpha|Alpha]], [[HPE Integrity Servers|HPE Integrity]], and [[x86-64]] platforms.