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A VAX-11/780

The VAX-11 is a family of minicomputers developed and manufactured by Digital Equipment Corporation (DEC) using processors implementing the VAX instruction set architecture (ISA). The VAX-11/780 was the first VAX computer.



The VAX-11/780, code-named "Star", was introduced on 25 October 1977 at DEC's Annual Meeting of Shareholders.[1] It was the first computer to implement the VAX architecture. The VAX-11/780 central processing unit (CPU) was built from transistor-transistor logic (TTL) devices had a 200 ns cycle time (5 MHz) and a 2KB cache. Memory and I/O was accessed via the Synchronous Backplane Interconnect (SBI).

The VAX-11/780 supported 128 KB to 8 MB of memory 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 and Massbus 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 11/782, code named "Atlas", is a dual-processor VAX-11/780.


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


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.[2]


The VAX-11/787 was a dual-processor variant of the VAX-11/785.



The VAX-11/750, code named "Comet" is a more-compact, lower-performance TTL gate array-based implementation of the VAX-11/780 introduced in October 1980. The CPU had a 320 ns cycle time (3.125 MHz).


A ruggedized rack-mount VAX-11/750.


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).


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).

VAX 11/788

The VAX-11/788 was code named "VISQ".


  1. ^ Digital Equipment Corporation. VAX OpenVMS at 20.
  2. ^ DIGITAL Computing Timeline


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