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Intel 8008
The Intel 8008 was an early microprocessor designed and manufactured by Intel and introduced in April, 1972. The 8008 was originally codenamed the 1201. It was originally commissioned by Computer Terminal Corporation for use in its Datapoint 2200 programmable terminal, but because the chip was delivered late and did not meet CTC's performance goals, the chip was not used in the 2200. An agreement between Intel and CTC permitted Intel to market the chip to other customers.
The instruction set of the 8008 and subsequent Intel CISC CPUs were heavily based on CTC's design.
The chip (limited by its 18 pin DIP packaging) had a single 8-bit bus and required a very large amount of external logic to support it. For example, the 14-bit address, which could access 16K bytes of memory, needed to be latched by some of this logic in an external Memory Address Register (MAR). It could access 8 input ports and 24 output ports.
While a little slower in terms of instructions per second than the 4-bit Intel 4004 and Intel 4040, the fact that the 8008 processed data eight bits at a time and could access significantly more RAM actually gave it 3 to 4 times the true processing power of the 4-bit chips.
For controller and CRT terminal use this was an acceptable design, but it was too difficult to use for most other tasks. A few early computer designs were based on it, but most would use the later and greatly improved Intel 8080 instead.
The 8008 family is also referred to as the MCS-8.
Designers
Ted Hoff, Stan Mazor, Hal Feeney, Federico Faggin
External links
- [http://www.eee.bham.ac.uk/woolleysi/teaching/microhistory.htm A Brief History of Microprocessors]
Category:Microprocessors
ja:Intel 8008
IntelThe following article is about the multinational corporation; intel is also an abbreviation for intelligence, used in reference to military intelligence and espionage.
Intel Corporation (, ), founded 1968, is a U.S.-based multinational corporation that is best known for designing and manufacturing microprocessors and specialized integrated circuits. Intel also makes network cards, motherboard chipsets, components, and other devices. Intel has advanced research projects in all aspects of semiconductor manufacturing, including MEMS.
Overview
Intel was founded in 1968 by Gordon E. Moore (a chemist and physicist) and Robert Noyce (a physicist and co-inventor of the integrated circuit) when they left Fairchild Semiconductor. It is noteworthy that Intel competitor AMD was also founded by the Traitorous Eight, in 1969. Intel's employee number four was Andy Grove (a chemical engineer), who ran the company through much of the 1980s and the high-growth 1990s. It is Grove who is now remembered as the company's key leader. By the end of the 1990s, Intel was one of the largest and most successful businesses in the world, though fierce competition within the semiconductor industry has since diminished its position somewhat.
SRAMS and the microprocessor
1990s
The company's first products were random-access memory integrated circuits, and Intel grew to be a leader in the fiercely competitive DRAM, SRAM, and ROM markets throughout the 1970s. Concurrently, Intel engineers Marcian Hoff, Federico Faggin, Stanley Mazor and Masatoshi Shima invented the first microprocessor. Originally developed for the Japanese company Busicom to replace a number of ASIC's in a calculator already produced by Busicom, the Intel 4004 was introduced to the mass market on November 15, 1971, though the microprocessor did not become the core of Intel's business until the mid-1980s. (Note: Intel is usually given credit with Texas Instruments for the almost-simultaneous invention of the microprocessor.)
From DRAM to microprocessors
In 1983 at the dawn of the personal computer era, Intel's profits came under increased pressure from Japanese memory-chip manufacturers, and then-President Andy Grove drove the company into a focus on microprocessors. Grove described this transition in the book Only the Paranoid Survive. A key element of his plan was the notion, then considered radical, of becoming the single source for successors to the popular 8086 microprocessor.
Until then, manufacture of complex integrated circuits was not reliable enough for customers to depend on a single supplier, but Grove began producing processors in three geographically distinct factories, and ceased licensing the chip designs to competitors such as Zilog and AMD. When the PC industry exploded in the late 1980s and 1990s, Intel was one of the primary beneficiaries.
The rise of PC architecture
AMD
During the 1990s, Intel's Intel Architecture Labs (IAL) was responsible for many of the hardware innovations of the personal computer, including the PCI Bus, the PCI Express (PCIe) bus, the Universal Serial Bus (USB), and the now-dominant architecture for multiprocessor servers. IAL's software efforts met with a more mixed fate; its video and graphics software was important in the development of software digital video, but later its efforts were largely overshadowed by competition from Microsoft. The competition between Intel and Microsoft was revealed in testimony at the Microsoft antitrust trial.
Partnership with Apple
On June 6 2005, Apple Computer CEO Steve Jobs announced in his keynote address at WWDC that Apple would be transitioning from its long-favored PowerPC Architecture to Intel CPUs. Reasons stated for the change were vague, but included thermal issues, as recent G5-class PowerPC chips are well-known for running hot. Also, it was implied that the future PowerPC roadmap was unable to satisfy Apple's needs in terms of computing power. In particular, the large power requirement of the G5 chips was seen as a major stumbling block, preventing the placement of such a chip in one of Apple's laptop computers, the PowerBook and iBook. The switchover to Intel will begin in mid-2006, reportedly appearing first in Apple's low-end machines and portables.
