The VAX-11 was a family of minicomputers developed and manufactured by Digital Equipment Corporation

Digital Equipment Corporation

Digital Equipment Corporation was a major American company in the computer industry and a leading vendor of computer systems, software and peripherals from the 1960s to the 1990s...

 (DEC) using processors implementing the VAX

VAX

VAX was an instruction set architecture developed by Digital Equipment Corporation in the mid-1970s. A 32-bit complex instruction set computer ISA, it was designed to extend or replace DEC's various Programmed Data Processor ISAs...

 instruction set architecture (ISA). The VAX-11/780 was the first VAX computer.

VAX-11/780

The VAX-11/780, code-named "Star", was introduced on 25 October 1977 at DEC's Annual Meeting of Shareholders. It was the first computer to implement the VAX architecture. The VAX-11/780 central processing unit

Central processing unit

The central processing unit is the portion of a computer system that carries out the instructions of a computer program, to perform the basic arithmetical, logical, and input/output operations of the system. The CPU plays a role somewhat analogous to the brain in the computer. The term has been in...

 (CPU) was built from transistor-transistor logic

Transistor-transistor logic

Transistor–transistor logic is a class of digital circuits built from bipolar junction transistors and resistors. It is called transistor–transistor logic because both the logic gating function and the amplifying function are performed by transistors .TTL is notable for being a widespread...

 (TTL) devices and had a 200 ns cycle time (5 MHz) and a 2 kB cache. Memory and I/O were accessed via the Synchronous Backplane Interconnect

Synchronous Backplane Interconnect

The Synchronous Backplane Interconnect was the internal processor-memory bus used by early VAX computers manufactured by the Digital Equipment Corporation of Maynard, Massachusetts....

 (SBI).

The VAX-11/780 supported 128 kB to 8 MB of memory (2MB initially) through one or two memory controllers. Each memory controller supported 128 kB to 4 MB of memory. The memory was constructed from 4 or 16 kbit metal oxide semiconductor (MOS) RAMs mounted on memory array cards. Each memory controller controlled up to 16 array cards. The memory was protected by error correcting code (ECC).

The VAX-11/780 used the Unibus

Unibus

The Unibus was the earliest of several computer bus technologies used with PDP-11 and early VAX systems manufactured by the Digital Equipment Corporation of Maynard, Massachusetts.-History:...

 and Massbus

Massbus

The Massbus was a high-performance computer input/output bus designed in the 1970s by the Digital Equipment Corporation of Maynard, Massachusetts....

 for I/O. Unibus was used for attaching peripherals and Massbus for disk and tape drives. Both buses were provided by adapters that interfaced the bus to the SBI. All systems came with one Unibus as standard, with up to four supported. Massbus was optional, with up to four supported. The VAX-11/780 also supported Computer Interconnect (CI), a proprietary network to attach disk drives and potentially share them with other VAX computers. Later, this feature was used to connect VAX computers in a VMScluster

VMScluster

A VMScluster 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 loosely coupled: each machine runs its own copy of OpenVMS, but the disk storage, lock...

.

VAX-11/784

The VAX-11/784, code named "VAXimus", was a very rare configuration consisting of four VAX-11/780 CPUs sharing a single MA780 memory unit.

VAX-11/785

The VAX-11/785, code named "Superstar", was introduced in April 1984. It was essentially a faster VAX-11/780, with a CPU cycle time of 133 ns (7.52 MHz) versus the 200 ns (5 MHz) CPU cycle time of the VAX-11/780. The memory subsystem was also upgraded to support higher capacity memory boards.

VAX-11/750

The VAX-11/750, code named "Comet", was a more compact, lower-performance TTL gate array

Gate array

A gate array or uncommitted logic array is an approach to the design and manufacture of application-specific integrated circuits...

-based implementation of the VAX-11/780 introduced in October 1980. The CPU had a 320 ns cycle time (3.125 MHz).

VAX-11/730

Introduced in April 1982, the VAX-11/730, code named "Nebula", was a still-more-compact, still-lower-performance bit slice implementation of the VAX-11/750. Its CPU had a 270 ns cycle time (3.70 MHz).

VAX-11/725

Code named "LCN" ("Low-Cost Nebula"), it was a cost-reduced model of the VAX-11/730. Its CPU had a 270 ns cycle time (3.70 MHz).

Remaining Machines

The Living Computer Museum of Seattle, Washington maintains a VAX-11/780-5 (field-upgraded VAX-11/780) running OpenVMS

OpenVMS

OpenVMS , previously known as VAX-11/VMS, VAX/VMS or VMS, is a computer server operating system that runs on VAX, Alpha and Itanium-based families of computers. Contrary to what its name suggests, OpenVMS is not open source software; however, the source listings are available for purchase...

6.2, which is available to interested parties via telnet upon registration (at no cost) at their website.