64-bit is a word size that defines certain classes of computer architecture, buses, memory and CPUs, and by extension the software that runs on them. 64-bit CPUs have existed in supercomputers since the 1970s (Cray-1
Cray-1
The Cray-1 was a supercomputer designed, manufactured, and marketed by Cray Research. The first Cray-1 system was installed at Los Alamos National Laboratory in 1976, and it went on to become one of the best known and most successful supercomputers in history...
In the context of client-server architecture, a server is a computer program running to serve the requests of other programs, the "clients". Thus, the "server" performs some computational task on behalf of "clients"...
s since the early 1990s. In 2003 they were introduced to the (previously 32-bit
32-bit
The range of integer values that can be stored in 32 bits is 0 through 4,294,967,295. Hence, a processor with 32-bit memory addresses can directly access 4 GB of byte-addressable memory....
A personal computer is any general-purpose computer whose size, capabilities, and original sales price make it useful for individuals, and which is intended to be operated directly by an end-user with no intervening computer operator...
x86-64 is an extension of the x86 instruction set. It supports vastly larger virtual and physical address spaces than are possible on x86, thereby allowing programmers to conveniently work with much larger data sets. x86-64 also provides 64-bit general purpose registers and numerous other...
PowerPC is a RISC architecture created by the 1991 Apple–IBM–Motorola alliance, known as AIM...
processor architectures.
A 64-bit register can store 264 = 18 446 744 073 709 551 616 different values.
Without further qualification, a 64-bit computer architecture generally has integer and addressing registers
Processor register
In computer architecture, a processor register is a small amount of storage available as part of a CPU or other digital processor. Such registers are addressed by mechanisms other than main memory and can be accessed more quickly...
that are 64 bits wide, allowing direct support for 64-bit data types and addresses. However, a CPU might have external data buses or address bus
Address bus
An address bus is a computer bus that is used to specify a physical address. When a processor or DMA-enabled device needs to read or write to a memory location, it specifies that memory location on the address bus...
es with different sizes from the registers, even larger (the 32-bit Pentium had a 64-bit data bus, for instance). The term may also refer to the size of low-level data types, such as 64-bit floating-point
Floating point
In computing, floating point describes a method of representing real numbers in a way that can support a wide range of values. Numbers are, in general, represented approximately to a fixed number of significant digits and scaled using an exponent. The base for the scaling is normally 2, 10 or 16...
numbers.
Architectural implications
Processor registers are typically divided into several groups: integer, floating-point, SIMD
SIMD
Single instruction, multiple data , is a class of parallel computers in Flynn's taxonomy. It describes computers with multiple processing elements that perform the same operation on multiple data simultaneously...
, control, and often special registers for address arithmetic which may have various uses and names such as address, index or base registers. However, in modern designs, these functions are often performed by more general purpose integer registers. In most processors, only integer and/or address-registers can be used to address data in memory, the other types cannot. The size of these registers therefore normally limits the amount of directly addressable memory, even if there are registers, such as floating-point registers, that are wider.
Most high performance 32-bit and 64-bit processors (some notable exceptions are most ARM
ARM architecture
ARM is a 32-bit reduced instruction set computer instruction set architecture developed by ARM Holdings. It was named the Advanced RISC Machine, and before that, the Acorn RISC Machine. The ARM architecture is the most widely used 32-bit ISA in numbers produced...
MIPS is a reduced instruction set computer instruction set architecture developed by MIPS Technologies . The early MIPS architectures were 32-bit, and later versions were 64-bit...
CPUs) have integrated floating point hardware, which is often, but not always, based on 64-bit units of data. For example, although the x86/x87
X87
x87 is a floating point-related subset of the x86 architecture instruction set. It originated as an extension of the 8086 instruction set in the form of optional floating point coprocessors that worked in tandem with corresponding x86 CPUs. These microchips had names ending in "87"...
architecture has instructions capable of loading and storing 64-bit (and 32-bit) floating-point values in memory, the internal data and register format is 80 bits wide. In contrast, the 64-bit Alpha
DEC Alpha
Alpha, originally known as Alpha AXP, is a 64-bit reduced instruction set computer instruction set architecture developed by Digital Equipment Corporation , designed to replace the 32-bit VAX complex instruction set computer ISA and its implementations. Alpha was implemented in microprocessors...
family uses a 64-bit floating-point data and register format (as well as 64-bit integer registers).
History
Most CPUs are designed so that the contents of a single integer register can store the address
Memory address
A digital computer's memory, more specifically main memory, consists of many memory locations, each having a memory address, a number, analogous to a street address, at which computer programs store and retrieve, machine code or data. Most application programs do not directly read and write to...
(location) of any datum in the computer's virtual memory
Virtual memory
In computing, virtual memory is a memory management technique developed for multitasking kernels. This technique virtualizes a computer architecture's various forms of computer data storage , allowing a program to be designed as though there is only one kind of memory, "virtual" memory, which...
. Therefore, the total number of addresses in the virtual memory — the total amount of data the computer can keep in its working area — is determined by the width of these registers. Beginning in the 1960s with the IBM
IBM
International Business Machines Corporation or IBM is an American multinational technology and consulting corporation headquartered in Armonk, New York, United States. IBM manufactures and sells computer hardware and software, and it offers infrastructure, hosting and consulting services in areas...
The IBM System/360 was a mainframe computer system family first announced by IBM on April 7, 1964, and sold between 1964 and 1978. It was the first family of computers designed to cover the complete range of applications, from small to large, both commercial and scientific...
(which was an exception, in that it used the low order 24 bits of a word for addresses, resulting in a 16 MB
Megabyte
The megabyte is a multiple of the unit byte for digital information storage or transmission with two different values depending on context: bytes generally for computer memory; and one million bytes generally for computer storage. The IEEE Standards Board has decided that "Mega will mean 1 000...
[] address space size), then (amongst many others) the DEC
Digital Equipment Corporation
Digital Equipment Corporation was a major American company in the computer industry and a leading vendor of computer systems, software and peripherals from the 1960s to the 1990s...
VAX was an instruction set architecture developed by Digital Equipment Corporation in the mid-1970s. A 32-bit complex instruction set computer ISA, it was designed to extend or replace DEC's various Programmed Data Processor ISAs...
minicomputer in the 1970s, and then with the Intel 80386
Intel 80386
The Intel 80386, also known as the i386, or just 386, was a 32-bit microprocessor introduced by Intel in 1985. The first versions had 275,000 transistors and were used as the central processing unit of many workstations and high-end personal computers of the time...
in the mid-1980s, a de facto consensus developed that 32 bits was a convenient register size. A 32-bit address register meant that 232 addresses, or 4 GB
Gigabyte
The gigabyte is a multiple of the unit byte for digital information storage. The prefix giga means 109 in the International System of Units , therefore 1 gigabyte is...
of RAM, could be referenced. At the time these architectures were devised, 4 GB of memory was so far beyond the typical quantities (4 MB) in installations that this was considered to be enough "headroom" for addressing. 4.29 billion addresses were considered an appropriate size to work with for another important reason: 4.29 billion integers are enough to assign unique references to most entities in applications like database
Database
A database is an organized collection of data for one or more purposes, usually in digital form. The data are typically organized to model relevant aspects of reality , in a way that supports processes requiring this information...
A supercomputer is a computer at the frontline of current processing capacity, particularly speed of calculation.Supercomputers are used for highly calculation-intensive tasks such as problems including quantum physics, weather forecasting, climate research, molecular modeling A supercomputer is a...
architectures of the 1970s and 1980s used registers up to 64 bits wide. In the mid-1980s, Intel i860 development began culminating in a (too late for Windows NT) 1989 release. However, 32 bits remained the norm until the early 1990s, when the continual reductions in the cost of memory led to installations with quantities of RAM approaching 4 GB, and the use of virtual memory spaces exceeding the 4 GB ceiling became desirable for handling certain types of problems. In response, MIPS and DEC developed 64-bit microprocessor architectures, initially for high-end workstation
Workstation
A workstation is a high-end microcomputer designed for technical or scientific applications. Intended primarily to be used by one person at a time, they are commonly connected to a local area network and run multi-user operating systems...
