As shown in the VAX Overview and Classification, all VAX CPUs can be divided into the Big 4, BI/XMI VAXen, Q22-bus MicroVAXen, and BabyVAXen.

The Big 4

The Big 4 form the core of the VAX CPU support and VAX hardware support in general in 4.3BSD. All 4 have been fully supported since the very first 4.3BSD release. The Quasijarus Consortium has an obligation to the Red 4.3BSD Daemon to keep and maintain this support forever. This includes the 730, the support for which has been dropped by many of the lesser VAX UNIX projects.

The only future hardware support expansion planned for the Big 4 is the support for CI780 and CI750 adapters. See MSCP and Cluster Interfaces.


The 4.3BSD-Tahoe release introduced support for VAX 8200, and it appears in the 4.3BSD-Quasijarus0b release. It is usable with restrictions. The main restriction is limited support for BI devices, see Buses and Peripherals and MSCP and Cluster Interfaces.

Once we switch to the new SCA framework and the new booting and installation mechanism, however, it will probably be pretty easy for the Quasijarus Consortium to develop full support for VAX 8200 and VAX 6200/6300. Support for higher VAX 6000 CPU boards will also be easy to develop given a machine or board to test on and the appropriate manuals. The bigger BI/XMI VAXen, i.e., the 8800 and 9000 series, can also be supported, but the scarcity and unwieldly size of the hardware and the resulting difficulty of obtaining it and working on it are likely to be the main obstacles.

BSD UNIX does not support symmetric multiprocessing on any machine, and this is unlikely to change soon.

Q22-bus MicroVAXen

The support for the first sane Q22-bus MicroVAX, KA630 MicroVAX II, started with the 4.3BSD release. However, in that release it was unfinished and not practically usable, since it lacked bootstraps and standalone system support and the kernel reportedly had some show-stopping bugs. 4.3BSD-Quasijarus has had full production quality support for KA630 and KA650/655, including direct installation from the distribution tape, since 4.3BSD-Quasijarus0a.

The next release is planned to include KA640 and KA660 support. KA670 and the KA680 family can be easily supported given machines to test on and copies of DEC documents EK-KA670-TM and EK-KA680-TM, respectively. However, this does not include support for on-board non-Q-bus Ethernet and DSSI ports on these CPUs. Supporting those is a separate problem, see Buses and Peripherals.


With the exception of KA52 (VAX 4100), BabyVAXen do not have Q-bus or any other expansion bus. They only have on-board devices, none of which are currently supported. Since supporting a machine requires supporting at least the console, some disk storage for the system to reside on, and some tape storage to install the system from, BabyVAXen cannot be supported until their on-board devices are supported. See Buses and Peripherals.

@(#)cpu.html 1.1 03/12/18

Michael Sokolov