DEC Alpha

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Designer Digital Equipment Corporation
Bits 64-bit
Introduced 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]
General purpose 32 (R31 is always 0)
Floating point 32 (F31 is always 0.0)
DEC Alpha AXP 21064 Microprocessor die photo
Package for DEC Alpha AXP 21064 Microprocessor
Alpha AXP 21064 bare die mounted on a business card with some statistics
Compaq Alpha 21264C.
An early multi chip module prototype of the Alpha subdivided

Alpha, originally known as Alpha AXP, is a 64-bit reduced instruction set computing (RISC) instruction set developed by Digital Equipment Corporation (DEC), designed to replace their 32-bit VAX complex instruction set computer (CISC) instruction set. Alpha was implemented in microprocessors originally developed and fabricated by DEC. These microprocessors were 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 supported Alpha included OpenVMS (previously known as OpenVMS AXP), Tru64 UNIX (previously known as DEC OSF/1 AXP and Digital UNIX), Windows NT (using a 32-bit emulation layer and discontinued after 4.0 SP6 and Windows 2000 RC1),[2] GNU/Linux (Debian GNU/Linux, SUSE Linux,[3] Gentoo Linux and Red Hat Linux), BSD UNIX (NetBSD, OpenBSD and FreeBSD up to 6.x), as well as the L4Ka::Pistachio kernel.




Alpha was born out of an earlier RISC project named PRISM, itself the final product of several earlier projects. PRISM was intended to be a flexible design, supporting both Unix-like applications, as well as Digital's existing VMS programs from the VAX after minor conversion. A new Unix-like[citation needed] operating system known as Mica would run applications natively, supporting VMS under emulation running at the same time.

During development, the Palo Alto design team were working on a Unix-only workstation that originally included the PRISM. However, development of the workstation was well ahead of the PRISM, and the engineers proposed that they release the machines using the MIPS R2000 processor instead, moving its release date up considerably. DEC management doubted the need to produce a new computer architecture to replace their existing VAX and DECstation lines, and eventually ended the PRISM project in 1988.



Another study was started to see if a new RISC architecture could be defined that could directly support the VMS operating system. The new design used most of the basic PRISM concepts, but was re-tuned to allow VMS and VMS programs to run at reasonable speed with no conversion at all. The decision was also made to upgrade the design to a full 64-bit implementation from PRISM's 32-bit, a conversion all of the major RISC vendors were undertaking. Eventually that new architecture became Alpha. The primary Alpha instruction set architects were Richard L. Sites and Richard T. Witek. The PRISM's Epicode was developed into the Alpha's PALcode, providing an abstracted interface to platform- and processor implementation-specific features.

The main contribution of Alpha to the microprocessor industry, and the main reason for its performance, was not so much the architecture but rather its implementation.[citation needed] At that time (as it is now), the microchip industry was dominated by automated design and layout tools. The chip designers at Digital continued pursuing sophisticated manual circuit design in order to deal with the overly complex VAX architecture. The Alpha chips showed that manual circuit design applied to a simpler, cleaner architecture allowed for much higher operating frequencies than those that were possible with the more automated design systems. These chips caused a renaissance of custom circuit design within the microprocessor design community.

Originally, the Alpha processors were designated the DECchip 21x64 series, with "DECchip" replaced in the mid-1990s with "Alpha". The first two digits, "21" signifies the 21st century, and the last two digits, "64" signifies 64 bits. The Alpha was designed as 64-bit from the start and there is no 32-bit version. The middle digit corresponded to the generation of the Alpha architecture. Internally, Alpha processors were also identified by EV numbers, EV officially standing for "Extended VAX" but having an alternative humorous meaning of "Electric Vlasic", giving homage to the Electric Pickle experiment at Western Research Lab.[5]

Improved models[edit]

The first few generations of the Alpha chips were some of the most innovative of their time. The first version, the Alpha 21064 or EV4, was the first CMOS microprocessor whose operating frequency rivalled higher-powered ECL minicomputers and mainframes. The second, 21164 or EV5, was the first microprocessor to place a large secondary cache on chip. The third, 21264 or EV6, was the first microprocessor to combine both high operating frequency and the more complicated out-of-order execution microarchitecture. The 21364 or EV7 was the first high performance processor to have an on-chip memory controller. The unproduced 21464 or EV8 would have been the first to include simultaneous multithreading, but this version was canceled after the sale of DEC to Compaq. The Tarantula research project, which most likely would have been called EV9, would have been the first Alpha processor to feature a vector unit.[6]

A persistent report attributed to DEC insiders suggests the choice of the AXP tag for the processor was made by DEC's legal department, which was still smarting from the VAX trademark fiasco.[citation needed] After a lengthy search the tag "AXP" was found to be entirely unencumbered. Within the computer industry, a joke got started that the acronym AXP meant "Almost eXactly PRISM".