In the context of client-server architecture, a server is a computer program running to serve the requests of other programs, the "clients". Thus, the "server" performs some computational task on behalf of "clients"...
HAL Computer Systems, Inc was a Campbell, California-based computer manufacturer founded in 1990 by Andrew Heller, a principal designer of the original IBM POWER architecture...
Sun Microsystems, Inc. was a company that sold :computers, computer components, :computer software, and :information technology services. Sun was founded on February 24, 1982...
International Business Machines Corporation or IBM is an American multinational technology and consulting corporation headquartered in Armonk, New York, United States. IBM manufactures and sells computer hardware and software, and it offers infrastructure, hosting and consulting services in areas...
Silicon Graphics, Inc. was a manufacturer of high-performance computing solutions, including computer hardware and software, founded in 1981 by Jim Clark...
, and Hewlett Packard had developed 64-bit architectures for their workstation and server systems. A notable exception to this trend were mainframes
Mainframe computer
Mainframes are powerful computers used primarily by corporate and governmental organizations for critical applications, bulk data processing such as census, industry and consumer statistics, enterprise resource planning, and financial transaction processing.The term originally referred to the...
from IBM, which then used 32-bit data and 31-bit address sizes; the IBM mainframes did not include 64-bit processors until 2000. During the 1990s, several low-cost 64-bit microprocessors were used in consumer electronics and embedded applications. Notably, the Nintendo 64
Nintendo 64
The , often referred to as N64, was Nintendo′s third home video game console for the international market. Named for its 64-bit CPU, it was released in June 1996 in Japan, September 1996 in North America, March 1997 in Europe and Australia, September 1997 in France and December 1997 in Brazil...
The PlayStation 2 is a sixth-generation video game console manufactured by Sony as part of the PlayStation series. Its development was announced in March 1999 and it was first released on March 4, 2000, in Japan...
had 64-bit microprocessors before their introduction in personal computers. High-end printers and network equipment, as well as industrial computers also used 64-bit microprocessors such as the Quantum Effect Devices
Quantum Effect Devices
Quantum Effect Devices was a company originally named Quantum Effect Design, incorporated in 1991. The three founders, Tom Riordan, Earl Killian and Ray Kunita, were senior managers at MIPS Computer Systems Inc....
The R5000 is a microprocessor that implements the MIPS IV instruction set architecture developed by Quantum Effect Design . The project was funded by MIPS Technologies, Inc , also the licensor. MTI then licensed the design to Integrated Device Technology , NEC, NKK, and Toshiba...
. 64-bit computing started to drift down to the personal computer desktop from 2003 onwards, when some models in Apple's Macintosh lines switched to PowerPC 970
PowerPC 970
The PowerPC 970, PowerPC 970FX, PowerPC 970GX, and PowerPC 970MP, are 64-bit Power Architecture processors from IBM introduced in 2002. When used in Apple Inc. machines, they were dubbed the PowerPC G5....
processors (termed "G5" by Apple) and the launch of AMD
Advanced Micro Devices
Advanced Micro Devices, Inc. or AMD is an American multinational semiconductor company based in Sunnyvale, California, that develops computer processors and related technologies for commercial and consumer markets...
x86-64 is an extension of the x86 instruction set. It supports vastly larger virtual and physical address spaces than are possible on x86, thereby allowing programmers to conveniently work with much larger data sets. x86-64 also provides 64-bit general purpose registers and numerous other...
extension to the x86 architecture, itself a response to Intel's Itanium
Itanium
Itanium is a family of 64-bit Intel microprocessors that implement the Intel Itanium architecture . Intel markets the processors for enterprise servers and high-performance computing systems...
An operating system is a set of programs that manage computer hardware resources and provide common services for application software. The operating system is the most important type of system software in a computer system...
s support.
Limitations
Most 64-bit microprocessors on the market today have a physical limit on the amount of memory they can address, considerably lower than the 64-bit limit which would suggest a memory size of 16 exabyte
Exabyte
The exabyte is a unit of information or computer storage equal to one quintillion bytes . The unit symbol for the exabyte is EB...
x86-64 is an extension of the x86 instruction set. It supports vastly larger virtual and physical address spaces than are possible on x86, thereby allowing programmers to conveniently work with much larger data sets. x86-64 also provides 64-bit general purpose registers and numerous other...
currently has a 52 bit limit on physical memory and supports a 48-bit virtual address space. This is 4 PB
Petabyte
A petabyte is a unit of information equal to one quadrillion bytes, or 1000 terabytes. The unit symbol for the petabyte is PB...
The terabyte is a multiple of the unit byte for digital information. The prefix tera means 1012 in the International System of Units , and therefore 1 terabyte is , or 1 trillion bytes, or 1000 gigabytes. 1 terabyte in binary prefixes is 0.9095 tebibytes, or 931.32 gibibytes...
, respectively. A PC cannot contain 4 petabytes of memory (due to the size of current memory chips if nothing else) but AMD envisioned large servers, shared memory clusters, and other uses of physical address space that might approach this in the foreseeable future, and the 52 bit physical address provides ample room for expansion while not incurring the cost of implementing 64-bit physical addresses. Similarly, the 48-bit virtual address space was designed to provide more than 65,000 times the 32 bit limit of 4 GB
Gigabyte
The gigabyte is a multiple of the unit byte for digital information storage. The prefix giga means 109 in the International System of Units , therefore 1 gigabyte is...
, allowing ample room for expansion in the near future without incurring the overhead of translating full 64-bit addresses.
64-bit processor timeline
1961: IBM delivers the IBM 7030 Stretch supercomputer
Supercomputer
A supercomputer is a computer at the frontline of current processing capacity, particularly speed of calculation.Supercomputers are used for highly calculation-intensive tasks such as problems including quantum physics, weather forecasting, climate research, molecular modeling A supercomputer is a...
, which uses 64-bit data words and 32- or 64-bit instruction words.
1974: Control Data Corporation
Control Data Corporation
Control Data Corporation was a supercomputer firm. For most of the 1960s, it built the fastest computers in the world by far, only losing that crown in the 1970s after Seymour Cray left the company to found Cray Research, Inc....
The STAR-100 was a vector supercomputer designed, manufactured, and marketed by Control Data Corporation . It was one of the first machines to use a vector processor to improve performance on appropriate scientific applications....
vector supercomputer, which uses a 64-bit word architecture (previous CDC systems were based on a 60-bit architecture).
International Computers Limited launches the ICL 2900 Series
ICL 2900 Series
The ICL 2900 Series was a range of mainframe computer systems announced by the UK manufacturer ICL on 9 October 1974. The company had started development, under the name "New Range" immediately on its formation in 1968...
The two's complement of a binary number is defined as the value obtained by subtracting the number from a large power of two...
integers; 64-bit and 128-bit floating point; 32-bit, 64-bit and 128-bit packed decimal and a 128-bit accumulator register. The architecture has survived through a succession of ICL and Fujitsu machines. The latest is the Fujitsu Supernova, which emulates the original environment on 64-bit Intel processors.
The Cray-1 was a supercomputer designed, manufactured, and marketed by Cray Research. The first Cray-1 system was installed at Los Alamos National Laboratory in 1976, and it went on to become one of the best known and most successful supercomputers in history...
supercomputer, which is based on a 64-bit word architecture and will form the basis for later Cray vector supercomputers.
1983: Elxsi
Elxsi
Elxsi was a minicomputer manufacturing company established in the late 1970s along with a host of other competitors . The Elxsi processor was an Emitter Coupled Logic design that featured a 50 nanosecond clock, a 25 nanosecond backpanel bus, IEEE floating point arithmetic and a 64-bit architecture...
Minisupercomputers constituted a short-lived class of computers that emerged in the mid-1980s. As scientific computing using vector processors became more popular, the need for lower-cost systems that might be used at the departmental level instead of the corporate level created an opportunity for...
. The Elxsi architecture has 64-bit data registers but a 32-bit address space.
1989: Intel introduces the Intel i860
Intel i860
The Intel i860 was a RISC microprocessor from Intel, first released in 1989. The i860 was one of Intel's first attempts at an entirely new, high-end instruction set since the failed Intel i432 from the 1980s...
