1.
Raspberry Pi
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The original model became far more popular than anticipated, selling outside of its target market for uses such as robotics. Peripherals are not included with the Raspberry Pi, some accessories however have been included in several official and unofficial bundles. According to the Raspberry Pi Foundation, over 5 million Raspberry Pis have been sold before February 2015, by 9 September 2016 they had sold 10 million. Several generations of Raspberry Pis have been released, the first generation was released in February 2012. It was followed by a simpler and inexpensive model Model A, in 2014, the foundation released a board with an improved design in Raspberry Pi 1 Model B+. These boards are approximately credit-card sized and represent the standard mainline form-factor, improved A+ and B+ models were released a year later. The Raspberry Pi 2 which added more RAM was released in February 2015, Raspberry Pi 3 Model B released in February 2016 is bundled with on-board WiFi, Bluetooth and USB Boot capabilities. As of January 2017, Raspberry Pi 3 Model B is the newest mainline Raspberry Pi, Raspberry Pi boards are priced between US$5–35. As of 28 February 2017, the Raspberry PI Zero W was launched, which is identical to the Raspberry PI Zero, all models feature a Broadcom system on a chip, which includes an ARM compatible central processing unit and an on-chip graphics processing unit. CPU speed ranges from 700 MHz to 1.2 GHz for the Pi 3, secure Digital cards are used to store the operating system and program memory in either the SDHC or MicroSDHC sizes. Most boards have between one and four USB slots, HDMI and composite video output, and a 3.5 mm phone jack for audio, lower level output is provided by a number of GPIO pins which support common protocols like I²C. The B-models have an 8P8C Ethernet port and the Pi 3 and Pi Zero W have on board Wi-Fi 802. 11n and Bluetooth. The Foundation provides Raspbian, a Debian-based Linux distribution for download, as well as third party Ubuntu, Windows 10 IOT Core, RISC OS and it promotes Python and Scratch as the main programming language, with support for many other languages. The default firmware is closed source, while an open source is available. The Raspberry Pi hardware has evolved through several versions that feature variations in memory capacity and this block diagram depicts Models A, B, A+, and B+. Model A, A+, and the Pi Zero lack the Ethernet and USB hub components. The Ethernet adapter is connected to an additional USB port. In Model A, A+, and the PI Zero, the USB port is connected directly to the system on a chip. On the Pi 1 Model B+ and later models the USB/Ethernet chip contains a five-point USB hub, on the Pi Zero, the USB port is also connected directly to the SoC, but it uses a micro USB port
2.
Computer science
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Computer science is the study of the theory, experimentation, and engineering that form the basis for the design and use of computers. An alternate, more succinct definition of science is the study of automating algorithmic processes that scale. A computer scientist specializes in the theory of computation and the design of computational systems and its fields can be divided into a variety of theoretical and practical disciplines. Some fields, such as computational complexity theory, are highly abstract, other fields still focus on challenges in implementing computation. Human–computer interaction considers the challenges in making computers and computations useful, usable, the earliest foundations of what would become computer science predate the invention of the modern digital computer. Machines for calculating fixed numerical tasks such as the abacus have existed since antiquity, further, algorithms for performing computations have existed since antiquity, even before the development of sophisticated computing equipment. Wilhelm Schickard designed and constructed the first working mechanical calculator in 1623, in 1673, Gottfried Leibniz demonstrated a digital mechanical calculator, called the Stepped Reckoner. He may be considered the first computer scientist and information theorist, for, among other reasons and he started developing this machine in 1834, and in less than two years, he had sketched out many of the salient features of the modern computer. A crucial step was the adoption of a card system derived from the Jacquard loom making it infinitely programmable. Around 1885, Herman Hollerith invented the tabulator, which used punched cards to process statistical information, when the machine was finished, some hailed it as Babbages dream come true. During the 1940s, as new and more powerful computing machines were developed, as it became clear that computers could be used for more than just mathematical calculations, the field of computer science broadened to study computation in general. Computer science began to be established as an academic discipline in the 1950s. The worlds first computer science program, the Cambridge Diploma in Computer Science. The first computer science program in the United States was formed at Purdue University in 1962. Since practical computers became available, many applications of computing have become distinct areas of study in their own rights and it is the now well-known IBM brand that formed part of the computer science revolution during this time. IBM released the IBM704 and later the IBM709 computers, still, working with the IBM was frustrating if you had misplaced as much as one letter in one instruction, the program would crash, and you would have to start the whole process over again. During the late 1950s, the science discipline was very much in its developmental stages. Time has seen significant improvements in the usability and effectiveness of computing technology, modern society has seen a significant shift in the users of computer technology, from usage only by experts and professionals, to a near-ubiquitous user base
3.
