Editing Digital Equipment Corporation (section)

=== VAX (1977) ===
[[File:Locale_RS6_LCM - DEC VAX 11-780-5 - 01.jpg|thumb|DEC VAX 11/780-5 at [[Living Computers: Museum + Labs]] ]]
{{Main|VAX}}

The introduction of [[semiconductor memory]] in the early 1970s, and especially [[dynamic RAM]] shortly thereafter, led to dramatic reductions in the price of memory as the effects of [[Moore's Law]] were felt. Within years, it was common to equip a machine with all the memory it could address, typically 64&nbsp;KB on 16-bit machines. This led vendors to introduce new designs with the ability to address more memory, often by extending the address format to 18 or 24 bits in machines that were otherwise similar to their earlier 16-bit designs.{{efn|An example is the DG Nova 840, which used a 17-bit format, up from the previous 15-bits.}}

In contrast, DEC decided to make a more radical departure. In 1976, they began the design of a machine whose entire architecture was expanded from the 16-bit PDP-11 to a new 32-bit basis. This would allow the addressing of very large memories, which were to be controlled by a new [[virtual memory]] system, and would also improve performance by processing twice as much data at a time. The system would, however, maintain compatibility with the PDP-11, by operating in a second mode that sent its 16-bit words into the 32-bit internals, while mapping the PDP-11's 16-bit memory space into the larger virtual 32-bit space.<ref name=VAX/>

The result was the [[VAX]] architecture, where VAX stands for Virtual Address eXtension (from 16 to 32 bits). The first computer to use a VAX CPU was the [[VAX-11/780]], announced in October 1977, which DEC referred to as a ''[[superminicomputer]]''. Although it was not the first 32-bit minicomputer, the VAX-11/780's combination of features, price, and marketing almost immediately propelled it to a leadership position in the market after it was released in 1978. VAX systems were so successful that in 1983, DEC canceled its [[Jupiter project]], which had been intended to build a successor to the PDP-10 mainframe, and instead focused on promoting the VAX as the single computer architecture for the company.<ref name=VAX>{{cite book| title = Electronic Business| url = https://books.google.com/books?id=W7skAQAAIAAJ&pg=PA76| year = 1984| publisher = Cahners| page = 76 }}</ref>{{r|bellstreckerpdp11vaxalpha}}

Supporting the VAX's success was the [[VT52]], one of the most successful [[Computer terminal|smart terminals]]. Building on earlier less successful models, the [[VT05]] and [[VT50]], the VT52 was the first terminal that did everything one might want in a single inexpensive chassis. The VT52 was followed by the even more successful [[VT100]] and its follow-ons, making DEC one of the largest terminal vendors in the industry. This was supported by a line of inexpensive [[computer printer]]s, the [[DECwriter]] line. With the VT and DECwriter series, DEC could now offer a complete top-to-bottom system from computer to all peripherals, which formerly required collecting the required devices from different suppliers.

The VAX processor architecture and family of systems evolved and expanded through several generations during the 1980s, culminating in the [[NVAX]] [[microprocessor]] implementation and [[VAX 7000/10000]] series in the early 1990s.<ref name="nvax">{{cite web|url=http://simh.trailing-edge.com/semi/nvax.html|title=DEC Microprocessors: NVAX (1991)}}</ref>