RISC processor. Marketed as a "64-Bit Microprocessor", it had essentially a 32-bit architecture, enhanced with a 3D Graphics Unit capable of 64-bit integer operations.
1991: MIPS Technologies
MIPS Technologies
MIPS Technologies, Inc. , formerly MIPS Computer Systems, Inc., is most widely known for developing the MIPS architecture and a series of pioneering RISC chips. MIPS provides processor architectures and cores for digital home, networking and mobile applications.MIPS Computer Systems Inc. was...
produces the first 64-bit microprocessor, the R4000
R4000
The R4000 is a microprocessor developed by MIPS Computer Systems that implemented the MIPS III instruction set architecture . Officially announced on 1 October 1991, it was one of the first 64-bit microprocessors and the first MIPS III implementation...
, which implements the MIPS III ISA, the third revision of their MIPS architecture
MIPS architecture
MIPS is a reduced instruction set computer instruction set architecture developed by MIPS Technologies . The early MIPS architectures were 32-bit, and later versions were 64-bit...
Silicon Graphics, Inc. was a manufacturer of high-performance computing solutions, including computer hardware and software, founded in 1981 by Jim Clark...
graphics workstations starting with the IRIS Crimson
SGI Crimson
The IRIS Crimson, code named Diehard2, is a Silicon Graphics computer released in the early 1990s. It was the world's first 64-bit workstation....
Kendall Square Research was a supercomputer company headquartered originally in Kendall Square in Cambridge, Massachusetts in 1986, near MIT. It was co-founded by Steven Frank and Henry Burkhardt III, who had previously helped found Data General and Encore Computer and was one of the original...
deliver their first KSR1 supercomputer, based on a proprietary 64-bit RISC processor architecture running OSF/1.
1992: Digital Equipment Corporation
Digital Equipment Corporation
Digital Equipment Corporation was a major American company in the computer industry and a leading vendor of computer systems, software and peripherals from the 1960s to the 1990s...
Alpha, originally known as Alpha AXP, is a 64-bit reduced instruction set computer instruction set architecture developed by Digital Equipment Corporation , designed to replace the 32-bit VAX complex instruction set computer ISA and its implementations. Alpha was implemented in microprocessors...
PRISM was a 32-bit RISC instruction set architecture developed by Digital Equipment Corporation . It was the final outcome of a number of DEC research projects from the 1982–1985 time-frame, and was at the point of delivering silicon in 1988 when the management canceled the project...
Atari is a corporate and brand name owned by several entities since its inception in 1972. It is currently owned by Atari Interactive, a wholly owned subsidiary of the French publisher Atari, SA . The original Atari, Inc. was founded in 1972 by Nolan Bushnell and Ted Dabney. It was a pioneer in...
The Atari Jaguar is a video game console that was released by Atari Corporation in 1993. It was the last to be marketed under the Atari brand until the release of the Atari Flashback in 2004. It was designed to surpass the Mega Drive/Genesis, Super Nintendo Entertainment System, and the Panasonic...
A video game console is an interactive entertainment computer or customized computer system that produces a video display signal which can be used with a display device to display a video game...
, which includes some 64-bit wide data paths in its architecture.
1994: Intel announces plans for the 64-bit IA-64 architecture (jointly developed with Hewlett-Packard
Hewlett-Packard
Hewlett-Packard Company or HP is an American multinational information technology corporation headquartered in Palo Alto, California, USA that provides products, technologies, softwares, solutions and services to consumers, small- and medium-sized businesses and large enterprises, including...
IA-32 , also known as x86-32, i386 or x86, is the CISC instruction-set architecture of Intel's most commercially successful microprocessors, and was first implemented in the Intel 80386 as a 32-bit extension of x86 architecture...
processors. A 1998 to 1999 launch date is targeted.
1995: Sun
Sun Microsystems
Sun Microsystems, Inc. was a company that sold :computers, computer components, :computer software, and :information technology services. Sun was founded on February 24, 1982...
The UltraSPARC is a microprocessor developed by Sun Microsystems who is now a part of Oracle Corporation and fabricated by Texas Instruments that implements the SPARC V9 instruction set architecture . It was introduced in mid-1995. It was the first microprocessor from Sun Microsystems to implement...
is a Japanese multinational information technology equipment and services company headquartered in Tokyo, Japan. It is the world's third-largest IT services provider measured by revenues....
HAL Computer Systems, Inc was a Campbell, California-based computer manufacturer founded in 1990 by Andrew Heller, a principal designer of the original IBM POWER architecture...
launches workstations based on a 64-bit CPU, HAL's independently designed first-generation SPARC64
SPARC64
SPARC64 is a microprocessor developed by HAL Computer Systems and fabricated by Fujitsu. It implements the SPARC V9 instruction set architecture , the first microprocessor to do so. SPARC64 was HAL's first microprocessor and was the first in the SPARC64 brand. It operates at 101 and 118 MHz...
. IBM releases the A10 and A30 microprocessors, 64-bit PowerPC AS processors. IBM also releases a 64-bit AS/400 system upgrade, which can convert the operating system, database and applications.
1996: Nintendo
Nintendo
is a multinational corporation located in Kyoto, Japan. Founded on September 23, 1889 by Fusajiro Yamauchi, it produced handmade hanafuda cards. By 1963, the company had tried several small niche businesses, such as a cab company and a love hotel....
The , often referred to as N64, was Nintendo′s third home video game console for the international market. Named for its 64-bit CPU, it was released in June 1996 in Japan, September 1996 in North America, March 1997 in Europe and Australia, September 1997 in France and December 1997 in Brazil...
video game console, built around a low-cost variant of the MIPS R4000. HP releases an implementation of the 64-bit 2.0 version of their PA-RISC
PA-RISC
PA-RISC is an instruction set architecture developed by Hewlett-Packard. As the name implies, it is a reduced instruction set computer architecture, where the PA stands for Precision Architecture...
The PA-8000 , code-named Onyx, is a microprocessor developed and fabricated by Hewlett-Packard that implemented the PA-RISC 2.0 instruction set architecture . It was a completely new design with no circuitry derived from previous PA-RISC microprocessors...
.
1997: IBM releases the RS64 line of 64-bit PowerPC
PowerPC
PowerPC is a RISC architecture created by the 1991 Apple–IBM–Motorola alliance, known as AIM...
/PowerPC AS processors.
1998: IBM releases the POWER3
POWER3
The POWER3 is a microprocessor, designed and exclusively manufactured by IBM, that implemented the 64-bit version of the PowerPC instruction set architecture , including all of the optional instructions of the ISA such as the POWER2. It was introduced on 5 October 1998, debuting in the RS/6000 43P...
POWER is a reduced instruction set computer instruction set architecture developed by IBM. The name is an acronym for Performance Optimization With Enhanced RISC....
An instruction set, or instruction set architecture , is the part of the computer architecture related to programming, including the native data types, instructions, registers, addressing modes, memory architecture, interrupt and exception handling, and external I/O...
for the IA-64 architecture. AMD publicly discloses its set of 64-bit extensions to IA-32, called x86-64
X86-64
x86-64 is an extension of the x86 instruction set. It supports vastly larger virtual and physical address spaces than are possible on x86, thereby allowing programmers to conveniently work with much larger data sets. x86-64 also provides 64-bit general purpose registers and numerous other...
(later branded AMD64).
2000: IBM ships its first 64-bit z/Architecture
Z/Architecture
z/Architecture, initially and briefly called ESA Modal Extensions , refers to IBM's 64-bit computing architecture for IBM mainframe computers. IBM introduced its first z/Architecture-based system, the zSeries Model 900, in late 2000. Later z/Architecture systems include the IBM z800, z990, z890,...
Mainframes are powerful computers used primarily by corporate and governmental organizations for critical applications, bulk data processing such as census, industry and consumer statistics, enterprise resource planning, and financial transaction processing.The term originally referred to the...
