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DEC VAX Computers, Powered by VAX/VMS Operating System: A Powerhouse in ComputingDEC VAX refers to the 32-bit minicomputers that Digital Equipment Corporation produced from 1977 to 2000. It stands for Virtual Address eXtension. VAX was originally built for science and academia, but spread to federal and government agencies, finance, telecom, manufacturing, and other enterprises.
DEC VAX hardware had a unique architecture that includes virtual memory, CISC architecture, its remarkable instruction set and data types, I/O implementation, and addressing modes.
It has many features like backward compatibility with PDP-11, a versatile instruction set with orthogonality, its cost-effective performance, networking and file sharing, its model variety and compatibility, multiprocessing, reliability and low maintenance, the immense peripheral support, better software development and running, and its powerful VAX/VMS operating system (later, OpenVMS).
The VAX/VMS OS was also greatly effective in making VAX a force to reckon with. Its virtual memory management, multitasking, clustering, process isolation, and strong security features were responsible for empowering VAX throughout the 1980s and 1990s. Now that it is a legacy system, you can use emulation to maintain your workload without complete migration.
ArticleDEC VAX is a set of 32-bit minicomputers released by Digital Equipment Corporation that ran from 1977 to 2000. It became a sensation in the 1980s and 1990s, before the 64-bit Alpha computers took over.
It succeeded the PDP-11 computers, which were 16-bit and limited in their memory capabilities for the time. VAX computer systems were perfect as the next step, bridging the gap between powerful IBM mainframes that came before and the personal computers that came later.
DEC VAX computers include a wide range of machines, from low-cost minicomputers and workstations to high-end and low-end superminicomputers. In fact, they form one of the longest lines of computers produced by DEC. DEC VAX was also known for its use of “virtual memory”.
VAX primarily uses the VAX/VMS operating system (later named OpenVMS, when it was ported to Alpha). Also announced in 1977 along with VAX (11/780), it was known for exceptional security, availability, and reliability.
This blog will discuss the features of both DEC VAX and VAX/VMS, as well as their use cases and advantages. We will also discuss why they went into the legacy system section of computers and how you can continue using them exactly as before.
VAX stands for Virtual Address eXtension. As we said earlier, it refers to a series of 32-bit minicomputers designed by DEC. The series started with the VAX-11/780 in 1977 – the first of the DEC VAX models released.
VAX computers were produced for a decade and a half, with the final model launched in 1992. After that, DEC moved on to the Alpha system entirely. In total, there were over a hundred models created.
These machines were significant in computing history. They bridged the gap between early mini/superminicomputers and mainframes. The long production run of VAX demonstrates its impact on the industry.
Originally, DEC VAX computers were made for the science and engineering world. Early on, in the 1980s, they were also used for accounting and finance. They used the VAX/VMS or OpenVMS operating system, which we will elaborate on later.
The VAX architecture was built on a CISC design, featuring a variable-length instruction format and a wide range of addressing modes. It has a highly orthogonal instruction set. It also includes complex operations such as queue insertion or deletion, number formatting, and polynomial evaluation.
To understand DEC VAX entirely, we must start with its architecture. Here are six important points about these processors.
DEC VAX was one of the first commercially successful computers to implement virtual memory.
It is a method of employing secondary storage combined with RAM for executing large programs. This allows a user to build and run a program that requires more memory than the limited main memory available. With the help of virtual memory, VAX computer systems can use secondary storage as part of the primary storage.
DEC VAX splits the virtual memory into four parts. Each part is one gigabyte in size. These sections are used for different purposes (user process space, process stacks, operating system, reserved). This division makes memory management more efficient. It also kept processes separate from each other.
This virtual memory feature enabled users to run tasks that seemed impossible to execute. It made writing programs easier because programmers did not have to divide them into segments to fit the limited memory available at the time.
The VAX architecture is a classic example of the Complex Instruction Set Computing (CISC) design. Hence, they have a rich, complex instruction set that allows for the efficient execution of various operations.
VAX computer systems use variable-length instruction formats that support numerous addressing modes. Such flexibility enhances their task-handling capabilities. The architecture features 16 general-purpose registers that are labeled R0 to R15.
The last four are the argument pointer, frame pointer, stack pointer, and program counter. This setup aids in efficient memory management. There are also four hardware-implemented privilege or access modes (Kernel, Executive, Supervisor, and User) and process status longword registers.
The DEC VAX computers support various data types and formats, including:
DEC VAX instructions are designed to be orthogonal, which means that any addressing mode can be used with any instruction. This flexibility comes from a variable-length instruction format (more than 300) and various addressing modes (22 in number), such as register mode, autoincrement, autodecrement, and base relative addressing.
As we mentioned, the registers have special roles. The system handles various data types, including integers, characters, and floating-point numbers.
VAX instruction mnemonics combine different elements to create a wide range of operations, such as:
Also, register masks are a standout feature. They are at the start of each subprogram and show which registers to save and restore.
The DEC VAX architecture handles input and output through special controllers. These I/O device controllers are key to managing data flow, with each having its own set of registers that are used for control and status monitoring.
The DEC VAX system maps these registers into a specific area called the I/O space. It is a part of the overall address space. By doing this, the CPU can easily interact with I/O devices, making I/O management more efficient. This approach streamlines communication between the CPU and the peripherals.
Addressing modes determine how the system finds data in memory, which enables flexibility and efficient memory access.
Modernizing your legacy system, including VAX, can be tough but not impossible. Here's how.