Competition and antitrust
Intel's dominance in the x86 microprocessor market led to numerous charges of antitrust violations over the years, including FTC investigations in both the late 1980s and in 1999, and civil actions such as the 1997 suit by Digital Equipment Corporation (DEC) and a patent suit by Intergraph. Intel's market dominance (at one time it controlled over 85% of the market for 32-bit PC microprocessors) combined with Intel's own hardball legal tactics (such as its infamous 338 patent suit versus PC manufacturers) made it an attractive target for litigation, but few of the lawsuits ever amounted to anything.
Currently, the only major competitor to Intel on the x86 processor market is Advanced Micro Devices (AMD), with which Intel has had full cross-licensing agreements since 1976: each partner can use the other's patented technological innovations without charge. Some smaller competitors such as Transmeta produce low-power processors for portable equipment.
In June 2005, AMD sued Intel in two jurisdictions for anticompetitive practices. The Japanese Fair Trade Commission found in favor of AMD; the other case will be heard by a court in Delaware. The case in Japan led to "dawn raids" by the European Commission on some European Intel offices in July 2005.
Intel filed its response[http://www.intel.com/pressroom/archive/releases/20050901corp.htm] in September to AMD's lawsuit and refuted AMD's claims, stating that its business practices are fair and lawful. In its rebuttal, Intel laid out the skeleton of its legal defense, which included a deconstruction of AMD's offensive strategy and levied the charge that AMD's long-struggling market position is largely a result of bad business decisions and management incompetence, including underinvestment in essential manufacturing capacity and overreliance on outsourcing chip foundries.[http://www.forbes.com/technology/2005/09/02/intel-amd-antitrust-cz_dw_0902intel.html?partner=yahootix]
Legal experts predict the lawsuit will most likely drag out for a number of years, since Intel's response indicates they are not likely to try and settle with AMD.
Leadership
Robert Noyce was Intel's CEO at its founding in 1969, followed by co-founder Gordon Moore in 1975. Andy Grove became the company's President in 1979 to which he added the CEO title in 1987 when Moore became Chairman. In 1997 Grove succeeded Moore as Chairman, and Craig Barrett, already company president, took over. On May 18 2005, Barrett handed the reins of the company over to Paul Otellini, who previously was the company president and was responsible for Intel's design win in the original IBM PC. The board of directors elected Otellini, and Barrett replaced Grove as chairman of the board. Grove stepped down as Chairman, but will be retained as a special advisor.
Corporate governance
Current members of the board of directors of Intel are: Craig Barrett, Charlene Barshefsky, John Browne, James Guzy, Reed Hundt, James Plummer, David Pottruck, Jane Shaw, John Thornton, and David Yoffie.
Origin of the name
At its founding, Gordon Moore and Robert Noyce wanted to name their new company "Moore Noyce". But the name did not sound good in electronics—noise being associated with bad interference. They then used the name NM Electronics for almost a year, before deciding to call their company INTegrated ELectronics or "Intel" for short. However, Intel was already trademarked by a hotel chain, so they had to buy the rights for that name at the beginning.
Financial information
Its market capitalization is about $154 billion (March 2005).
Stock exchanges
- Intel is publicly traded at NASDAQ with the symbol INTC.
Indices
- Dow Industrials
- S&P 500
- Nasdaq 100
- SOX (PHLX Semiconductor Sector)
- GSTI Software Index
Diversity
Intel received a 100% rating on the first Corporate Equality Index released by the Human Rights Campaign in 2002. It has maintained this rating in 2003 and 2004. In addition, the company was named one of the 100 Best Companies for Working Mothers in 2005 by Working Mother magazine. However, Intel's working practices still face criticism, most notably from Ken Hamidi, a former employee who has been subject to multiple unsuccessful lawsuits from Intel. [http://www.faceintel.com/]
Controversial issues
Antitrust claims
In June 2005, AMD, Intel's chief rival in the x86 microprocessor market, filed an antitrust claim against Intel and its Japanese subsidiary in a Delaware court. Amongst other accusations, AMD alleged that Intel was unlawfully maintaining its monopoly through unfair business practices, such as drastically lower pricing for customers on the condition that Intel microprocessors were used exclusively in their systems. Whilst proving that Intel holds a monopoly is simple (the company is reckoned to have an 80%–90% share of the processor market), the debate over the "scare and coercion" tactics supposedly employed by Intel is likely to be more protracted. IT insiders foresee the case to be a landmark ruling in what is a fiercely competitive market.