Design principles[edit]

The Alpha architecture was intended to be a high-performance design. Digital intended the architecture to support a one-thousandfold increase in performance over twenty-five years. To ensure this, any architectural feature that impeded multiple instruction issue, clock rate or multiprocessing was removed. As a result, the Alpha does not have:

  • Branch delay slots
  • Suppressed instructions
  • Byte load or store instructions (later added with the Byte Word Extensions (BWX))

Condition codes[edit]

The Alpha does not have condition codes for integer instructions to remove a potential bottleneck at the condition status register. Instructions resulting in an overflow, such as adding two numbers whose result does not fit in 64 bits, write the 32 or 64 least significant bits to the destination register. The carry is generated by performing an unsigned compare on the result with either operand to see if the result is smaller than either operand. If the test was true, the value one is written to the least significant bit of the destination register to indicate the condition.


DEC Alpha registers
63 . . . 47 . . . 31 . . . 15 . . . 01 00 (bit position)
General-purpose registers
R0 R0
R1 R1
R2 R2
R29 R29
R30 R30
 R31 (zero) R31, always zero
Floating-point registers
F0 F0
F1 F1
F2 F2
F29 F29
F30 F30
 F31 (zero) F31, always zero
Program counter
 PC 0 0 Program Counter
Control registers
LR0 Lock Register 0
LR1 Lock Register 1
FPCR FP Control Register

The architecture defined a set of 32 integer registers and a set of 32 floating-point registers in addition to a program counter, two lock registers and a floating-point control register (FPCR). It also defined registers that were optional, implemented only if the implementation required them. Lastly, registers for PALcode were defined.

The integer registers were denoted by R0 to R31 and floating-point registers were denoted by F0 to F31. The R31 and F31 registers were hardwired to zero and writes to those registers by instructions are ignored. Digital considered using a combined register file, but a split register file was determined to be better as it enabled two-chip implementations to have a register file located on each chip and integer-only implementations to omit the floating-point register file containing the floating point registers. A split register file was also determined to be more suitable for multiple instruction issue due to the reduced number of read and write ports. The number of registers per register file was also considered, with 32 and 64 being contenders. Digital concluded that 32 registers was more suitable as it required less die space, which improved clock frequencies. This number of registers was deemed not to be a major issue in respect to performance and future growth, as thirty-two registers could support at least eight-way instruction issue.

The program counter is a 64-bit register which contains a longword-aligned virtual byte address, that is, the low two bits of the program counter are always zero. The PC is incremented by four to the address of the next instruction when an instruction is decoded. A lock flag and locked physical address register are used by the load-locked and store-conditional instructions for multiprocessor support. The floating-point control register (FPCR) is a 64-bit register defined by the architecture intended for use by Alpha implementations with IEEE 754-compliant floating-point hardware.

Data types[edit]

In the Alpha architecture, a byte was defined as an 8-bit datum, a word as a 16-bit datum, a longword as a 32-bit datum, a quadword as a 64-bit datum and an octaword as a 128-bit datum.

The Alpha architecture originally defined six data types:

  • Quadword (64-bit) integer
  • Longword (32-bit) integer
  • IEEE T-floating-point (double precision, 64-bit)
  • IEEE S-floating-point (single precision, 32-bit)

To maintain a level of compatibility with VAX, the 32-bit architecture the Alpha succeeded, two VAX data types were included:

  • VAX G-floating point (double precision, 64-bit)
  • VAX F-floating point (single precision, 32-bit)

The Alpha had some provision for future expansion of the instruction set to include 128-bit data types.


The Alpha has a 64-bit linear virtual address space with no memory segmentation. Implementations can implement a smaller virtual address space with a minimum size of 43 bits. Although the unused bits were not implemented in hardware such as TLBs, the architecture required implementations to check if they are zero to ensure software compatibility with implementations that implemented a larger or the full virtual address space.

Instruction formats[edit]

Opcode Ra Rb Unused 0 Function Rc Integer operate
Opcode Ra Literal 1 Function Rc Integer operate, literal
Opcode Ra Rb Function Rc Floating-point operate
Opcode Ra Rb Displacement Memory format
Opcode Ra Displacement Branch format
Opcode Function CALL_PAL format

The Alpha ISA has a fixed instruction length of 32 bits. It has six instruction formats.