IBM System z, or earlier IBM eServer zSeries, is a brand name designated by IBM to all its mainframe computers.In 2000, IBM rebranded the existing System/390 to IBM eServer zSeries with the e depicted in IBM's red trademarked symbol, but because no specific machine names were changed for...
z900. z/Architecture is a 64-bit version of the 32-bit ESA/390
ESA/390
ESA/390 was introduced in September 1990 and is IBM's last 31-bit-address/32-bit-data mainframe computing design, copied by Amdahl, Hitachi, and Fujitsu among other competitors...
architecture, a descendant of the 32-bit System/360
System/360
The IBM System/360 was a mainframe computer system family first announced by IBM on April 7, 1964, and sold between 1964 and 1978. It was the first family of computers designed to cover the complete range of applications, from small to large, both commercial and scientific...
architecture.
2001: Intel finally ships its IA-64 processor line, after repeated delays in getting to market. Now branded Itanium
Itanium
Itanium is a family of 64-bit Intel microprocessors that implement the Intel Itanium architecture . Intel markets the processors for enterprise servers and high-performance computing systems...
and targeting high-end servers, sales fail to meet expectations.
2003: AMD introduces its Opteron
Opteron
Opteron is AMD's x86 server and workstation processor line, and was the first processor which supported the AMD64 instruction set architecture . It was released on April 22, 2003 with the SledgeHammer core and was intended to compete in the server and workstation markets, particularly in the same...
The Athlon 64 is an eighth-generation, AMD64-architecture microprocessor produced by AMD, released on September 23, 2003. It is the third processor to bear the name Athlon, and the immediate successor to the Athlon XP...
processor lines, based on its AMD64 architecture which is the first x86-based 64-bit processor architecture. Apple
Apple Computer
Apple Inc. is an American multinational corporation that designs and markets consumer electronics, computer software, and personal computers. The company's best-known hardware products include the Macintosh line of computers, the iPod, the iPhone and the iPad...
The PowerPC 970, PowerPC 970FX, PowerPC 970GX, and PowerPC 970MP, are 64-bit Power Architecture processors from IBM introduced in 2002. When used in Apple Inc. machines, they were dubbed the PowerPC G5....
CPU produced by IBM. Intel maintains that its Itanium chips would remain its only 64-bit processors.
2004: Intel, reacting to the market success of AMD, admits it has been developing a clone of the AMD64 extensions named IA-32e (later renamed EM64T, then yet again renamed to Intel 64). Intel ships updated versions of its Xeon
Xeon
The Xeon is a brand of multiprocessing- or multi-socket-capable x86 microprocessors from Intel Corporation targeted at the non-consumer server, workstation and embedded system markets.-Overview:...
Pentium 4 was a line of single-core desktop and laptop central processing units , introduced by Intel on November 20, 2000 and shipped through August 8, 2008. They had a 7th-generation x86 microarchitecture, called NetBurst, which was the company's first all-new design since the introduction of the...
processor families supporting the new 64-bit instruction set.
VIA Technologies is a Taiwanese manufacturer of integrated circuits, mainly motherboard chipsets, CPUs, and memory, and is part of the Formosa Plastics Group. It is the world's largest independent manufacturer of motherboard chipsets...
announces the Isaiah 64-bit processor.
2006: Sony, IBM, and Toshiba begin manufacturing of the 64-bit Cell processor
Cell (microprocessor)
Cell is a microprocessor architecture jointly developed by Sony, Sony Computer Entertainment, Toshiba, and IBM, an alliance known as "STI". The architectural design and first implementation were carried out at the STI Design Center in Austin, Texas over a four-year period beginning March 2001 on a...
The is the third home video game console produced by Sony Computer Entertainment and the successor to the PlayStation 2 as part of the PlayStation series. The PlayStation 3 competes with Microsoft's Xbox 360 and Nintendo's Wii as part of the seventh generation of video game consoles...
Cray Inc. is an American supercomputer manufacturer based in Seattle, Washington. The company's predecessor, Cray Research, Inc. , was founded in 1972 by computer designer Seymour Cray. Seymour Cray went on to form the spin-off Cray Computer Corporation , in 1989, which went bankrupt in 1995,...
UNICOS is the name of a range of Unix-like operating system variants developed by Cray for its supercomputers. UNICOS is the successor of the Cray Operating System . It provides network clustering and source code compatibility layers for some other Unixes. UNICOS was originally introduced in 1985...
Unix is a multitasking, multi-user computer operating system originally developed in 1969 by a group of AT&T employees at Bell Labs, including Ken Thompson, Dennis Ritchie, Brian Kernighan, Douglas McIlroy, and Joe Ossanna...
operating system.
1993: DEC releases the 64-bit DEC OSF/1 AXP Unix-like
Unix-like
A Unix-like operating system is one that behaves in a manner similar to a Unix system, while not necessarily conforming to or being certified to any version of the Single UNIX Specification....
operating system (later renamed Tru64 UNIX) for its systems based on the Alpha
DEC Alpha
Alpha, originally known as Alpha AXP, is a 64-bit reduced instruction set computer instruction set architecture developed by Digital Equipment Corporation , designed to replace the 32-bit VAX complex instruction set computer ISA and its implementations. Alpha was implemented in microprocessors...
MIPS is a reduced instruction set computer instruction set architecture developed by MIPS Technologies . The early MIPS architectures were 32-bit, and later versions were 64-bit...
The R8000 is a microprocessor chipset developed by MIPS Technologies, Inc. , Toshiba, and Weitek. It was the first implementation of the MIPS IV instruction set architecture. The R8000 is also known as the TFP, for Tremendous Floating-Point, its name during development.-History:Development of the...
Silicon Graphics, Inc. was a manufacturer of high-performance computing solutions, including computer hardware and software, founded in 1981 by Jim Clark...
IRIX is a computer operating system developed by Silicon Graphics, Inc. to run natively on their 32- and 64-bit MIPS architecture workstations and servers. It was based on UNIX System V with BSD extensions. IRIX was the first operating system to include the XFS file system.The last major version...
An operating system is a set of programs that manage computer hardware resources and provide common services for application software. The operating system is the most important type of system software in a computer system...
OpenVMS , previously known as VAX-11/VMS, VAX/VMS or VMS, is a computer server operating system that runs on VAX, Alpha and Itanium-based families of computers. Contrary to what its name suggests, OpenVMS is not open source software; however, the source listings are available for purchase...
7.0, the first full 64-bit version of OpenVMS for Alpha. First 64-bit Linux distribution
Linux distribution
A Linux distribution is a member of the family of Unix-like operating systems built on top of the Linux kernel. Such distributions are operating systems including a large collection of software applications such as word processors, spreadsheets, media players, and database applications...
for the Alpha architecture is released.
1996: Support for the MIPS
MIPS architecture
MIPS is a reduced instruction set computer instruction set architecture developed by MIPS Technologies . The early MIPS architectures were 32-bit, and later versions were 64-bit...
The R4000 is a microprocessor developed by MIPS Computer Systems that implemented the MIPS III instruction set architecture . Officially announced on 1 October 1991, it was one of the first 64-bit microprocessors and the first MIPS III implementation...
Silicon Graphics, Inc. was a manufacturer of high-performance computing solutions, including computer hardware and software, founded in 1981 by Jim Clark...
IRIX is a computer operating system developed by Silicon Graphics, Inc. to run natively on their 32- and 64-bit MIPS architecture workstations and servers. It was based on UNIX System V with BSD extensions. IRIX was the first operating system to include the XFS file system.The last major version...
An operating system is a set of programs that manage computer hardware resources and provide common services for application software. The operating system is the most important type of system software in a computer system...
in release 6.2.
1998: Sun releases Solaris 7, with full 64-bit UltraSPARC
UltraSPARC
The UltraSPARC is a microprocessor developed by Sun Microsystems who is now a part of Oracle Corporation and fabricated by Texas Instruments that implements the SPARC V9 instruction set architecture . It was introduced in mid-1995. It was the first microprocessor from Sun Microsystems to implement...
z/OS is a 64-bit operating system for mainframe computers, produced by IBM. It derives from and is the successor to OS/390, which in turn followed a string of MVS versions.Starting with earliest:*OS/VS2 Release 2 through Release 3.8...
Multiple Virtual Storage, more commonly called MVS, was the most commonly used operating system on the System/370 and System/390 IBM mainframe computers...