Advertising
Intel has become one of the world's most recognizable brands following its long-running "Intel Inside" campaign. The campaign, which started in 1990, was created by Intel marketing manager Dennis Carter. The five-note jingle was introduced the following year and by its tenth anniversary was being heard in 130 countries around the world.
The Intel Inside program is very lucrative for advertisers. Intel pays half the advertising costs for any ad that uses the "Intel Inside" logo. However, if in print, the ad page cannot contain any references to competitors, such as AMD. If the ads do not meet these requirements, Intel does not pay half the cost and the advertiser is prohibited from using the "Intel Inside" logo. Intel employs a large staff whose primary function is looking for advertisements which violate the agreement. Advertisers found doing so—many of which are "mom and pop" shops ignorant of the reimbursement agreement—are requested to stop violating the use of the logo and are then told how to legally use the logo and get part of their advertising costs reimbursed.
The Centrino advertising campaign has been hugely successful, leading to the ability to acess wireless internet from a laptop becoming linked in consumers minds to intel chips. In the UK this has caused some controversy, as the ASA upheld complaints that this was a misleading advert.
PC companies advertising products containing Intel chips are required to include the jingle in their film and television adverts in order to receive the reimbursement.
See also
- List of Intel microprocessors
- List of Intel chipsets
External links
- [http://www.intel.com/ Intel website]
- [http://www.intel.com/intel/finance/ Intel Investor Relations site]
- [http://www.intel.com/intel/intelis/museum/ Intel Museum]
- [http://www.amdboard.com/pintospecial.html Intel vs. AMD saga]
- [http://www.inteltechnology.net/ Intel Technology]
Data
- [http://biz.yahoo.com/ic/13/13787.html Yahoo! - Intel Corporation Company Profile]
Category:Electronics companies
Category:Computer companies of the United States
Category:Computer hardware companies
Category:Electronics companies of the United States
Category:Manufacturing companies of the United States
Category:Fortune 500 companies
Category:Companies traded on NASDAQ
Category:Companies based in California
Category:Companies based in Oregon
ko:인텔
ja:インテル (企業)
th:อินเทล
Computer Terminal CorporationDatapoint Corporation, originally known as Computer Terminal Corporation (CTC), was a computer company based in San Antonio, Texas. Founded in 1967 by Phil Ray and Gus Roche, its first products were, as the company's initial name suggests, computer terminals (intended to replace teletype units connected to time sharing systems). In October 1969, the company raised US$4 million through an Initial Public Offering (IPO).
Early years; CTC's role in computer history
CTC is credited by some historians with accidentally inventing the personal computer. Its most popular product, the Datapoint 2200, was a programmable terminal that could load various emulations stored on cassette tapes. Some users of the terminals chose to use them as simple programmable computers instead.
The Datapoint 2200 also led to the development of the first 8-bit microprocessors, as CTC did not believe it could meet its design goals by using a CPU built from discrete TTL chips. CTC approached Intel and Texas Instruments, neither of whom could meet CTC's deadlines. Consequently, the 2200 was released using the conventional SSI/MSI chip technology of the time. Turning out to be of great historical significance, however, CTC's specifications led to the creation of the Intel 8008 single chip microprocessor. Thus, today's overwhelmingly dominant instruction set architecture, used in Intel's x86 family of processors as well as all compatible CPUs from AMD and others, traces its ancestry directly back to CTC.
The Datapoint 2200 became so popular that CTC later changed its name to Datapoint Corp. Other Datapoint inventions were ARCnet, invented in 1977, which was an early local area network (LAN) protocol, and the PL/B high-level programming language, which was originally called Databus (from Datapoint business language).
Heyday and decline
By the early 1980s, Datapoint was a Fortune 500 company. Under immense pressure to increase sales figures, its sales representatives encouraged customers to place large orders at the end of the fiscal year, permitting the company to count the orders as revenue even though the money had not been received and, in some instances, the sold equipment had not yet even been produced.
When some of the customers went broke before paying their bills, Datapoint had to reverse sales or record substantial bad debts, which caused the company to lose $800 million of its market capitalization in a matter of a few months in early 1982. The U.S. Securities and Exchange Commission (SEC) ordered Datapoint to stop this practice.
Demise and divestiture
Taken over by corporate raider Asher Edelman in 1985, Datapoint spun off its services division into another company, named Intelogic Trace, Inc. that same year. Initially Intelogic Trace specialized in servicing Datapoint equipment but later broadened into supporting products from other vendors as well. But Intelogic Trace, too, soon ran into trouble, declared Chapter 11 bankruptcy, and on April 6, 1995, its assets were sold to a company in Pennsylvania.
Datapoint itself weathered a subsequent battle for control of the company that triggered more attention from the SEC, and although it launched new products, it never regained its former innovativity and prominence.
