MicroVAX 3 (Actually a DSVAX III)

The MicroVAX II’s “successor” was the MicroVAX 3300/3400, which used the KA640 CPU (2.4 VUPS).
The MicroVAX 3 was based on the not-so-much-faster KA650, rated at 2.8 VUPS.
This particular machine is actually a DEC-compatible. The rack, power supply, QBUS cage, bulkheads and most of the QBUS boards are not DEC. The only DEC board is the CPU.

I could not find much information on Digital Systems, but they probably did not go out of business. A company named “DIGITAL SYSTEMS PTY LTD” was registered on 08/12/1978 in Perth, Western Australia, and appears to still be regsitered today (2017).

The rack machine has a Cipher 880 (Model F880640-90-1025U, option C, 1600BPI) magnetic tape drive, and 32 serial ports connectors at the back, which used to connect to two DLZV11 serial interface cards. It originally came with a Fujitsu M2372K 824MB 8″ SMD disk drive.

The Cipher 880, after many fixing attempts, is still inoperable. Inside is a board that actually belongs to a Cipher F891. Tuning attempts have all failed, which leads me to the conclusion it may have a faulty read/write head.


The Fujitsu M2372K has also failed many formatting attempts, using different controllers and different cables. So unfortunately it has been removed and serves as a very, very heavy display item. It is pictured below alongside a 3.5″ disk drive.

The DSVAX III machine currently has:
a KA650 CPU
24MB of RAM
a PERTEC tape controller
Emulex UC07 SCSI controller
SCSI2SD board with a 16GB SD card installed

It currently runs VMS 5.5-1.

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