IBM System z, or earlier IBM eServer zSeries, is a brand name designated by IBM to all its mainframe computers.In 2000, IBM rebranded the existing System/390 to IBM eServer zSeries with the e depicted in IBM's red trademarked symbol, but because no specific machine names were changed for...
64-bit mainframes; 64-bit Linux on zSeries follows the CPU release almost immediately.
2001: Microsoft releases Windows XP 64-Bit Edition for the Itanium
Itanium
Itanium is a family of 64-bit Intel microprocessors that implement the Intel Itanium architecture . Intel markets the processors for enterprise servers and high-performance computing systems...
On the x86 architecture, a 32-bit application normally means software that typically uses the 32-bit linear address space possible with the 80386 and later chips...
s through an execution layer.
2003: Apple releases its Mac OS X 10.3 "Panther" operating system which adds support for native 64-bit integer arithmetic on PowerPC 970
PowerPC 970
The PowerPC 970, PowerPC 970FX, PowerPC 970GX, and PowerPC 970MP, are 64-bit Power Architecture processors from IBM introduced in 2002. When used in Apple Inc. machines, they were dubbed the PowerPC G5....
Linux is a Unix-like computer operating system assembled under the model of free and open source software development and distribution. The defining component of any Linux system is the Linux kernel, an operating system kernel first released October 5, 1991 by Linus Torvalds...
A Linux distribution is a member of the family of Unix-like operating systems built on top of the Linux kernel. Such distributions are operating systems including a large collection of software applications such as word processors, spreadsheets, media players, and database applications...
Microsoft Corporation is an American public multinational corporation headquartered in Redmond, Washington, USA that develops, manufactures, licenses, and supports a wide range of products and services predominantly related to computing through its various product divisions...
announces plans to create a version of its Windows
Microsoft Windows
Microsoft Windows is a series of operating systems produced by Microsoft.Microsoft introduced an operating environment named Windows on November 20, 1985 as an add-on to MS-DOS in response to the growing interest in graphical user interfaces . Microsoft Windows came to dominate the world's personal...
operating system to support the AMD64 architecture, with backwards compatibility with 32-bit applications. FreeBSD
FreeBSD
FreeBSD is a free Unix-like operating system descended from AT&T UNIX via BSD UNIX. Although for legal reasons FreeBSD cannot be called “UNIX”, as the direct descendant of BSD UNIX , FreeBSD’s internals and system APIs are UNIX-compliant...
releases with support for AMD64.
2005: On January 31, Sun releases Solaris 10 with support for AMD64 and EM64T processors. On April 29, Apple releases Mac OS X 10.4 "Tiger" which provides limited support for 64-bit command-line applications on machines with PowerPC 970 processors; later versions for Intel-based Macs supported 64-bit command-line applications on Macs with EM64T processors. On April 30, Microsoft releases Windows XP Professional x64 Edition
Windows XP Professional x64 Edition
Microsoft Windows XP Professional x64 Edition released on April 25, 2005 is an edition of Windows XP for x86-64 personal computers. It is designed to use the expanded 64-bit memory address space provided by the x86-64 architecture....
for AMD64 and EM64T processors.
2006: Microsoft releases Windows Vista
Windows Vista
Windows Vista is an operating system released in several variations developed by Microsoft for use on personal computers, including home and business desktops, laptops, tablet PCs, and media center PCs...
, including a 64-bit version for AMD64/EM64T processors that retains 32-bit compatibility. In the 64-bit version, all Windows applications and components are 64-bit, although many also have their 32-bit versions included for compatibility with plugins.
2007: Apple releases Mac OS X 10.5 "Leopard", which fully supports 64-bit applications on machines with PowerPC 970 or EM64T processors.
2009: Apple releases Mac OS X 10.6, "Snow Leopard," which ships with a 64-bit kernel for AMD64/Intel64 processors, although only certain recent models of Apple computers will run the 64-bit kernel by default. Most applications bundled with Mac OS X 10.6 are now also 64-bit. Microsoft releases Windows 7, which, like Windows Vista, includes a full 64-bit version for AMD64/Intel 64 processors; most new computers are loaded by default with a 64-bit version. It also releases Windows Server 2008 R2
Windows Server 2008 R2
Windows Server 2008 R2 is a server operating system produced by Microsoft. It was released to manufacturing on July 22, 2009 and launched on October 22, 2009. According to the Windows Server Team blog, the retail availability was September 14, 2009. It is built on Windows NT 6.1, the same core...
, which is the first 64-bit only operating system released by Microsoft.
2011: Apple releases Mac OS X 10.7, "Lion," which runs the 64-bit kernel by default on supported machines. Older machines that are unable to run the 64-bit kernel run the 32-bit kernel, but, as with earlier releases, can still run 64-bit applications; Lion does not support machines with 32-bit processors. Nearly all applications bundled with Mac OS X 10.7 are now also 64-bit, including iTunes.
The range of integer values that can be stored in 32 bits is 0 through 4,294,967,295. Hence, a processor with 32-bit memory addresses can directly access 4 GB of byte-addressable memory....
to a 64-bit architecture is a fundamental alteration, as most operating system
Operating system
An operating system is a set of programs that manage computer hardware resources and provide common services for application software. The operating system is the most important type of system software in a computer system...
s must be extensively modified to take advantage of the new architecture, because that software has to manage the actual memory addressing hardware. Other software must also be ported
Porting
In computer science, porting is the process of adapting software so that an executable program can be created for a computing environment that is different from the one for which it was originally designed...
to use the new capabilities; older software is usually supported through either a hardware compatibility mode (in which the new processors support the older 32-bit version of the instruction set as well as the 64-bit version), through software emulation
Emulator
In computing, an emulator is hardware or software or both that duplicates the functions of a first computer system in a different second computer system, so that the behavior of the second system closely resembles the behavior of the first system...
, or by the actual implementation of a 32-bit processor core within the 64-bit processor (as with the Itanium processors from Intel, which include an IA-32
IA-32
IA-32 , also known as x86-32, i386 or x86, is the CISC instruction-set architecture of Intel's most commercially successful microprocessors, and was first implemented in the Intel 80386 as a 32-bit extension of x86 architecture...
processor core to run 32-bit x86 applications). The operating systems for those 64-bit architectures generally support both 32-bit and 64-bit applications.
One significant exception to this is the AS/400, whose software runs on a virtual ISA, called TIMI (Technology Independent Machine Interface) which is translated to native machine code by low-level software before being executed. The low-level software is all that has to be rewritten to move the entire OS and all software to a new platform, such as when IBM transitioned their line from the older 32/48-bit "IMPI" instruction set to 64-bit PowerPC (IMPI wasn't anything like 32-bit PowerPC, so this was an even bigger transition than from a 32-bit version of an instruction set to a 64-bit version of the same instruction set).
While 64-bit architectures indisputably make working with large data sets in applications such as digital video
Digital video
Digital video is a type of digital recording system that works by using a digital rather than an analog video signal.The terms camera, video camera, and camcorder are used interchangeably in this article.- History :...
A database is an organized collection of data for one or more purposes, usually in digital form. The data are typically organized to model relevant aspects of reality , in a way that supports processes requiring this information...
s easier, there has been considerable debate as to whether they or their 32-bit compatibility modes will be faster than comparably-priced 32-bit systems for other tasks. In x86-64
X86-64
x86-64 is an extension of the x86 instruction set. It supports vastly larger virtual and physical address spaces than are possible on x86, thereby allowing programmers to conveniently work with much larger data sets. x86-64 also provides 64-bit general purpose registers and numerous other...
architecture (AMD64), the majority of the 32-bit operating systems and applications are able to run smoothly on the 64-bit hardware.
A compiled Java program can run on a 32 bit or 64 bit Java virtual machine without modification. The lengths and precision of all the built in types are specified by the standard and are not dependent on the underlying architecture. Java programs that run on a 64 bit Java virtual machine have access to a larger address space.
Speed is not the only factor to consider in a comparison of 32-bit and 64-bit processors. Applications such as multi-tasking, stress testing, and clustering—for HPC (high-performance computing
High-performance computing
High-performance computing uses supercomputers and computer clusters to solve advanced computation problems. Today, computer systems approaching the teraflops-region are counted as HPC-computers.-Overview:...
