Digital Equipment Corporation VAXserver 3500  
Written by Accutron on 2010-01-21  


The DEC VAXserver 3500 is a high end variant in the MicroVAX III series. Codenamed 'Mayfair', the VAXserver 3500 was introduced in September 1987 and makes use of a 11.11MHz CVAX chipset. The CVAX microprocessor is a second-generation single-chip VAX ISA implementation, containing 134,000 transistors on a 9.4 x 7.4mm die, and fabricated using DEC's first-generation CMOS process. The entire CVAX chipset consists of six chips: the CVAX 78034 CPU, CFPA floating-point accelerator, CVAX clock chip, CVAX System Support Chip (CSSC), CVAX Memory Controller (CMCTL), and the CVAX Q-Bus Interface Chip (CQBIC).

Due to DEC's obnoxious software licensing schemes, the VAX 3500 platform was offered in a number of insignificantly different variants. The two key variants are the MicroVAX 3500 and VAXserver 3500, which are virtually identical except for a slight difference in the CPU microcode which determines whether the system can run single-user or multi-user software. A MicroVAX 3500 can be easily converted to a VAXserver 3500, simply by swapping its KA650-AA CPU card for a KA650-BA card.

The VAXserver 3500 is a class of system once referred to as a 'supermini'. Such systems evolved directly from traditional minicomputers of the 1960s and 1970s, but typically featured a 32-bit word, elaborate instruction sets and other advanced characteristics more commonly seen on larger systems.

The original VAX-11/780 is considered to be the definitive supermini; the VAX architecture completely dominated the mid-range computer market for about 15 years, beginning in 1978. This period was marked by a rapid decline in the minicomputer industry, which would ultimately destroy DEC and many other notable minicomputer manufacturers, such as Data General and Prime Computer. The only major minicomputer manufacturer to survive the culling would be Hewlett-Packard, which ultimately devoured the carcasses of its various competitors. The VAXserver 3500 is among the last minicomputers ever built. Beginning in the late 1980s, the mid-range computer market would be taken over by 64-bit RISC servers and desktop workstations, and the minicomputer form factor would be abandoned entirely.


DEC VAXserver 3500 32-bit minicomputer.

VAXserver 3500, card cage.

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