The integer operate format is used by integer instructions. It contains a 6-bit opcode field, followed by the Ra field, which specifies the register containing the first operand and the Rb field, specifies the register containing the second operand. Next is a 3-bit field which is unused and reserved. A 1-bit field contains a "0", which distinguished this format from the integer literal format. A 7-bit function field follows, which is used in conjunction with the opcode to specify an operation. The last field is the Rc field, which specifies the register which the result of a computation should be written to. The register fields are all 5 bits long, required to address 32 unique locations, the 32 integer registers.

The integer literal format is used by integer instructions which use a literal as one of the operands. The format is the same as the integer operate format except for the replacement of the 5-bit Rb field and the 3 bits of unused space with an 8-bit literal field which is zero-extended to a 64-bit operand.

The floating-point operate format is used by floating-point instructions. It is similar to the integer operate format, but has an 11-bit function field made possible by using the literal and unused bits which are reserved in integer operate format.

The memory format is used mostly by load and store instructions. It has a 6-bit opcode field, a 5-bit Ra field, a 5-bit Rb field and a 16-bit displacement field.

Branch instructions have a 6-bit opcode field, a 5-bit Ra field and a 21-bit displacement field. The Ra field specifies a register to be tested by a conditional branch instruction, and if the condition is met, the program counter is updated by adding the contents of the displacement field with the program counter. The displacement field contains a signed integer and if the value of the integer is positive, if the branch is taken then the program counter is incremented. If the value of the integer is negative, then program counter is decremented if the branch is taken. The range of a branch thus is ±1 Mi instructions, or ±4 MiB. The Alpha Architecture was designed with a large range as part of the architecture's forward-looking goal.

The CALL_PAL format is used by the CALL_PAL instruction, which is used to call PALcode subroutines. The format retains the opcode field but replaces the others with a 26-bit function field, which contains an integer specifying a PAL subroutine.

Instruction set[edit]

Control instructions[edit]

The control instructions consist of conditional and unconditional branches, and jumps. The conditional and unconditional branch instructions use the branch instruction format, while the jump instructions use the memory instruction format.

Conditional branches test the least significant bit of a register is set or clear, or compare a register as a signed quadword to zero, and branch if the specified condition is true. These conditions available for comparing a register to zero are equality, inequality, less than, less than or equal to, greater than or equal to, and greater than. The new address is computed by longword aligning and sign extending the 21-bit displacement and adding it to the address of the instruction following the conditional branch.

Unconditional branches update the program counter with a new address computed in the same way as conditional branches. They also save the address of the instruction following the unconditional branch to a register. There are two such instructions, and they differ only in the hints provided for the branch prediction hardware.

There are four jump instructions. These all perform the same operation, saving the address of the instruction following the jump, and providing the program counter with a new address from a register. They differ in the hints provided to the branch prediction hardware. The unused displacement field is used for this purpose.

Integer arithmetic[edit]

The integer arithmetic instructions perform addition, multiplication, and subtraction on longwords and quadwords; and comparison on quadwords. There is no instruction(s) for division as the architects considered the implementation of division in hardware to be adverse to simplicity. In addition to the standard add and subtract instructions, there are scaled versions. These versions shift the second operand to the left by two or three bits before adding or subtracting. The Multiply Longword and Multiply Quadword instructions write the least significant 32 or 64 bits of a 64- or 128-bit result to the destination register, respectively. Since it is useful to obtain the most significant half, the Unsigned Multiply Quadword High (UMULH) instruction is provided. UMULH is used for implementing multi-precision arithmetic and division algorithms. The concept of a separate instruction for multiplication that returns the most significant half of a result was taken from PRISM.

The instructions that operate on longwords ignore the most significant half of the register and the 32-bit result is sign-extended before it is written to the destination register. By default, the add, multiply, and subtract instructions, with the exception of UMULH and scaled versions of add and subtract, do no trap on overflow. When such functionality is required, versions of these instructions that perform overflow detection and trap on overflow are provided.

The compare instructions compare two registers or a register and a literal and write '1' to the destination register if the specified condition is true or '0' if not. The conditions are equality, inequality, less than or equal to, and less than. With the exception of the instructions that specify the former two conditions, there are versions that perform signed and unsigned compares.

The integer arithmetic instructions use the integer operate instruction formats.