)—may be more suited to a 64-bit architecture when deployed appropriately. 64-bit clusters have been widely deployed in large organizations such as IBM, HP, and Microsoft, for this reason.
Pros and cons
A common misconception is that 64-bit architectures are no better than 32-bit architectures unless the computer has more than 4 GB of random access memory. This is not entirely true:
Some operating systems and certain hardware configurations limit the physical memory space to 3 GB on IA-32
IA-32
IA-32 , also known as x86-32, i386 or x86, is the CISC instruction-set architecture of Intel's most commercially successful microprocessors, and was first implemented in the Intel 80386 as a 32-bit extension of x86 architecture...
systems, due to much of the 3–4 GB region being reserved for hardware addressing; see 3 GB barrier
3 GB barrier
In computing, the 3 GB barrier is a limitation of some 32-bit operating systems running on x86 microprocessors. It prevents the operating systems from using more than about 3 GB of main memory...
. This is not present in 64-bit architectures, which can use 4 GB of memory and more. However, IA-32 processors from the Pentium II
Pentium II
The Pentium II brand refers to Intel's sixth-generation microarchitecture and x86-compatible microprocessors introduced on May 7, 1997. Containing 7.5 million transistors, the Pentium II featured an improved version of the first P6-generation core of the Pentium Pro, which contained 5.5 million...
In computing, Physical Address Extension is a feature to allow x86 processors to access a physical address space larger than 4 gigabytes....
(PAE), which gives a 64 GB physical address range, of which up to 62 GB may be used by main memory; operating systems that support PAE may not be limited to 4GB of physical memory, even on IA-32 processors.
Some operating systems reserve portions of process
Process (computing)
In computing, a process is an instance of a computer program that is being executed. It contains the program code and its current activity. Depending on the operating system , a process may be made up of multiple threads of execution that execute instructions concurrently.A computer program is a...
In computing, an address space defines a range of discrete addresses, each of which may correspond to a network host, peripheral device, disk sector, a memory cell or other logical or physical entity.- Overview :...
for OS use, effectively reducing the total address space available for mapping memory for user programs. For instance, Windows XP DLLs and other user mode OS components are mapped into each process's address space, leaving only 2 to 3 GB (depending on the settings) address space available. This limit is currently much higher on 64-bit operating systems and does not realistically restrict memory usage yet.
A memory-mapped file is a segment of virtual memory which has been assigned a direct byte-for-byte correlation with some portion of a file or file-like resource. This resource is typically a file that is physically present on-disk, but can also be a device, shared memory object, or other resource...
s are becoming more difficult to implement in 32-bit architectures. A 4 GB file is no longer uncommon, and such large files cannot be memory mapped easily to 32-bit architectures; only a region of the file can be mapped into the address space, and to access such a file by memory mapping, those regions will have to be mapped into and out of the address space as needed. This is a problem, as memory mapping remains one of the most efficient disk-to-memory methods, when properly implemented by the OS.
Some programs such as encoders, decoders and encryption software can benefit greatly from 64-bit registers (if the software is 64-bit compiled), while the performance of other programs, such as 3D graphics-oriented ones, remains unaffected when switching from a 32-bit environment to a 64-bit one. It is unusual for a 64-bit program to perform worse than its 32-bit equivalent and usually only happens due to a bug.
x86-64 is an extension of the x86 instruction set. It supports vastly larger virtual and physical address spaces than are possible on x86, thereby allowing programmers to conveniently work with much larger data sets. x86-64 also provides 64-bit general purpose registers and numerous other...
, allow for more general purpose registers than their 32-bit counterparts. This is a significant speed increase for tight loops since the processor does not have to fetch data from the cache or main memory if the data can fit in the available registers.
C is a general-purpose computer programming language developed between 1969 and 1973 by Dennis Ritchie at the Bell Telephone Laboratories for use with the Unix operating system....
:
int a, b, c, d, e;
for (a=0; a<100; a++)
{
b = a;
c = b;
d = c;
e = d;
}
If a processor only has the ability to keep two or three values/variables in registers it would need to move some values between memory and registers to be able to process variables d and e as well; this is a process that takes a lot of CPU cycles. A processor that is capable of holding all the values/variables in registers can simply just loop through this without needing to move data between registers and memory for each iteration. This behavior can easily be compared with virtual memory, although any effects are contingent upon the compiler.
The main disadvantage of 64-bit architectures is that relative to 32-bit architectures, the same data occupies more space in memory (due to swollen pointers and possibly other types and alignment padding). This increases the memory requirements of a given process and can have implications for efficient processor cache utilization. Maintaining a partial 32-bit model is one way to handle this and is in general reasonably effective. For example, the z/OS
Z/OS
z/OS is a 64-bit operating system for mainframe computers, produced by IBM. It derives from and is the successor to OS/390, which in turn followed a string of MVS versions.Starting with earliest:*OS/VS2 Release 2 through Release 3.8...
operating system takes this approach currently, requiring program code to reside in 31-bit address spaces (the high order bit is not used in address calculation on the underlying hardware platform) while data objects can optionally reside in 64-bit regions.
, most proprietary x86 software is compiled into 32-bit code, with less being also compiled into 64-bit code (although the trend is rapidly equalizing ), so much does not take advantage of the larger 64-bit address space or wider 64-bit registers and data paths on x86 processors, or the additional registers in 64-bit mode. However, users of most RISC platforms, and users of free
Free software
Free software, software libre or libre software is software that can be used, studied, and modified without restriction, and which can be copied and redistributed in modified or unmodified form either without restriction, or with restrictions that only ensure that further recipients can also do...
The term open source describes practices in production and development that promote access to the end product's source materials. Some consider open source a philosophy, others consider it a pragmatic methodology...
In computer science, source code is text written using the format and syntax of the programming language that it is being written in. Such a language is specially designed to facilitate the work of computer programmers, who specify the actions to be performed by a computer mostly by writing source...
is available for recompiling with a 64-bit compiler) have been able to use exclusive 64-bit computing environments for years. Not all such applications require a large address space nor manipulate 64-bit data items, so they wouldn't benefit from the larger address space or wider registers and data paths. The main advantage to 64-bit versions of such applications is the ability to access more registers in the x86-64
X86-64
x86-64 is an extension of the x86 instruction set. It supports vastly larger virtual and physical address spaces than are possible on x86, thereby allowing programmers to conveniently work with much larger data sets. x86-64 also provides 64-bit general purpose registers and numerous other...
architecture.
Software availability
x86-based 64-bit systems sometimes lack equivalents to software that is written for 32-bit architectures. The most severe problem in Microsoft Windows is incompatible device driver
Device driver
In computing, a device driver or software driver is a computer program allowing higher-level computer programs to interact with a hardware device....
s. Most 32-bit application software can run on a 64-bit operating system in a compatibility mode, also known as an emulation
Emulator
In computing, an emulator is hardware or software or both that duplicates the functions of a first computer system in a different second computer system, so that the behavior of the second system closely resembles the behavior of the first system...
WoW64 is a subsystem of the Windows operating system that is capable of running 32-bit applications and is included on all 64-bit versions of Windows—including Windows XP Professional x64 Edition, IA-64 and x64 versions of Windows Server 2003, as well as 64-bit versions of Windows Vista, Windows...
Technology for IA-64 and AMD64. The 64-bit Windows Native Mode driver environment runs atop 64-bit NTDLL.DLL which cannot call 32-bit Win32 subsystem code (often devices whose actual hardware function is emulated in user mode software, like Winprinters). Because 64-bit drivers for most devices were not available until early 2007 (Vista x64), using 64-bit Microsoft Windows operating system was considered a challenge. However, the trend is changing towards 64-bit computing as most manufacturers provide both 32-bit and 64-bit drivers nowadays, so this issue is most likely to occur when attempting to use older peripherals.
This is less of a problem with open source drivers that are already available for a 32-bit OS, since they can be modified to be 64-bit compatible, if necessary. Furthermore, support for hardware made before early 2007 was equally troubling for opensource platforms due to their small market shares in desktop market.
