CPU and Backplane

vtVAX allows to replace almost all VAX models that have been created during the life-cycle of the VAX product line.

vtVAX is available in two CPU speed variants:

  • Standard CPU speed (20 - 30 VUPS, depending on the host)
  • Accelerated CPU (100+ VUPS, depending on the host)

The performance of the virtual VAX system is determined by the host hardware and the workload of all of the emulated systems running on the host. The performance is not limited by the model of VAX system being emulated.

Virtual VAX memory

vtVAX supports up to 128, 256 or 512 MB virtual VAX memory, depending on the selected vtVAX product.

Storage subsystem

vtVAX can configure virtual read/write disks, CD-ROM drives, and tape devices. These virtual devices may be mapped to physical SCSI devices from the VAX system or to logical drives implemented as container files within the host PC file system. These container files may be located on any type of storage attached to the host: directly attached drives, including SCSI, SATA, SAS, USB, solid state, or CD/DVD; iSCSI, NAS, SAN, or cloud.

Emulated Qbus based systems allow for the configuration of four virtual MSCP disk controllers, each supporting 32 drives (DI, DK, and DU devices). SCSI bus systems support the configuration of two virtual SCSI controllers, each supporting eight disk devices. A single virtual tape controller may be configured with up to 16 tape drives. VAX 7000 systems may be configured with up to eight DSSI controllers.

For performance and reliability reasons, we recommend using VAX storage media only for initial system setup or retrieval of archived data. The PC host's modern disk drives have much higher reliability, performance, and data capacity, less accumulated wear, are cheaper initially, and much less expensive to operate and maintain.

Multiple logical disks may be stored on a single host disk, providing for storage consolidation without changing the VMS file system. VAX tape operations using logical tape drives transfer data at disk speeds without the physical media errors commonly experienced with tape storage.

Network subsystem

vtVAX supports virtual DELQA, DEQNA, SGEC (EZ), or DEMNA (EX) Ethernet interfaces, depending on the processor model being emulated. A maximum of two DELQA/DEQNA adapters or one SGEC adapter may be configured (all three may be configured when emulating a VAX 4000 system). Each virtual Ethernet adapter can be mapped to a physical Ethernet interface on the host system. Or a virtual switch to allow multiple virtual adapters to share a single physical host link.

Network interfaces are not limited by the 10 Mbps or half duplex limitations of a physical VAX system. The network interfaces can be set in any mode supported by the vtVAX host, usually 1 or 10 GBps (full duplex). In most cases this allows the virtual VAX system to achieve much higher network throughput than the physical system it replaces.

Serial lines

vtVAX emulates the DHQ11, DHV11, CXA16, CXB16, and CXY08 serial interfaces, to a maximum of 32 ports. Each configured serial port requires a dedicated connection on the host: a serial COM port (on-board or PCI serial interface) or a Telnet connection. Telnet connections are presented as virtual devices. Only the virtual ports actually used need to be configured (i.e., if you are emulating a DHV11 and only require two of the eight ports, only two physical ports are required).

  • a VT-like device connected to the host
  • Any VT-terminal emulator via Ethernet
  • Pseudo terminal on the host system


When emulating a Qbus based system, a single virtual VCB02 graphics controller can be configured, allowing the host monitor to be used as the display device for the virtual VAX.

Supported VAX operating systems

Operating system versions VAX/VMS V4.3 through OpenVMS V7.3 are supported in the virtualized processors, in accordance with the appropriate VAX/VMS or OpenVMS Software Product Description.

vtVAX virtualized systems can be configured as VAX-cluster or OpenVMS Cluster members using Ethernet (NI) or emulated DSSI ("shared disk") interconnects. The Maintenance Operations Protocol (MOP) is supported for maintenance operations and remote booting

Host computer recommendations

For vtVAX we recommend a PC/Server with Intel or AMD processor (64-bit) of recent design and a CPU frequency of at least 2.4 GHz.(Intel Xeon E5v3, i7 gen 6, Opteron A).

Two host CPU-cores for every virtual VAX CPU. Hyper-threading is not supported.

2 GB Host memory per virtual VAX

See the Host Computer Recommendations page for more details.

User documentation

User documentation is included in the product and accessible via the Management Interface in HTML and PDF format.

Software license protection

vtVAX is software available under End-User License. The license is stored on a physical license key (Smart Card technology) with USB-connector for compatibility reasons.

Multiple vtVAX licenses can be combined on a single License Key. The license mechanism is network capable and be made available across the company network to the virtual Alphas and VAXes in the network.

Product items

Base License.
Virtualizes 1 single CPU VAX system with up to 128, 256 or 512 MB virtual memory and all virtualized devices (varies per virtual VAX-model)

Software Support Service.
Access to the support desk with questions or problems and free upgrades to the latest version of the product you purchased.

Disaster Recovery License.
720 Hours of vtVAX usage that can be used for failover when the original license is unavailable or damaged.

vtVAX virtualizes:

  • VAX: 4000-90, 4000-100, 4000-105A, 4000-200
  • VAXserver: 3600, 3900
  • MicroVAX: II, 3100-90, 3100-95, 3600, 3900
  • VAXstation: II, 3600, 3900

Product details

  • 1 VAX CPU
  • 128, 256 or 512 MB VAX memory
  • MSCP storage (depends on VAX model)
  • SCSI storage (depends on VAX model)
  • DSSI storage (depends on VAX model)
  • Ethernet Adapters
  • - SGEC (EZ)
  • Serial Lines
  • - 1 - 4 on-board (incl OPA0)
  • - up to 32 ports via virtual adapters

More details:

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