Logical and shift[edit]

The logical instructions consist of those for performing bitwise logical operations and conditional moves on the integer registers. The bitwise logical instructions perform AND, NAND, NOR, OR, XNOR, and XOR between two registers or a register and literal. The conditional move instructions test a register as a signed quadword to zero and move if the specified condition is true. The specified conditions are equality, inequality, less than or equal to, less than, greater than or equal to, and greater than. The shift instructions perform arithmetic right shift, and logical left and right shifts. The shift amount is given by a register or literal. Logical and shift instructions use the integer operate instruction formats.


Byte-Word Extensions (BWX)[edit]

Later, the Alpha included byte-word extensions, a set of instructions to manipulate 8-bit and 16-bit data types. These instructions were first introduced in the 21164A (EV56) microprocessor and are present in all subsequent implementations. These instructions performed operations that previously required multiple instructions to implement, which improved code density and the performance of certain applications. BWX also made the emulation of x86 machine code and the writing of device drivers easier.[7]

Mnemonic Instruction
LDBU Load Zero-Extended Byte from Memory to Register
LDWU Load Zero-Extended Word from Memory to Register
SEXTB Sign Extend Byte
SEXTW Sign Extend Word
STB Store Byte from Register to Memory
STW Store Word from Register to Memory

Motion Video Instructions (MVI)[edit]

Motion Video Instructions (MVI) was an instruction set extension to the Alpha ISA that added instructions for single instruction, multiple data (SIMD) operations.[8] Alpha implementations that implement MVI, in chronological order, are the Alpha 21164PC (PCA56 and PCA57), Alpha 21264 (EV6) and Alpha 21364 (EV7). Unlike other SIMD instruction sets of the same period such as MIPS' MDMX or Sun Microsystems' Visual Instruction Set, MVI was a simple instruction set composed of a few instructions that operate on integer data types stored in existing integer registers.

MVI's simplicity was due to two reasons. Firstly, Digital had determined that the Alpha 21164 was already capable of performing DVD decoding through software, therefore not requiring hardware provisions for the purpose, but was inefficient in MPEG-2 encoding. The second reason was the requirement to retain the fast cycle times of implementations. Adding many instructions would have complicated and enlarged the instruction decode logic, reducing an implementation's clock frequency.

MVI consisted of 13 instructions:

Mnemonic Instruction
MAXSB8 Vector Signed Byte Maximum
MAXSW4 Vector Signed Word Maximum
MAXUB8 Vector Unsigned Byte Maximum
MAXUW4 Vector Unsigned Word Maximum
MINSB8 Vector Signed Byte Minimum
MINSW4 Vector Signed Word Minimum
MINUB8 Vector Unsigned Byte Minimum
MINUW4 Vector Unsigned Word Minimum
PERR Pixel Error
PKLB Pack Longwords to Bytes
PKWB Pack Words to Bytes
UNPKBL Unpack Bytes to Longwords
UNPKBW Unpack Bytes to Words

Floating-point Extensions (FIX)[edit]

Floating-point extensions (FIX) was an extension the Alpha Architecture. It introduced nine instructions for floating-point square-root and for transferring data to and from the integer registers and floating-point registers. The Alpha 21264 (EV6) was the first microprocessor to implement these instructions.

Mnemonic Instruction
FTOIS Floating-point to Integer Register Move, S_floating
FTOIT Floating-point to Integer Register Move, T_floating
ITOFF Integer to Floating-point Register Move, F_floating
ITOFS Integer to Floating-point Register Move, S_floating
ITOFT Integer to Floating-point Register Move, T_floating
SQRTF Square root F_floating
SQRTG Square root G_floating
SQRTS Square root S_floating
SQRTT Square root T_floating

Count Extensions (CIX)[edit]

Count Extensions (CIX) was an extension to the architecture which introduced three instructions for counting bits. These instructions were categorized as integer arithmetic instructions. They were first implemented on the Alpha 21264A (EV67).

Mnemonic Instruction
CTLZ Count Leading Zero
CTPOP Count Population
CTTZ Count Trailing Zero



The Alpha 21164 or EV5 became available in 1995 at processor frequencies of up to 333 MHz. In July 1996 the line was speed bumped to 500 MHz, in March 1998 to 666 MHz. Also in 1998 the Alpha 21264 (EV6) was released at 450 MHz, eventually reaching (in 2001 with the 21264C/EV68CB) 1.25 GHz. In 2003, the Alpha 21364 or EV7 Marvel was launched, essentially an EV68 core with four 1.6 GB/s[9] inter-processor communication links for improved multiprocessor system performance, running at 1 or 1.15 GHz.


