Alpha

The DEC Alpha architecture is a 64-bit RISC (Reduced Instruction Set Computing) processor design developed by Digital Equipment Corporation in the early 1990s. It was created with a focus on high performance, scalability, and longevity, intended to support multiple operating systems like OpenVMS, UNIX, and Windows NT.

Alpha employs a pure 64-bit load/store architecture, meaning operations are only performed on registers, and memory is accessed solely through explicit load and store instructions. This design simplifies instruction execution and enhances pipelining efficiency. Instructions are fixed at 32 bits in length, and the architecture avoids the use of condition codes or flag registers, streamlining execution paths and reducing complexity.

To maximize speed, Alpha incorporates superscalar capabilities, allowing multiple instructions to be executed per clock cycle, along with deep instruction pipelines and aggressive branch prediction techniques. It includes robust support for IEEE 754 floating-point operations, making it suitable for scientific and technical workloads.

A distinguishing characteristic of Alpha is its clean, orthogonal instruction set, which reflects a philosophy of simplicity and speed. It was forward-looking, supporting large address spaces and designed to scale into future generations of processors. Despite its strengths, the Alpha architecture was eventually phased out after DEC's acquisition, with its development discontinued in favor of the Itanium platform under Compaq and later HP.

Alpha was the second platform supported by T2's ROCK Linux early days.