Mac OS X is a series of Unix-based operating systems and graphical user interfaces developed, marketed, and sold by Apple Inc. Since 2002, has been included with all new Macintosh computer systems...
runs with a 32-bit kernel even on 64-bit-capable processors, but the 32-bit kernel can run 64-bit user-mode code; this allows those Macs to support 64-bit processes while still supporting 32-bit device drivers - although not 64-bit drivers and performance advantages that would come with them. On systems with 64-bit processors, both the 32-bit and 64-bit Mac OS X kernel can run 32-bit user-mode code, and all versions of Mac OS X include 32-bit versions of libraries that 32-bit applications would use, so 32-bit user-mode software for Mac OS X will run on those systems.
Linux is a Unix-like computer operating system assembled under the model of free and open source software development and distribution. The defining component of any Linux system is the Linux kernel, an operating system kernel first released October 5, 1991 by Linus Torvalds...
A Unix-like operating system is one that behaves in a manner similar to a Unix system, while not necessarily conforming to or being certified to any version of the Single UNIX Specification....
C is a general-purpose computer programming language developed between 1969 and 1973 by Dennis Ritchie at the Bell Telephone Laboratories for use with the Unix operating system....
C++ is a statically typed, free-form, multi-paradigm, compiled, general-purpose programming language. It is regarded as an intermediate-level language, as it comprises a combination of both high-level and low-level language features. It was developed by Bjarne Stroustrup starting in 1979 at Bell...
toolchains for them, have supported 64-bit processors for many years: releasing 64-bit versions of their operating system before official Microsoft releases. Many applications and libraries for those platforms are open source
Open source
The term open source describes practices in production and development that promote access to the end product's source materials. Some consider open source a philosophy, others consider it a pragmatic methodology...
, written in C and C++, so that, if it is 64-bit-safe, they can be compiled into 64-bit versions. This source-based distribution model with an emphasis on frequent releases and cutting-edge code makes availability of application software for those operating systems less of an issue.
64-bit data models
In 32-bit programs, pointers and data types such as integers generally have the same length; this is not necessarily true on 64-bit machines. Mixing data types in programming languages such as C
C (programming language)
C is a general-purpose computer programming language developed between 1969 and 1973 by Dennis Ritchie at the Bell Telephone Laboratories for use with the Unix operating system....
C++ is a statically typed, free-form, multi-paradigm, compiled, general-purpose programming language. It is regarded as an intermediate-level language, as it comprises a combination of both high-level and low-level language features. It was developed by Bjarne Stroustrup starting in 1979 at Bell...
Objective-C is a reflective, object-oriented programming language that adds Smalltalk-style messaging to the C programming language.Today, it is used primarily on Apple's Mac OS X and iOS: two environments derived from the OpenStep standard, though not compliant with it...
may thus function on 32-bit implementations but not on 64-bit implementations.
In many programming environments for C and C-derived languages on 64-bit machines, "int" variables are still 32 bits wide, but long integers and pointers are 64 bits wide. These are described as having an LP64data model
Data model
A data model in software engineering is an abstract model, that documents and organizes the business data for communication between team members and is used as a plan for developing applications, specifically how data is stored and accessed....
. Another alternative is the ILP64 data model in which all three data types are 64 bits wide, and even SILP64 where "short" integers are also 64 bits wide. However, in most cases the modifications required are relatively minor and straightforward, and many well-written programs can simply be recompiled for the new environment without changes. Another alternative is the LLP64 model, which maintains compatibility with 32-bit code by leaving both int and long as 32-bit. "LL" refers to the "long long integer" type, which is at least 64 bits on all platforms, including 32-bit environments.
Microsoft Windows is a series of operating systems produced by Microsoft.Microsoft introduced an operating environment named Windows on November 20, 1985 as an add-on to MS-DOS in response to the growing interest in graphical user interfaces . Microsoft Windows came to dominate the world's personal...
Unix is a multitasking, multi-user computer operating system originally developed in 1969 by a group of AT&T employees at Bell Labs, including Ken Thompson, Dennis Ritchie, Brian Kernighan, Douglas McIlroy, and Joe Ossanna...
A Unix-like operating system is one that behaves in a manner similar to a Unix system, while not necessarily conforming to or being certified to any version of the Single UNIX Specification....
Linux is a Unix-like computer operating system assembled under the model of free and open source software development and distribution. The defining component of any Linux system is the Linux kernel, an operating system kernel first released October 5, 1991 by Linus Torvalds...
Mac OS X is a series of Unix-based operating systems and graphical user interfaces developed, marketed, and sold by Apple Inc. Since 2002, has been included with all new Macintosh computer systems...
z/OS is a 64-bit operating system for mainframe computers, produced by IBM. It derives from and is the successor to OS/390, which in turn followed a string of MVS versions.Starting with earliest:*OS/VS2 Release 2 through Release 3.8...
HAL Computer Systems, Inc was a Campbell, California-based computer manufacturer founded in 1990 by Andrew Heller, a principal designer of the original IBM POWER architecture...
SPARC64 is a microprocessor developed by HAL Computer Systems and fabricated by Fujitsu. It implements the SPARC V9 instruction set architecture , the first microprocessor to do so. SPARC64 was HAL's first microprocessor and was the first in the SPARC64 brand. It operates at 101 and 118 MHz...
UNICOS is the name of a range of Unix-like operating system variants developed by Cray for its supercomputers. UNICOS is the successor of the Cray Operating System . It provides network clustering and source code compatibility layers for some other Unixes. UNICOS was originally introduced in 1985...
Many 64-bit compilers today use the LP64 model (including Solaris, AIX, HP-UX
HP-UX
HP-UX is Hewlett-Packard's proprietary implementation of the Unix operating system, based on UNIX System V and first released in 1984...
Mac OS X is a series of Unix-based operating systems and graphical user interfaces developed, marketed, and sold by Apple Inc. Since 2002, has been included with all new Macintosh computer systems...
FreeBSD is a free Unix-like operating system descended from AT&T UNIX via BSD UNIX. Although for legal reasons FreeBSD cannot be called “UNIX”, as the direct descendant of BSD UNIX , FreeBSD’s internals and system APIs are UNIX-compliant...
, and IBM z/OS native compilers). Microsoft's Visual C++
Visual C++
Microsoft Visual C++ is a commercial , integrated development environment product from Microsoft for the C, C++, and C++/CLI programming languages...
compiler uses the LLP64 model. The disadvantage of the LP64 model is that storing a long into an int may overflow. On the other hand, casting a pointer to a long will work. In the LLP model, the reverse is true. These are not problems which affect fully standard-compliant code, but code is often written with implicit assumptions about the widths of integer types.
Note that a programming model is a choice made on a per-compiler basis, and several can coexist on the same OS. However, the programming model chosen as the primary model for the OS API typically dominates.
Another consideration is the data model used for driver
Device driver
In computing, a device driver or software driver is a computer program allowing higher-level computer programs to interact with a hardware device....
s. Drivers make up the majority of the operating system code in most modern operating systems (although many may not be loaded when the operating system is running). Many drivers use pointers heavily to manipulate data, and in some cases have to load pointers of a certain size into the hardware they support for DMA
Direct memory access
Direct memory access is a feature of modern computers that allows certain hardware subsystems within the computer to access system memory independently of the central processing unit ....
. As an example, a driver for a 32-bit PCI device asking the device to DMA data into upper areas of a 64-bit machine's memory could not satisfy requests from the operating system to load data from the device to memory above the 4 gigabyte barrier, because the pointers for those addresses would not fit into the DMA registers of the device. This problem is solved by having the OS take the memory restrictions of the device into account when generating requests to drivers for DMA, or by using an IOMMU
IOMMU
In computing, an input/output memory management unit is a memory management unit that connects a DMA-capable I/O bus to the main memory...
.
Current 64-bit microprocessor architectures
64-bit microprocessor architectures for which processors are currently being manufactured include:
Advanced Micro Devices, Inc. or AMD is an American multinational semiconductor company based in Sunnyvale, California, that develops computer processors and related technologies for commercial and consumer markets...
to Intel's x86 architecture (later licensed by Intel); commonly known as "x86-64
X86-64
x86-64 is an extension of the x86 instruction set. It supports vastly larger virtual and physical address spaces than are possible on x86, thereby allowing programmers to conveniently work with much larger data sets. x86-64 also provides 64-bit general purpose registers and numerous other...