On June 25, 2001, Compaq announced that Alpha would be phased out by 2004 in favor of Intel's Itanium, canceled the planned EV8 chip, and sold all Alpha intellectual property to Intel.[10] HP, new owner of Compaq later the same year, announced that development of the Alpha series would continue for a few more years, including the release of a 1.3 GHz EV7 variant called the EV7z. This would be the final iteration of Alpha, the 0.13 µm EV79 also being canceled.

Alpha was also implemented in the Piranha, a research prototype developed by Compaq's Corporate Research and Nonstop Hardware Development groups at the Western Research Laboratory and Systems Research Center. Piranha was a multicore design for transaction processing workloads that contained eight simple cores. It was described at the 27th Annual International Symposium on Computer Architecture in June 2000.[11]

Model history[edit]

Model Model number Year Frequency [MHz] Process [µm] Transistors [millions] Die size [mm2] IO Pins Power [W] Voltage Dcache [KB][12] Icache [KB] Scache Bcache ISA
EV4 21064 1992 100–200 0.75 1.68 234 290 30 3.3 8 8 128 KB–16 MB  
EV4S 21064 1993 100–200 0.675 1.68 186 290 27 3.3 8 8 128 KB–16 MB  
EV45 21064A 1994 200–300 0.5 2.85 164 33 3.3 16 16 256 KB–16 MB  
LCA4 21068 1994 66 0.675 1.75 209 9 3.3 8 8    
LCA45 21066A 1994 100–266 0.5 1.8 161 23 3.3 8 8    
LCA45 21068A 1994 100 0.5 1.8 161 3.3 8 8    
EV5 21164 1995 266–500 0.5 9.3 299 296 56 3.3/2.5 8 8 96 KB Up to 64 MB R
EV56 21164A 1996 366–666[13] 0.35 9.66[13] 209 31–55[13] 3.3/2.5[13] 8 8 96 KB Up to 64 MB R,B
PCA56 21164PC 1997 400–533 0.35 3.5 141 264 26–35 3.3/2.5 8 16 512 KB–4 MB R,B,M
PCA57 21164PC   600–666 0.28 5.7 101 283 18–23 2.5/2.0 16 32[13] 512 KB–4 MB R,B,M
EV67 21264A 1999 600–750 0.25 15.2 210 389   2.0 64 64 2–8 MB R,B,M,F,C
EV7 21364 2003 1000–1150 0.18 130 397 125 1.5 64 64 1.75 MB R,B,M,F,C,T
EV7z 21364 2004 1300 0.18 130 397 125 1.5 64 64 1.75 MB R,B,M,F,C,T
EV78/EV79 21364A Slated for 2004 1700 0.13 152 300 120 1.2 64 64 1.75 MB R,B,M,F,C,T
EV8 21464 Slated for 2003 1200–2000 0.125 250 420 1800 ?? 1.2 64 64 3 MB R,B,M,F,C,T
ISA extensions
  • R – Hardware support for rounding to infinity and negative infinity.[14]
  • M – MVI, "multimedia" instructions
  • C – CIX, instructions for counting and finding bits


To illustrate the comparative performance of Alpha-based systems, some SPEC performance numbers (SPECint95, SPECfp95) are listed below. Note that the SPEC results claim to report the measured performance of a whole computer system (CPU, bus, memory, compiler optimizer), not just the CPU. Also note that the benchmark and scale changed from 1992 to 1995. However, the figures give a rough impression of the performance of the Alpha architecture (64-bit), compared with the contemporary HP (64-bit) and Intel-based offerings (32-bit). Perhaps the most obvious trend is that while Intel could always get reasonably close to Alpha in integer performance, in floating point performance the difference was considerable. On the other side, HP (PA-RISC) is also reasonably close to Alpha, but these CPUs are running at significantly lower clock rates (MHz). The tables lack two important values: the power consumption and the price of a CPU.

Alpha-based systems[edit]


DEC also produced a PC-like Alpha workstation with an EISA bus, the DECpc AXP 150 (codename "Jensen", also known as the DEC 2000 AXP). This was the first Alpha system to support Windows NT. DEC later produced Alpha versions of their Celebris XL and Digital Personal Workstation PC lines, with 21164 processors.






A number of OEM motherboards were produced by DEC, such as the 21066 and 21068-based AXPpci 33 "NoName", which was part of a major push into the OEM market by the company,[15] the 21164-based AlphaPC 164 and AlphaPC 164LX, the 21164PC-based AlphaPC 164SX and AlphaPC 164RX and the 21264-based AlphaPC 264DP. Several third parties such as Samsung and API also produced OEM motherboards such as the API UP1000 and UP2000.