On May 3, 2000, Datapoint filed for Chapter 11 bankruptcy and on June 19, 2000 sold the Datapoint name and various operations to its European subsidiary for $49.3 million. The now fully European Datapoint company changed its emphasis to call center equipment and largely pulled out of the computer market. Headquartered in Brentford, England, it also has offices Manchester, England, and Madrid, Spain.
Also on June 19, 2000, the remnant of Datapoint's US operations changed its name to Dynacore Holdings Corporation and formed a subsidiary that pursued 14 lawsuits based on two patents granted to Datapoint regarding local area networks. With only $1.3 million left from the sale of its European operations after paying its debts and no products left to sell—its total revenues for the first half of 2001 dwindled to $9,000 and a year later fell to nothing—Dynacore searched for a company to buy. In February 2003, Dynacore engaged in a reverse takeover of The CattleSale Company. Asher Edelman now sits in CattleSale's board of directors.
An office building and street in San Antonio still bear Datapoint's name.
External links
- [http://www.datapoint.com Homepage of Datapoint, the UK-based call center company]
- [http://www.cattlesale.com Homepage of The CattleSale Company ]
Category:Defunct computer companies of the United States
Category:Telecommunication companies of the United Kingdom
Then boobs took over the world.
CISCA Complex Instruction Set Computer (CISC) is a microprocessor instruction set architecture (ISA) in which each instruction can execute several low-level operations, such as a load from memory, an arithmetic operation, and a memory store, all in a single instruction. The term was coined in contrast to Reduced Instruction Set Computer (RISC).
Before the first RISC processors were designed, many computer architects tried to bridge the "semantic gap" - to design instruction sets to support high-level programming languages by providing "high-level" instructions such as procedure call and return, loop instructions such as "decrement and branch if non-zero" and complex addressing modes to allow data structure and array accesses to be combined into single instructions. Additionally, the compact nature of a CISC ISA results in program sizes and fewer calls to main memory, which at the time (the 1960s) resulted in a tremendous savings on the cost of a computer.
While they achieved their aim of allowing high-level language constructs to be expressed in fewer instructions, it was observed that they did not always result in improved performance. For example, on one processor it was discovered that it was possible to improve performance by not using the procedure call instruction but using a sequence of simpler instructions instead. Furthermore, the more complex the instruction set, the greater the overhead of decoding any given instruction, both in execution time and silicon area. This is particularly true for processors which used microcode to decode the (macro)instructions. In other words, adding a large and complex instruction set to the processor even slowed down the execution of simple instructions. Implementing all these complex instructions also required a lot of work on the part of the chip designer, and a lot of transistors; this left less room on the processor to optimize performance in other ways.
Examples of CISC processors are the VAX, PDP-11, Motorola 68000 family and the Intel x86 CPUs.
The term, like its antonym RISC, has become less meaningful with the continued evolution of both CISC and RISC designs and implementations. Modern "CISC" CPUs, such as recent x86 designs like the Pentium 4, whilst they usually support every instruction that their predecessors did, are designed to work most efficiently with a subset of instructions more resembling a typical "RISC" instruction set. Indeed, many CISC CPUs (such as modern x86 processors from both Intel and AMD) decode many x86 instructions into a series of smaller internal "micro-operations" that are then executed internally by the processor.
See also
- CPU
- RISC
- ZISC
- microprocessor
- computer
- CPU design
- computer architecture
Category:Computer architecture
ko:CISC
ja:CISC
Dual in-line package
pl:Dual in-line package
pl:Dual in-line package
In microelectronics, a dual in-line package (DIP), sometimes called a DIL package, is an electronic device package with a rectangular housing and a row of electrical connecting pins along each of two opposite sides, usually the longer sides of the rectangle. A DIP is usually referred to as a DIPn, where n is the total number of pins).
DIPs may be used for integrated circuits (ICs, "chips"), like microprocessors, or for discrete components such as resistors or toggle switches. A typical DIP may be a microcircuit package with two rows of seven vertical leads (i.e., a DIP14) that is specially designed for mounting on a printed circuit board (PCB).
JEDEC-standard DIPs have the inter-lead spacing (lead pitch) specified as 0.1" (2.54 mm) and the row spacing is specified at 0.3" (7.62 mm).
Several DIP variants exist, mostly distinguished by packaging material:
- Ceramic Dual In-line Package (CERDIP)
- Plastic Dual In-line Package (PDIP)
- Shrink Plastic Dual In-line Package (SPDIP) – A shrink version of the PDIP with a 0.07" (1.778 mm) lead pitch
DIPs were the mainstream of the microelectronics industry in the 1970s and 80s. Their use has subsided in recent years due to the emerging new surface-mount technology (SMT) packages such as pin grid arrays (PGAs) and ball grid arrays (BGAs).
Sources
- Federal Standard 1037C
- Intel (1996). Packaging (databook). ISBN 1-55512-254-X.
