VAX 4000

The VAX 4000 was a family of low-end minicomputers developed and manufactured by Digital Equipment Corporation (DEC) using microprocessors implementing the VAX instruction set architecture (ISA). The VAX 4000 succeeded the MicroVAX family. It was the last family of low-end VAX systems, as the platform was discontinued by Compaq.

The VAX 4000 Model 300, code-named "Pele", was introduced on 9 July 1990 at DECworld in Boston, Massachusetts, replacing the MicroVAX 3800 and 3900. It used the time-sharing KA670-AA CPU module containing a 35.71 MHz (28 ns cycle time) Rigel chip set with a 128 KB external secondary cache protected by ECC built from 84 ns SRAM. It supported one to four MS670-BA (32 MB) or MS670-CA (64 MB) memory modules for 32 to 256 MB of memory. Q-bus was used for expansion. The Model 300 could be upgraded to a Model 400, Model 500 or Model 600 by replacing the backplane, CPU and memory module(s).

VAX 4000 Model 200, code-named "Spitfire", was introduced in January 1991 as replacement for the MicroVAX 3400. It was positioned beneath the VAX 4000 Model 300. It used the KA660 CPU module containing a 28.57 MHz (35 ns cycle time) SOC microprocessor. It supported 16 to 64 MB of memory.

The VAX 4000 Model 500, code-named "Omega/N", was introduced on 30 October 1991, with availability in December 1991. It succeeded the VAX 4000 Model 300, but the older system remained available as a lower cost alternative. It used the KA680 CPU module containing a 71.43 MHz (14 ns cycle time) NVAX microprocessor with 128 KB of external tertiary cache.

The VAX 4000 Model 100, code-named "Cheetah-Q", is an entry-level VAX 4000 system introduced on 7 July 1992. It used the KA52 CPU module containing a 72 MHz (14 ns cycle time) NVAX microprocessor with 128 KB of external tertiary cache. It supported up to 128 MB of memory.

The VAX 4000 Model 400, code-named "Omega", was a distributed server, positioned as a mid-range VAX 4000 system, introduced on 7 July 1992. It used the KA675 CPU module containing a 63 MHz (16 ns) NVAX microprocessor with 128 KB of external tertiary cache. It supported 16 to 512 MB of memory.

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