The Athlon 64 is an eighth-generation, AMD64-architecture microprocessor produced by AMD, released on September 23, 2003. It is the third processor to bear the name Athlon, and the immediate successor to the Athlon XP...
Opteron is AMD's x86 server and workstation processor line, and was the first processor which supported the AMD64 instruction set architecture . It was released on April 22, 2003 with the SledgeHammer core and was intended to compete in the server and workstation markets, particularly in the same...
Sempron has been the marketing name used by AMD for several different budget desktop CPUs, using several different technologies and CPU socket formats. The Sempron replaced the AMD Duron processor and competes against Intel's Celeron series of processors...
Phenom is the 64-bit AMD desktop processor line based on the K10 microarchitecture, in what AMD calls family 10h processors, sometimes incorrectly called "K10h". Triple-core versions belong to the Phenom 8000 series and quad cores to the AMD Phenom X4 9000 series...
Athlon II is a family of AMD multi-core 45 nm central processing units, which is aimed at the midrange to budget market and is a complementary product lineup to the Phenom II.-Features:...
Phenom II is a family of AMD's multi-core 45 nm processors using the AMD K10 microarchitecture, succeeding the original Phenom. Advanced Micro Devices released the Socket AM2+ version of Phenom II in December 2008, while Socket AM3 versions with DDR3 support, along with an initial batch of...
processors)
Intel's Intel 64 extensions (used in newer Celeron
Celeron
Celeron is a brand name given by Intel Corp. to a number of different x86 computer microprocessor models targeted at budget personal computers....
The original Pentium microprocessor was introduced on March 22, 1993. Its microarchitecture, deemed P5, was Intel's fifth-generation and first superscalar x86 microarchitecture. As a direct extension of the 80486 architecture, it included dual integer pipelines, a faster FPU, wider data bus,...
The Xeon is a brand of multiprocessing- or multi-socket-capable x86 microprocessors from Intel Corporation targeted at the non-consumer server, workstation and embedded system markets.-Overview:...
Yonah was the code name for Intel's first generation of 65 nm process mobile microprocessors, based on the Banias/Dothan-core Pentium M microarchitecture. SIMD performance has been improved through the addition of SSE3 instructions and improvements to SSE and SSE2 implementations, while integer...
Intel Atom is the brand name for a line of ultra-low-voltage x86 and x86-64 CPUs from Intel, designed in 45 nm CMOS and used mainly in netbooks, nettops, embedded application ranging from health care to advanced robotics and Mobile Internet devices...
VIA Technologies is a Taiwanese manufacturer of integrated circuits, mainly motherboard chipsets, CPUs, and memory, and is part of the Formosa Plastics Group. It is the world's largest independent manufacturer of motherboard chipsets...
The VIA Nano is a 64-bit CPU for personal computers. The VIA Nano was released by VIA Technologies in 2008 after five years of development by its CPU division, Centaur Technology...
Power Architecture is a broad term to describe similar RISC instruction sets for microprocessors developed and manufactured by such companies as IBM, Freescale, AMCC, Tundra and P.A. Semi...
The POWER6 is a microprocessor developed by IBM that implemented the Power ISA v.2.03. When it became available in systems in 2007, it succeeded the POWER5+ as IBM's flagship Power microprocessor...
POWER7 is a Power Architecture microprocessor released in 2010 that succeeded the POWER6. POWER7 was developed by IBM at several sites including IBM's Rochester, MN; Austin, TX; Essex Junction, Vermont; T. J. Watson Research Center, NY; Bromont, QC and Böblingen, Germany laboratories...
The PowerPC 970, PowerPC 970FX, PowerPC 970GX, and PowerPC 970MP, are 64-bit Power Architecture processors from IBM introduced in 2002. When used in Apple Inc. machines, they were dubbed the PowerPC G5....
The is the third home video game console produced by Sony Computer Entertainment and the successor to the PlayStation 2 as part of the PlayStation series. The PlayStation 3 competes with Microsoft's Xbox 360 and Nintendo's Wii as part of the seventh generation of video game consoles...
is a multinational electronics and electrical equipment corporation headquartered in Tokyo, Japan. It is a diversified manufacturer and marketer of electrical products, spanning information & communications equipment and systems, Internet-based solutions and services, electronic components and...
, commonly referred to as Sony, is a Japanese multinational conglomerate corporation headquartered in Minato, Tokyo, Japan and the world's fifth largest media conglomerate measured by revenues....
, combines a 64-bit Power architecture processor with seven or eight Synergistic Processing Elements.
Xenon is a CPU that is used in the Xbox 360 game console. The processor, internally codenamed "Waternoose", which was named after Henry J. Waternoose III in Monsters Inc. by IBM and XCPU by Microsoft, is based on IBM's PowerPC instruction set architecture, consisting of three independent processor...
Microsoft Corporation is an American public multinational corporation headquartered in Redmond, Washington, USA that develops, manufactures, licenses, and supports a wide range of products and services predominantly related to computing through its various product divisions...
The Xbox 360 is the second video game console produced by Microsoft and the successor to the Xbox. The Xbox 360 competes with Sony's PlayStation 3 and Nintendo's Wii as part of the seventh generation of video game consoles...
Sun Microsystems, Inc. was a company that sold :computers, computer components, :computer software, and :information technology services. Sun was founded on February 24, 1982...
The UltraSPARC is a microprocessor developed by Sun Microsystems who is now a part of Oracle Corporation and fabricated by Texas Instruments that implements the SPARC V9 instruction set architecture . It was introduced in mid-1995. It was the first microprocessor from Sun Microsystems to implement...
is a Japanese multinational information technology equipment and services company headquartered in Tokyo, Japan. It is the world's third-largest IT services provider measured by revenues....
SPARC64 is a microprocessor developed by HAL Computer Systems and fabricated by Fujitsu. It implements the SPARC V9 instruction set architecture , the first microprocessor to do so. SPARC64 was HAL's first microprocessor and was the first in the SPARC64 brand. It operates at 101 and 118 MHz...
z/Architecture, initially and briefly called ESA Modal Extensions , refers to IBM's 64-bit computing architecture for IBM mainframe computers. IBM introduced its first z/Architecture-based system, the zSeries Model 900, in late 2000. Later z/Architecture systems include the IBM z800, z990, z890,...
ESA/390 was introduced in September 1990 and is IBM's last 31-bit-address/32-bit-data mainframe computing design, copied by Amdahl, Hitachi, and Fujitsu among other competitors...
architecture, used in IBM's eServer zSeries and System z mainframes
Itanium is a family of 64-bit Intel microprocessors that implement the Intel Itanium architecture . Intel markets the processors for enterprise servers and high-performance computing systems...
MIPS Technologies, Inc. , formerly MIPS Computer Systems, Inc., is most widely known for developing the MIPS architecture and a series of pioneering RISC chips. MIPS provides processor architectures and cores for digital home, networking and mobile applications.MIPS Computer Systems Inc. was...
MIPS is a reduced instruction set computer instruction set architecture developed by MIPS Technologies . The early MIPS architectures were 32-bit, and later versions were 64-bit...
Most 64-bit processor architectures that are derived from 32-bit processor architectures can execute code for the 32-bit version of the architecture natively without any performance penalty. This kind of support is commonly called bi-arch support or more generally multi-arch support.
Images
In digital imaging, 64-bit refers to 48-bit images with a 16-bit
16-bit
-16-bit architecture:The HP BPC, introduced in 1975, was the world's first 16-bit microprocessor. Prominent 16-bit processors include the PDP-11, Intel 8086, Intel 80286 and the WDC 65C816. The Intel 8088 was program-compatible with the Intel 8086, and was 16-bit in that its registers were 16...
In computer graphics, alpha compositing is the process of combining an image with a background to create the appearance of partial or full transparency. It is often useful to render image elements in separate passes, and then combine the resulting multiple 2D images into a single, final image in a...