Category:Chip carriers
Million Instructions Per SecondInstructions per second (IPS) is a measure of a computer's processor speed. Many reported IPS values have represented "peak" execution rates on artificial instruction sequences with few branches, whereas realistic workloads consist of a mix of instructions and even applications, some of which take longer to execute than others. The performance of the memory hierarchy also greatly affects processor performance, an issue barely considered in MIPS calculations. Because of these problems, researchers created standardized tests such as SPECint to (maybe) measure the real effective performance in commonly used applications, and raw IPS has fallen into disuse.
The term is commonly used in association with a numeric value such as thousand instructions per second (kIPS) or million instructions per second (MIPS).
Thousand instructions per second
A thousand instructions per second (kIPS) is rarely used, as most current microprocessors can execute several million instructions per second. The thousand means 1000 not 1024.
kIPS is also a common joke name for 16 bit microprocessor designs developed in undergraduate computer engineering courses that use the text Computer Organization and Design by Patterson and Hennessy (ISBN 1-55860-428-6), which explains computer architecture concepts in terms of the MIPS architecture. Such architectures tend to be scaled down versions of the MIPS R2000 architecture.
Million instructions per second
Critics of the term refer to it as "Meaningless Indication of Processor Speed" or "Meaningless Information on Performance for Salespeople." In Linux and UNIX circles MIPS are often referred to as bogoMIPS. MIPS are certainly not comparable between CPU architectures.
The floating-point arithmetic equivalent of MIPS is FLOPS, to which the same cautions apply.
In the 1970s, minicomputer performance was compared using VAX MIPS, where computers were measured on a task and their performance rated against the VAX 11/780 that was marketed as a "1 MIPS" machine. (The measure was also known as the "VAX Unit of Performance" or VUP.)
Most 8-bit and early 16-bit microprocessors have a performance measured in KIPS (thousand instructions per second), which equals 0.001 MIPS.
The first general purpose microprocessor, the Intel i8080, ran at 640 KIPS.
The Intel i8086 microprocessor, the first 16-bit microprocessor in the line of processors made by Intel and used in IBM PCs, ran at 800 KIPS. Early 32-bit PCs (386) ran at about 3 MIPS.
zMIPS refers to the MIPS measure used internally by IBM to rate its mainframe servers (zSeries and System z9). Analyst firm [http://www.isham-research.co.uk Isham Research] has lately coined the term kMIPS (kilo-million instructions per second) to measure the processor speeds in IBM's largest servers.
Timeline of instructions per second
New DHRYSTONE 2.1 MIPS Benchmark with Optimisation, can you found [http://homepage.virgin.net/roy.longbottom/dostests.zip here] (DHRY2OD.EXE)
See also
- benchmark (computing)
- million service units (MSU)
- Peak MIPS
- Relative MIPS
- [http://amigator.free.fr/Atrucs/proces.htm list on différents MIPS by Amiga processeurs]
Category:Units of measure
ja:MIPS
Intel 4004
The Intel 4004, a 4-bit central processing unit (CPU) released by Intel Corp. in 1971, is widely considered to be the world's first commercial single-chip microprocessor.
Although originally designed to be a component in an Intel customer's calculator products, the 4004 soon found many uses as a flexible replacement for collections of simple logic chips in a variety of applications, thus indicating that there existed an untapped market for microprocessors as such. This prompted Intel and some other integrated circuit manufacturers to embark on a path of developing steadily more capable microprocessors—a trend that eventually created the multibillion-dollar microprocessor and microcomputer industries of today.
History and description
The 4004 was released in 16-pin CERDIP packaging on November 15th, 1971. The 4004 is the first computer processor designed and manufactured by chip maker Intel, which previously made semiconductor memory chips. The chief designers of the chip were Ted Hoff and Federico Faggin of Intel and Masatoshi Shima of Busicom (later of ZiLOG).
Originally designed for the Japanese company Busicom to be used in their line of calculators, the 4004 was also provided with a family of custom support chips (e.g., each "Program ROM" internally latched for its own use the 4004's 12-bit program address, which allowed 4 KB memory access from the 4-bit address bus if all 16 ROMs were installed). The 4004 circuit was built of 2,300 transistors, and was followed the next year by the first ever 8-bit microprocessor, the 3,300 transistor 8008 (and the 4040, a revised 4004).
As its fourth entry in the microprocessor market, Intel released the CPU that started the microcomputer revolution — the 8080.
Technical specifications
- Maximum clock speed is 740 kHz
- Separate program and data storage (i.e., a Harvard architecture). Contrary to most Harvard architecture designs, however, which use separate buses, the 4004, with its need to keep pin count down, uses a single multiplexed 4-bit bus for transferring:
- 12-bit addresses
- 8-bit instructions, not to be placed in the same memory as
- 4-bit data words
- Instruction set contains 46 instructions (of which 41 are 8 bits wide and 5 are 16 bits wide)
- Register set contains 16 registers of 4 bits each
- Internal subroutine stack is 3 levels deep
Microarchitecture and pinout
Click the pictures to view the full-size versions.
