ArticlesDEC Alpha was a key microprocessor developed by Digital Equipment Corporation to replace the obsolete VAX architecture.
However, over time, it has transitioned into legacy status and with that many organizations ponder some critical questions: should they continue to rely on this AlphaServers, or is it time to embrace modern architectures like x86? What are the differences between modern architectures such as x86 and DEC Alpha processors?
In this article, you will gain a deeper understanding of DEC Alpha processors and explore the differences between these architectures. By the end of this article, you will have an insider’s perspective that will empower you to make an informed decision for your organization.
DEC Alpha was a microprocessor created by Digital Equipment Corporations (DEC) using the original name of Alpha AXP with the intention of replacing the 32-bit, complex CISC-based VAX architecture.
Therefore, it was based on the principle of 64-bit Reduced Instruction Set Computer (RISC) architecture developed after the initial wave of RISC designs.
While Alpha was mostly a fresh design, it had retained some unusual floating-point rounding modes to ensure compatibility with VAX. Because of these similarities, emulating VAX systems using Alpha was easier.
Alpha arrived as a simple 64-bit RISC architecture. It had fixed-length instructions, 32 integer registers, and could address virtual memory with 43-bit addresses to facilitate later expansion. It was designed to be simpler, enabling pipelining. Five types of instruction were defined: integer, floating-point, branch and compare, load and store, and PALcode instructions.
Alpha computers used PCI architecture, moving away from the older QBUS systems. DEC Alpha processors were common in the 1990s and powered workstations and servers like the DEC 3000 AXP, AlphaStation, and AlphaServer.
Operating systems that ran on the DEC Alpha processors were OpenVMS, Tru64 UNIX (formerly DEC OSF/1 AXP and Digital UNIX), and Windows NT. Interestingly, Windows NT ran natively on Alpha systems and supported x86 applications via binary translation.
Tru64 UNIX was a 64-bit operating system initially developed by DEC and later acquired by Hewlett-Packard (HP).
Compaq acquired Alpha architecture in 1998. As Compaq was already using Intel’s x86 systems, they decided to replace Alpha and jumped on board the next big thing: Hewlett-Packard/Intel Itanium architecture. By 2001, Compaq had sold all Alpha-related intellectual property to Intel and marked the end of the Alpha product line.
Here are few unique characteristics that helped alpha Processors to be quite popular back in their era:
64-bit architecture: Alpha processors brought 64-bit support early on, featuring 64-bit ALUs, registers, and pointers
High clock rates: Its RISC-based design, with simplified registers and fixed instruction sizes, allowed Alpha to hit clock speeds of 192MHz as early as 1992
Superscalar processing: The CPUs also supported superscalar processing, with the ability to handle multiple instructions at once.
Multiprocessor support: Alpha included built-in multiprocessor support but had a weaker memory model.
On-chip secondary cache: Starting with the Alpha 21164, secondary cache was built in
Out-of-order execution: It’s a technique of utilizing the circles that would otherwise be wasted. Alpha’s 21264 was one of the first to perform out-of-order execution at high clock speeds, which made the processes faster.
Integrated memory controller: Alpha had this starting with its 21006 and 21364 models.
The DEC Alpha and x86 architectures represent two distinct approaches to microprocessor design, each with its own strengths and weaknesses. Below is a detailed comparison based on various technical aspects.
| DEC Alpha | x86 | |
|---|---|---|
| Type | 64-bit RISC | CISC |
| Design Focus | Simplicity and performance. It uses pipelining and superscalar execution. | Broader range of instructions that allows completion of more tasks with fewer instructions but adds decoding complexity. |
2. Performance
| DEC Alpha | x86 | |
|---|---|---|
| Overview | High performance, especially in floating-point calculations and large data workloads. | Evolved with features like pipelining and superscalar execution (e.g., Pentium). This helped it to compete in general-purpose and high-performance computing. |
| DEC Alpha | x86 | |
|---|---|---|
| Type | Fixed-length instruction set, simplifying decoding and speeding up pipelining. It lacks some complex instructions, like integer division. | Variable-length instruction set, providing flexibility but complicating decoding. It supports a wide range of legacy software for general-purpose applications. |
| DEC Alpha | x86 | |
|---|---|---|
| Overview | Struggled after Compaq’s acquisition of DEC in 1998, as focus shifted to Intel’s Itanium. The design innovations continue to influence future architectures despite being out of production. | Remains the dominant architecture in personal computers and servers with strong software support and ongoing improvements from Intel and AMD ensure its relevance across various industries. |
Although DEC Alpha was competitive architecture in its time, with time DEC Alpha Hardware reached end-of-life. Consequently, the hardware has become a continuous threat for enterprises. This is where X86 emerged as a reliable and efficient alternative.
Let’s explore why modern organizations are migrating from DEC Alpha to x86:
DEC stopped making AlphaServers in the late 1990s and early 2000s, which means no new hardware is available.
With production halted, new and refurbished parts are becoming scarce. Companies may face long wait times or high prices when sourcing from third-party vendors.
The mission-critical legacy application is dependent on the legacy hardware which causes frequent downtime, leading to business disruptions, production loss, and poor customer experience. In fact, the recovery from hardware failure can be prolonged, especially when there is a lack of support and replacement parts.
Starting from downtime, power consumption bills, spare parts, storage space to seeking help from experts, the cost of maintaining DEC alpha processors are constantly rising and limiting the business’s ability to spend on other important projects.
DEC Alpha processor was cutting-edge in its day but is nowhere as fast or efficient compared to modern counterparts. This can cause processing speed degradation and an application throughputs decrease.
With an aging workforce, the number of IT professionals versed in DEC Alpha systems continues to shrink. This leads to difficulty in locating well-trained and knowledgeable personnel for maintenance and repairs.
If you oversee the IT department in a company relying on DEC Alpha processors, Stromasys could be an excellent option.
Charon-AXP by Stromasys is an Alpha emulator which creates a virtual Alpha environment on an industry-standard x86 platform. This lets you keep running your original OpenVMS and Tru64 Unix applications without any modifications.
This project does not involve any risky migration. There is no need to write any code. In fact, your end user will not even notice that the DEC Alpha hardware has been replaced with a modern x86-based infrastructure. This offers the best of both worlds: you can keep your critical and familiar applications working while enjoying the efficiency of a new hardware platform.
Wish to replace the outdated AlphaServers?
1. Why did DEC Alpha fail?
After acquiring DEC, Compaq decided to phase out the Alpha architecture and ultimately selected the Itanium architecture developed in partnership with Hewlett-Packard and Intel. Again, a changing competitive environment and the evolving x86 architectural landscape with updated instruction sets and support for modern software applications further fueled businesses’ interest in x86.
2. Is the alpha processor still used?
Though it is not produced or actively sold by any companies, Alpha processors can still be found in organizations using legacy systems for running their business applications.
3. What is Alpha in computers?
Alpha, launched as the Alpha AXP, is a 64-bit RISC instruction set architecture (ISA) developed by DEC. It was introduced as a processor to replace the 32-bit VAX complicated instruction set computers (CISC) and be an aggressive RISC processor for Unix workstations and similar markets.
The Challenge: Aging Hardware Limits M&A Activities Businesses are managing more data and IT systems...
Read More
Many businesses still rely on legacy systems. This may be due to an investment in...
Read More
Despite their age and obsolescence, many organizations still cling to SPARC systems for their operations....
Read More