DEC Alpha

Alpha

"Alpha Generation" logo used by Digital
Designer	Digital Equipment Corporation
Bits	64-bit
Introduced	1992; 32 years ago (1992)
Design	RISC
Type	Register-Register
Encoding	Fixed
Endianness	Bi
Extensions	Byte/Word Extension (BWX), Square-root and Floating-point Convert Extension (FIX), Count Extension (CIX), Motion Video Instructions (MVI)
Open	Yes[1]
Registers
General-purpose	31 plus always-zero R31
Floating point	31 plus always-0.0 F31

Alpha microprocessors

DEC AXP 21064 die photo

DEC AXP 21064 package

DEC AXP 21064 bare die mounted on business card with some statistics

Compaq 21264C

Alpha (original name Alpha AXP) is a 64-bit reduced instruction set computer (RISC) instruction set architecture (ISA) developed by Digital Equipment Corporation (DEC). Alpha was designed to replace 32-bit VAX complex instruction set computers (CISC) and to be a highly competitive RISC processor for Unix workstations and similar markets.

Alpha is implemented in a series of microprocessors originally developed and fabricated by DEC. These microprocessors are most prominently used in a variety of DEC workstations and servers, which eventually formed the basis for almost all of their mid-to-upper-scale lineup. Several third-party vendors also produced Alpha systems, including PC form factor motherboards.

Operating systems that support Alpha included OpenVMS (formerly named OpenVMS AXP), Tru64 UNIX (formerly named DEC OSF/1 AXP and Digital UNIX), Windows NT (discontinued after NT 4.0; and prerelease Windows 2000 RC2),^[2] Linux (Debian, SUSE,^[3] Gentoo and Red Hat), BSD UNIX (NetBSD, OpenBSD and FreeBSD up to 6.x), Plan 9 from Bell Labs, and the L4Ka::Pistachio kernel. A port of Ultrix to Alpha was carried out during the initial development of the Alpha architecture, but was never released as a product.^[4]

The Alpha architecture was sold, along with most parts of DEC, to Compaq in 1998.^[5] Compaq, already an Intel x86 customer, announced that they would phase out Alpha in favor of the forthcoming Hewlett-Packard/Intel Itanium architecture, and sold all Alpha intellectual property to Intel, in 2001,^[6] effectively killing the product. Hewlett-Packard purchased Compaq in 2002, continuing development of the existing product line until 2004, and selling Alpha-based systems, largely to the existing customer base, until April 2007.^[7]