Custom support chips
- 4001: 256-byte ROM (256 8-bit program instructions), and one built-in 4-bit I/O port
-
- 4002: 40-byte RAM (80 4-bit data words), and one built-in 4-bit output port; the RAM portion of the chip is organized into four "registers" of twenty 4-bit words:
- 16 data words (used for mantissa digits in the original calculator design)
- 4 status words (used for exponent digits and signs in the original calculator design)
- 4003: 10-bit parallel output shift register for scanning keyboards, displays, printers, etc.
- 4008: 8-bit address latch for access to standard memory chips, and one built-in 4-bit chip select and I/O port
-
- 4009: program and I/O access converter to standard memory and I/O chips
-
(
- ) Note: a 4001 ROM+I/O chip cannot be used in a system along with a 4008/4009 pair.
Collectability
The Intel 4004, naturally, is one of world's most sought-after collectable/antique chips. Of highest value are 4004's that are gold and white, with visible so called 'grey traces' on the white portion (the original package type). As of 2004, such chips reached around US$400 each on eBay. The slightly less valuable white and gold chips without grey traces typically reach $200 to $300. Those chips without a 'date code' underneath are earlier versions, and therefore worth slightly more. Other valuable chips include the Intel 4040.
Notes
# In 1970, over a year prior to the introduction of the 4004, the single-chip military F14 CADC microprocessor was deployed, though its existence remained classified until 1998.
External links
- [http://www.intel4004.com/ The Intel 4004: A testimonial from Federico Faggin, its designer, on the first microprocessor's thirtieth birthday] – Faggin's own 4004 website
- [http://www.ieee.org/organizations/history_center/oral_histories/transcripts/shima.html Interview with Masatoshi Shima regarding his role in the 4004] – At the IEEE's History Center pages
- [http://smithsonianchips.si.edu/ice/4004thb.htm MCS-4 Micro Computer Set Data Sheet (12 pp.)] – Intel Corp., November 1971; At the Smithsonian's Chip Collection website
- [http://www.cpu-museum.com/4004_e.htm Comprehensive Intel 4004 chipset information] – At Christian Bassow's CPU Museum
- [http://www.antiquetech.com/chips/4004.htm Intel 4004 chip collecting information] – At The Antique Chip Collector's Page
Category:Microprocessors
ja:Intel 4004
Cathode ray tube
The cathode ray tube or CRT, invented by Karl Ferdinand Braun, is the display device that was traditionally used in most computer displays, video monitors, televisions and oscilloscopes. The CRT developed from Philo Farnsworth's work was used in all television sets until the late 20th century and the advent of plasma screens, LCDs, DLP, OLED displays, and other technologies. As a result of this technology, television continues to be referred to as "The Tube" well into the 21st century, even when referring to non-CRT sets.
Apparatus description
The earliest version of the CRT was a cold-cathode diode, a modification of the Crookes tube with a phosphor-coated screen, sometimes called a Braun tube. The first version to use a hot cathode was developed by J. B. Johnson (who gave his name to the term Johnson noise) and H. W. Weinhart of Western Electric and became a commercial product in 1922.
Cathode rays exist in the form of streams of high speed electrons emitted from the heating of cathode inside a vacuum tube.
The released electrons form a beam within the cathode ray tube due to the voltage difference applied in the two electrodes, and the direction of this beam is then altered either by a magnetic or electric field to swap over the surface at the fluorescent screen (anode), covered by phosphorescent material (often transition metals or rare earths). Light is emitted at the instant that electrons hit the surface of that material.
In case of a television and modern computer monitors, the entire front area of the tube is scanned in a fixed pattern called a raster, and a picture is created by modulating the intensity of the electron beam according to the programme's video signal. The beam in all modern TV sets is scanned with a magnetic field applied to the neck of the tube with a "magnetic yoke", a set of coils driven by electronic circuits. This usage of electromagnets to change the electron beam's original direction is known to be "magnetic deflection".
In case of an oscilloscope, the intensity of the electron beam is kept constant, and the picture is drawn by steering the beam along an arbitrary path. Usually, the horizontal deflection is proportional to time, and the vertical deflection is proportional to the signal. The tube for this kind of use is longer and narrower, and deflection is done by applying an electrical field via deflection plates built into the tube's neck. The use of an electrical field (so-called "electrostatic deflection") allows the electron beam to be steered much more rapidly than with a magnetic field, where the inductance of the electromagnets imposes relatively severe limits on the frequency range that can be accurately reproduced.
