MicroVAX

The MicroVAX is a discontinued family of low-cost minicomputers developed and manufactured by Digital Equipment Corporation (DEC).

[3][4] The MicroVAX I, code-named Seahorse,[5] introduced in October 1984, was one of DEC's first VAX computers to use very-large-scale integration (VLSI) technology.

Two variants of the floating point chips were supported, with the chips differing by the type of floating point instructions supported, F and G, or F and D. The system was implemented on two quad-height Q-bus cards - a Data Path Module (DAP) and Memory Controller (MCT).

The module also contained 1 MB of memory, an interval timer, two ROMs for the boot and diagnostic facility, a DZ console serial line unit and a time-of-year clock.

A 50-pin connector for a ribbon cable near the top left corner of the module provided the means by which more memory was added to the system.

KA620 referred to a single-board MicroVAX II designed for automatic test equipment and manufacturing applications which only ran DEC's real-time VAXELN operating system.

[9] Mira referred to a fault-tolerant configuration of the MicroVAX II developed by DEC's European Centre for Special Systems located in Annecy in France.

The system could have a Shugart-based harddrive with ST412 interface and MFM encoding and had a built in 5.25-inch floppy drive (named RX33 in DEC jargon) for software distribution and backup.

The performance improvements over the MicroVAX II resulted from the increased clock rate of the CVAX chip set, which operated at 11.11 MHz (90 ns cycle time) along with a two-level, write-through caching architecture.

[20] A variant of the MicroVAX 3800, the rtVAX 3800, was intended for real-time computing (RTC) applications such as computer-aided manufacturing (CAM).

These systems used the KA655 CPU module, which contained a 16.67 MHz (60 ns cycle time) CVAX chip set.