MicroVAX III

MicroVAX III was the generic name erroneously given to the 3rd-generation series of DEC VAX microcomputers by the computer press. It was not a formal DEC product name; the confusion probably occurred because the KA630 CPU of the MicroVAX II was succeeded by the KA650 CPU‎‎, and people assumed the name of the VAX systems which used it followed.

The KA650 CPU‎‎ was implemented in VLSI.

These computers used the QBUS for their I/O only; main memory traffic used the KA650 Main Memory System‎‎, which used a special bus carried on over the back connectors as well as the CD interconnect of the QBUS backplane. (The address space of the QBUS was limited to 4MB, and the data section is only 16 bits wide, so there were good reasons for partially replacing it.)

Systems which used the KA650 included:

• MicroVAX 3500
• MicroVAX 3600
• VAXserver 3500
• VAXserver 3600
• VAXstation 3200
• VAXstation 3500

External links

• VAX 650 - documentation at Bitsavers