The electron beam source is the electron gun, producing the stream of electrons by thermionic emission and then focusing it to a thin beam. The gun was often mounted slightly off-axis, as it accelerated not only electrons but also ions resulting from outgassing of the internal tube components and from an imperfect vacuum. The ions are heavier than electrons, therefore they are less likely to be deflected by the magnetic field from the deflection coils, and in older constructions with in-axis guns they were bombarding the phosphor in the center of the screen and causing its deterioration; some very old black and white TV sets show browning of the center of the screen, known as ion burn. The combination of an off-axis mounting of electron guns and permanent magnets bending the electron beam back in the desired direction forms an ion trap; the ions were not deflected enough so they struck the neck of the tube instead of the screen and harmlessly dissipated. This system was later replaced with aluminium coating of the phosphor.
The internal side of the phosphor layer is often covered with a layer of aluminium. The phosphors are usually poor electrical conductors, which leads to deposition of residual charge on the screen, effectively decreasing the energy of the impacting electrons due to electrostatic repulsion (an effect known as "sticking"). The aluminium layer is connected to the conductive layer inside the tube, disposing of this charge. It also reflect the phosphor light in the desired direction towards the viewer, and protects the phosphor from ion bombardment.
aluminium
Graphical displays for early computers used vector monitors, a type of CRT similar to the oscilloscope. Here, the beam would trace straight lines between arbitrary points, repeatedly refreshing the display as quickly as possible. Vector monitors were used in many computer displays as well as by some late 1970s to mid 1980s arcade games such as Asteroids. Vector displays for computers did not noticeably suffer the display artifacts of aliasing and pixelization, but were limited in that they could display only a shape's outline, and only a very small amount of rather largely-drawn text. (Because the speed of refresh was roughly inversely proportional to how many vectors needed to be drawn, "filling" an area using many individual vectors was impractical as was the display of a large amount of text.) Some vector monitors are capable of displaying several colors using either an ordinary tri-color CRT or two phosphor layers (so called "penetration color"). In these dual-layer tubes, by controlling the strength of the electron beam, electrons could be made to reach (and illuminate) either or both phosphor layers, typically producing green, orange, or red.
Other graphical displays used storage tubes including Direct View Bistable Storage Tubes (DVBSTs). These CRTs inherently stored the image and did not require periodic refreshing.
Some displays for early computers (those that needed to display more text than was practical using vectors, or required high speed for photographic output) used Charactron CRTs. These used a perforated metal character mask ("Stencil") to shape a wide electron beam to form a selected character shape on the screen. The electronics could quickly select a character on the mask with one set of deflection circuits, while selecting the position to display the character at with a second set of deflection circuits, and then just turn on the beam briefly to draw that character. Graphics could still be drawn by selecting the unneeded position on the mask corresponding to the code for a space (when drawing a space the beam was simply kept off), which had a small round hole in the center instead of being solid, and draw this as with other displays.
Many of these various types of early computer display CRTs use "slow" or long persistance phosphor, to reduce flicker for the operator.
Stencil
Stencil
Color tubes use three different materials which specifically emit red, green, and blue light, closely packed together in strips (in aperture grille designs) or clusters (in shadow mask CRTs). There are three electron guns, one for each color, and each gun can reach only the dots of one color, as the grille or mask absorbs electrons that would otherwise hit the wrong phosphor.
The outer glass allows the light generated by the phosphor out of the monitor, but (for color tubes) it must block dangerous X-rays generated by the impact of the high energy electron beam. For this reason, the glass is made of leaded glass (sometimes called "lead crystal"). Because of this and other shielding, and protective circuits designed to prevent the anode voltage rising too high, the X-ray emission of modern CRTs is well within safety limits.
CRTs have a pronounced triode characteristic, which results in significant gamma (a nonlinear relationship between beam current and light intensity). In early televisions, screen gamma was an advantage because it acted to compress the screen contrast. The gamma characteristic exists today in all digital video systems. However, in some systems where a linear response is required, as in desktop publishing, gamma correction is applied.
CRT displays accumulate static electrical charge on the screen, unless protective measures are taken. This charge does not pose a safety hazard, but can lead to significant degradation of image quality through attraction of dust particles to the surface of the screen. Unless the display is regularly cleaned with a dry cloth or special cleaning tissue (using ordinary household cleaners may damage anti-glare protective layer on the screen), after a few months the brightness and clarity of the image drops significantly.
Other technologies
It is likely that technologies such as plasma displays, liquid crystal displays, and other newer technologies will eventually make CRT-based displays mostly obsolete, because the new designs are less bulky and consume less power. As of mid-2003, LCDs are becoming directly comparable in price to CRTs, with LCDs forming 30% of the computer display market by value. However, color CRTs still find adherents in computer gaming, due to their very quick response time, and in the printing and TV broadcasting industries for their better color fidelity and contrast.