The fastest supercomputers based on Alpha processors:

  • Sunway Blue Light at Chinese National Supercomputing Center in Jinan. Machine: Sunway BlueLight MPP. CPU: 8575 SW1600 (16 Cores/CPU, 21164A EV-56, 975 MHz). Rmax=795.9TFlops, Rpeak=1070.2TFlops.[16]
  • ASCI Q at Los Alamos National Laboratory. Machine: HP AlphaServer SC45/GS Cluster. CPU: 4096 Alpha (21264 EV-68, 1.25 GHz). Rmax: 7.727 Teraflops.[17]


  1. ^ Bolotoff, Paul V. (14 April 2005). "Alpha: The History in Facts and Comments". Alasir. 
  2. ^ Aaron Sakovich (2001). "Windows 2000?". The AlphaNT Source. Retrieved 2007-01-01. 
  3. ^ "SUSE Linux 7.0 Alpha Edition". SUSE. 2000. Retrieved 2014-01-08. 
  4. ^ "Transforming your AlphaServer environment". HP. Retrieved 2007-01-11. 
  5. ^ Bill Hamburgen, Jeff Mogul, Brian Reid, Alan Eustace, Richard Swan, Mary Jo Doherty, Joel Bartlett (1989). "WRL Technical Note TN-13: Characterization of Organic Illumination Systems" (PDF). Digital Equipment Corporation. Retrieved 2007-10-04. 
  6. ^ Espasa, Roger; Federico Ardanaz, Julio Gago, Roger Gramunt, Isaac Hernandez, Toni Juan, Joel Emer, Stephen Felix, Geoff Lowney, Matthew Mattina, Andre Seznec (2002). Danielle C. Martin, ed. "Proceedings: 29th Annual International Symposium on Computer Architecture (ISCA '02)" (PDF). 29th Annual International Symposium on Computer Architecture (ISCA '02). Joe Daigle/Studio Productions. Los Alamitos, Calif: IEEE Computer Society. pp. Page(s): 281–292. doi:10.1109/ISCA.2002.1003586. ISBN 0-7695-1605-X. Retrieved 2007-10-04.  |chapter= ignored (help)
  7. ^ Gronowski, P. E.; Bowhill, W. J.; Donchin, D. R.; Blake-Campos, R. P.; Carlson, D. A.; Equi, E. R.; Loughlin, B. J.; Mehta, S.; Mueller, R. O.; Olesin, A.; Noorlag, D. J. W.; Preston, R. P. (1996). "A 433-MHz 64-b quad-issue RISC microprocessor". IEEE Journal of Solid-State Circuits 31 (11): 1687–1696. doi:10.1109/JSSC.1996.542313.  edit
  8. ^ Gwennap, Linley (18 November 1996). "Digital, MIPS Add Multimedia Extensions". Microprocessor Report.
  9. ^ In the context of data transfer, 1 GB is used to mean 1 billion bytes
  10. ^ Popovich, Ken (2001-06-28). "Alpha proved costly for Compaq". ZDNet. Retrieved 2009-05-01. 
  11. ^ Luiz André Barroso, Kourosh Gharachorloo, Robert McNamara, Andreas Nowatzyk, Shaz Qadeer, Barton Sano, Scott Smith, Robert Stets, and Ben Verghese (2000). "Piranha: A Scalable Architecture Based on Single-Chip Multiprocessing". Proceedings of the 27th Annual International Symposium on Computer Architecture.
  12. ^ In the context of cache memory, 1 KB = 1024 bytes; 1 MB = 1024 KB
  13. ^ a b c d e Paul V. Bolotoff (21 April 2007). "Alpha: The History in Facts and Comments". Retrieved Nov 22, 2008. 
  14. ^ David Mosberger. "Overview of Alpha Family". Retrieved Dec 9, 2009. 
  15. ^ Reinhardt Krause. "DEC launching Alpha board push". Electronic News, April 4, 1994.
  16. ^ TOP500 (2011). "Sunway Blue Light - Sunway BlueLight MPP, ShenWei processor SW1600 975.00 MHz, Infiniband QDR". Retrieved 2012-09-15. 
  17. ^ Los Alamos National Laboratories (2002). "The ASCI Q System: 30 TeraOPS Capability at Los Alamos National Laboratory". Retrieved 2010-06-06. 

External links[edit]