Virtualization Solutions for
OpenVMS & Tru64 Systems

VAX and Alpha Hardware Emulation on a PC Host

HW Replacement + Server Consolidation + Business Continuity

Improve Reliability * Decrease Cost * Enhance Productivity

vtVAX Products

vtVAX Product Highlights

Operating System

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 (SPD).


vtVAX virtualized systems can be configured as VAXcluster 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


vtVAX can emulate any of the following VAX processors:

  • VAX: 4000-90, 4000-100, 4000-105A, 4000-200, 7000 models 610-640 (models 650 and 660 on Bare Metal only)
  • VAXserver: 3600, 3900
  • MicroVAX: II, 3100-90, 3100-95, 3600, 3900
  • VAXstation: II, 3600, 3900

Emulated systems can be configured with up to 512 MB of memory, subject to configuration constraints of the particular hardware model. Some emulated models may allow for more memory than can be configured on the original VAX system. VAX 7000 emulations may be configured with up to 3.5 GB of memory on Bare Metal or up to 1 GB on Windows.

The model of processor being emulated determines the types of storage, network, and serial devices that can be configured in the virtual environment.

The performance of the virtual VAX system is determined by the hardware configuration of the host system 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.

The models listed above were chosen for emulation because they can replace systems with a wide range of VMS operating system versions, DEC software license types, and device configurations. Your vtVAX reseller will assist you with conducting a system inventory that will help us determine which vtVAX solution best meets your requirements.


Your existing software license PAKs work in the virtual processor environment just as they do when running on a physical VAX processor. HP and Oracle require that transfer licenses be obtained in order to run their software products in a virtualized environment. For other software products, please contact a vtVAX reseller vtVAX reseller (listed on the Contact page of our web site) for guidance.


vtVAX has the capability to 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 4 virtual MSCP disk controllers, each supporting 32 drives (DI, DK, and DU devices). SCSI bus systems support the configuration of 2 virtual SCSI controllers, each supporting 8 disk devices. One virtual tape controller may be configured with up to 16 tape drives. VAX 7000 systems may be configured with up to 8 DSSI controllers.

For performance and reliability reasons, we recommend use of 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 container files may be stored on a single PC drive, providing for storage consolidation without changing the OpenVMS file system. VAX tape operations using logical tape drives transfer data at disk speeds without the physical media errors commonly experienced with tape storage. The container files for logical disk and tape volumes may be copied or backed up using standard Windows or vtMonitor utilities.


vtVAX supports virtual DELQA, DEQNA, SGEC (EZ), or DEMNA (EX) Ethernet interfaces, depending on the processor model being emulated. A maximum of two (2) DELQA/DEQNA adapters or one (1) SGEC adapter may be configured (all three may be configured when emulating a VAX 4000 system). VAX 7000 systems may be configured with up to 4 virtual DEMNA adapters. Each virtual Ethernet adapter is mapped to a dedicated physical Ethernet interface on the host system. On the Bare Metal platform a virtual switch may be used to allow multiple virtual adapters to share a single physical interface.

Network interfaces are not constrained by the 10 Mbit/sec, half duplex limitations of a physical VAX system; the physical interfaces can be configured in any mode supported by the device and the PC host operating system, usually 100 Mbit/sec or 1000 Mbit/sec 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 2 of the 8 ports, only 2 physical ports are required).


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