Magnets
Magnets should never be put next to a color CRT, as they may cause magnetization of the shadow mask, which will cause incorrect colors to appear in the magnetized area and may be expensive to have corrected. Most modern television sets and nearly all newer computer monitors have a built-in degaussing coil. This coil creates a brief, alternating magnetic field from standard 50 or 60 Hz household power upon power-up which decays in strength as a resistor in the circuit increases resistance with its increasing temperature as a result of the current passing through it. The alternating magnetic field created is sufficient enough to shake off most cases of shadow mask magnetization. It is also possible to purchase or to build your own external degaussing coil which can aid in demagnetizing older sets or in cases where the built-in coil was not effective. A soldering gun (a soldering iron will not work as it does not contain a large transformer which produces a large alternating magnetic field) may also be used to degauss a monitor by holding it up to the center of the monitor with the hot tip end facing safely AWAY from the glass (and yourself!) and while holding down the on button, slowly moving the gun in ever wider concentric circles past the edge of the monitor until the shimmering colors can no longer be seen. This may need to be repeated several times to remove severe magnetization.
In extreme cases, high power magnets such as the now popular neodymium iron boron, or NIB magnets, can actually deform the shadow mask. This type of damage is considered permanent and will render the CRT mostly useless. However, subjecting an old black and white television or monochrome (green screen, amber screen) computer monitor to magnets is generally harmless. This can be used as a demonstration tool and children should even be encouraged to do this so that they may see the immediate and dramatic effect of a magnetic field on moving charged particles, provided they are informed to never do the same with a color tube.
Health danger
Some believe the electromagnetic fields emitted by CRT monitors constitute a health danger to the functioning of living cells. Exposure to these fields is far lower at distances of 85 cm or farther. It is also less intensive for the display's user than for a person located behind it.
CRTs also emit very small amounts of X-rays as a result of the electron beam's bombardment of the shadow mask/aperture grille and phosphors. Almost all of this radiation is blocked by the thick leaded glass in the screen so the amount of radiation escaping the front of the monitor is mostly harmless. The Food and Drug Administration regulations in 21 CFR 1020 are used to strictly limit, for instance, television receivers to 0.5 milliroentgens per hour (mR/h) (0.13 µC/(kg·h) (at a distance of 5 cm from any external surface and as mentioned above, most CRT emissions fall well below this limit.[http://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfcfr/CFRSearch.cfm?fr=1020.10]
Old CRTs may also have used toxic phosphors, although that is much less common today. An implosion or other breaking of the glass envelope could release these toxic phosphors. And because of the X-ray hazard, the glass envelopes of most modern CRTs are made from heavily leaded glass. The lead in this glass may represent an environmental hazard, especially in the presence of acid rain leaching through landfills.
The constant refreshing of a CRT can cause seizures in epileptics, if they are photosensitive. Filters are available to reduce these effects.
A high refresh rate (above 75 Hz) also helps to negate these effects.
CRTs operate at very high voltages. These voltages can persist long (several days) after the device containing the CRT has been switched off and unplugged. (Modern circuits contain bleeder resistors to ensure the high-voltage supply is discharged to safe levels within a couple of minutes at most.)
Do not tamper with devices containing CRT tubes unless you have proper engineering training and have taken appropriate precautions. Since the CRT contains a vacuum, care should be taken to prevent implosion.
High vacuum safety
Because CRTs "contain" a strong vacuum, they store a large amount of mechanical energy; they can implode very forcefully if the outer glass envelope is damaged. Most modern CRTs used in televisions and computer displays include a bonded, multi-layer faceplate that prevents implosion if the faceplate is damaged, but the bell of the CRT (back portions of the glass envelope) offers no such protection. Certain specialized CRTs (such as those used in oscilloscopes) do not even offer a bonded faceplate; these CRTs require an external plastic faceplate or other cover to render them implosion safe while in use. Before the use of bonded faceplates one of the hazards would be that a broken neck or envelope would cause the neck and electron gun to be propelled by atmosperic pressure at such a velocity that it would erupt through the face of the tube.
When handling or disposing of a CRT, you must take steps to avoid creating an implosion hazard for you or your trash removal service. The most simple and safe method to make the tube safe is to identify the small sealed glass nib at the far back of the tube (this may be obscured by the electrical connector) and then (while wearing safety glasses and gloves) filing a small nick across this and then to break it off using a pair of pliers. A loud sucking sound will be heard as the air enters the tube, releasing the vacuum. One must be very cautious not to break the neck of the tube when it is evacuated since there is no plastic coating preventing shattering of the glass. High vacuum and high voltage can be dangerous.
See also
- Flat panel display
- Comparison of display technology
- Monoscope
- Image Dissector
- Charactron
Category:Displays
Category:Vacuum tubes
Category:Display technology
Category:Television technology
External links
- [http://members.chello.nl/~h.dijkstra19/page3.html The Cathode Ray Tube site]
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Category:Microprocessors
This is the category of microprocessors (µPs). For specialized µPs, and for the most extensive µP families, see the subcategories listed below.
Category:Computer hardware
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