Back in its heyday, DEC VAX was renowned for its unique advantages owing to its features. Let us look at the capabilities of the DEC VAX hardware.
VAX computer systems maintained compatibility with PDP-11. This feature protected existing software investments. Users could upgrade while keeping their familiar programs.
DEC VAX computers used a CISC design, as we mentioned. Its assembly language was user-friendly. The instruction set was powerful and orthogonal, which in turn, made it popular among programmers.
DEC VAX computers were among the first system architectures to implement virtual memory. It divided the virtual memory into four 1 GB sections. This design allowed efficient multitasking and memory use.
VAX computer systems rivaled mainframes at a fraction of the cost. They could address over 4 GB of virtual memory. This capacity far exceeded most minicomputers of the time.
Due to their advanced networking features, VAX systems are ideal for multi-user environments. DECnet is a significant proprietary networking protocol that allows VAX
processors to connect with other systems, creating an interconnected computing ecosystem.
This instructional design enabled programming flexibility, ensuring the smooth development of complex applications.
There were over 100 DEC VAX models spanning ten designs. All were compatible with each other. Most of them ran on the VAX/VMS operating system. This variety gave users flexibility in choosing systems.
Several VAX processors support multiprocessing, enabling multiple CPUs to work together seamlessly to enhance performance.
DEC VAX computers were known for their dependability. They had lower operating and maintenance costs. This made them attractive to businesses and institutions.
Due to its exceptional hardware flexibility, DEC VAX supports a wide range of peripheral devices, including various networking components, storage options, and I/O devices.
VAX computer systems played a crucial role in PC software development. They provided a robust platform for UNIX and C software. VAX computers offered higher throughput than PDP-11/70 for UNIX operations.
The powerful VAX/VMS operating system supports the DEC VAX series, which offers a reliable, stable, and secure computing environment.
The VAX/VMS OS (VAX Virtual Memory System) is a multiprocessing, multiuser, and virtual memory-based operating system. It was developed to support time-sharing operations, batch processing, and transaction processing. It is perfect for running workstation applications.
VAX/VMS is a highly secure and reliable operating system that was developed by Digital in 1977 to run on the DEC VAX. After Alpha AXP came out, it was called OpenVMS and ported to the new hardware instead of creating a new OS.
One thing to note is how it helps DEC VAX in managing virtual memory. VAX/VMS takes both hardware and software support to map virtual addresses, creating the illusion of more memory for implemented programs.
VAX/VMS OS has several features that make it unique and useful for DEC VAX users. These include the following:
Virtual Memory Management: VAX/VMS extends the use of available memory by utilizing disk space as additional memory to manage large workloads efficiently.
Multitasking: It enables the OS to run multiple processes simultaneously without hindering each other.
Clustering: This allows a wide range of separate computers to stay interconnected as a single system, enhancing data recovery abilities and accessibility during failure.
Process Isolation: Each process has its own space to prevent interference from others running simultaneously, which offers the stability and security ideal for mission-critical operations.
Security: The VAX/VMS OS uses advanced access control, privilege management, and auditing, including in multi-user settings, to maintain security on every level.
Despite VAX servers having crossed the EOL date years ago, many enterprises still maintain their DEC VAX hardware with VAX/VMS operating system. They face expensive and difficult maintenance, downtime, server failure, security vulnerabilities, lack of DR or sustainability, and what not.
However, a full-scale migration will be difficult for any company driving business-critical operations. They need a timesaving and budget-friendly option; they need Stromasys. We have Charon-VAX that solves all their problems.
The underlying DEC VAX hardware will be replaced with an on-premises or cloud platform while the VAX/VMS operating system and your applications keep running seamlessly. No risky migration process. No coding required.
Our forte lies in a simple lift-and-shift emulation. Enjoy the benefits of a reliable and efficient hardware infrastructure by paying a fraction of the cost of maintaining the age-old hardware.
Although WorkflowOne acquired Relizon Company in 2005, they needed to restructure the company and expand its operations. However, the existing VAX server systems consumed a huge amount of power and took up a lot of space.
They wanted to reduce maintenance costs while increasing the speed and performance of their hardware. However, WorkflowOne wanted to stay away from complete modernization as it would require an immense amount of money, labor, and retraining.
After the help of Quayle Consulting and a proof-of-concept, WorkflowOne went with Charon-VAX. Not only did they save power, space, and maintenance and cooling costs, with better performance and speed as expected, but the company also bought a second Charon-VAX license for disaster recovery.
As Mark Gillespie, the data center operations manager at WorkflowOne, expressed, “We went from paying more than $100,000 in maintenance fees per year to paying just under $10,000 per year. And it took virtually no effort on our part.”
Want more details? Read the whole case study here.
Want to transform your old VAX systems without affecting your VAX/VMS or applications?
Both DEC VAX computers and the VAX/VMS operating system were highly useful for several industries. Government bodies, scientific research, financial services, educational institutions, telecom companies, the manufacturing sector, and enterprises all use these systems for business-critical tasks.
However, currently, VAX hardware running on the VAX/VMS OS is outdated and presents various challenges. Yet, companies using these systems do not want the usual modernization route.
For them, emulation is the best path to ensure that their business on VAX/VMS continues without any hitches, even after their VAX hardware is changed. They can now take their time to transform their technology systems without any hassle.
VAX computer systems excelled in scientific research, engineering, and business applications. VAX/VMS, the operating system, offered advanced features for its time. These included virtual memory, file sharing, and networking. Such capabilities made VAX popular across various industries.
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