Computer
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A computer is a device that can be instructed to carry out an arbitrary set of arithmetic or logical operations automatically. The ability of computers to follow a sequence of operations, called a program, such computers are used as control systems for a very wide variety of industrial and consumer devices. The Internet is run on computers and it millions of other computers. Since ancient times, simple manual devices like the abacus aided people in doing calculations, early in the Industrial Revolution, some mechanical devices were built to automate long tedious tasks, such as guiding patterns for looms. More sophisticated electrical machines did specialized analog calculations in the early 20th century, the first digital electronic calculating machines were developed during World War II. The speed, power, and versatility of computers has increased continuously and dramatically since then, conventionally, a modern computer consists of at least one processing element, typically a central processing unit, and some form of memory. The processing element carries out arithmetic and logical operations, and a sequencing, peripheral devices include input devices, output devices, and input/output devices that perform both functions. Peripheral devices allow information to be retrieved from an external source and this usage of the term referred to a person who carried out calculations or computations. The word continued with the same meaning until the middle of the 20th century, from the end of the 19th century the word began to take on its more familiar meaning, a machine that carries out computations. The Online Etymology Dictionary gives the first attested use of computer in the 1640s, one who calculates, the Online Etymology Dictionary states that the use of the term to mean calculating machine is from 1897. The Online Etymology Dictionary indicates that the use of the term. 1945 under this name, theoretical from 1937, as Turing machine, devices have been used to aid computation for thousands of years, mostly using one-to-one correspondence with fingers. The earliest counting device was probably a form of tally stick, later record keeping aids throughout the Fertile Crescent included calculi which represented counts of items, probably livestock or grains, sealed in hollow unbaked clay containers. The use of counting rods is one example, the abacus was initially used for arithmetic tasks. The Roman abacus was developed from used in Babylonia as early as 2400 BC. Since then, many forms of reckoning boards or tables have been invented. In a medieval European counting house, a checkered cloth would be placed on a table, the Antikythera mechanism is believed to be the earliest mechanical analog computer, according to Derek J. de Solla Price. It was designed to calculate astronomical positions and it was discovered in 1901 in the Antikythera wreck off the Greek island of Antikythera, between Kythera and Crete, and has been dated to circa 100 BC
4.
Printed circuit board
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Components are generally soldered on the PCB. Advanced PCBs may contain components embedded in the substrate, PCBs can be single sided, double sided or multi-layer. Conductors on different layers are connected with vias, multi-layer PCBs allow for much higher component density. FR-4 glass epoxy is the primary insulating substrate, a basic building block of the PCB is an FR-4 panel with a thin layer of copper foil laminated to one or both sides. In multi-layer boards multiple layers of material are laminated together, printed circuit boards are used in all but the simplest electronic products. Alternatives to PCBs include wire wrap and point-to-point construction, PCBs require the additional design effort to lay out the circuit, but manufacturing and assembly can be automated. Manufacturing circuits with PCBs is cheaper and faster than other wiring methods as components are mounted and wired with one single part. A minimal PCB with a component used for easier prototyping is called a breakout board. When the board has no embedded components it is correctly called a printed wiring board or etched wiring board. However, the printed wiring board has fallen into disuse. A PCB populated with electronic components is called a printed circuit assembly, the IPC preferred term for assembled boards is circuit card assembly, and for assembled backplanes it is backplane assemblies. The term PCB is used both for bare and assembled boards. The world market for bare PCBs exceeded $60.2 billion in 2014, initially PCBs were designed manually by creating a photomask on a clear mylar sheet, usually at two or four times the true size. Starting from the diagram the component pin pads were laid out on the mylar. Rub-on dry transfers of common component footprints increased efficiency, traces were made with self-adhesive tape. Pre-printed non-reproducing grids on the mylar assisted in layout, to fabricate the board, the finished photomask was photolithographically reproduced onto a photoresist coating on the blank copper-clad boards. Modern PCBs are designed with dedicated software, generally in the following steps. Card dimensions and template are decided based on required circuitry and case of the PCB, the positions of the components and heat sinks are determined
5.
Microprocessor
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A microprocessor is a computer processor which incorporates the functions of a computers central processing unit on a single integrated circuit, or at most a few integrated circuits. Microprocessors contain both combinational logic and sequential digital logic, Microprocessors operate on numbers and symbols represented in the binary numeral system. The integration of a whole CPU onto a chip or on a few chips greatly reduced the cost of processing power. Integrated circuit processors are produced in numbers by highly automated processes resulting in a low per unit cost. Single-chip processors increase reliability as there are many electrical connections to fail. As microprocessor designs get better, the cost of manufacturing a chip generally stays the same, before microprocessors, small computers had been built using racks of circuit boards with many medium- and small-scale integrated circuits. Microprocessors combined this into one or a few large-scale ICs, the internal arrangement of a microprocessor varies depending on the age of the design and the intended purposes of the microprocessor. Advancing technology makes more complex and powerful chips feasible to manufacture, a minimal hypothetical microprocessor might only include an arithmetic logic unit and a control logic section. The ALU performs operations such as addition, subtraction, and operations such as AND or OR, each operation of the ALU sets one or more flags in a status register, which indicate the results of the last operation. The control logic retrieves instruction codes from memory and initiates the sequence of operations required for the ALU to carry out the instruction, a single operation code might affect many individual data paths, registers, and other elements of the processor. As integrated circuit technology advanced, it was feasible to manufacture more and more complex processors on a single chip, the size of data objects became larger, allowing more transistors on a chip allowed word sizes to increase from 4- and 8-bit words up to todays 64-bit words. Additional features were added to the architecture, more on-chip registers sped up programs. Floating-point arithmetic, for example, was not available on 8-bit microprocessors. Integration of the point unit first as a separate integrated circuit and then as part of the same microprocessor chip. Occasionally, physical limitations of integrated circuits made such practices as a bit slice approach necessary, instead of processing all of a long word on one integrated circuit, multiple circuits in parallel processed subsets of each data word. With the ability to put large numbers of transistors on one chip and this CPU cache has the advantage of faster access than off-chip memory, and increases the processing speed of the system for many applications. Processor clock frequency has increased more rapidly than external memory speed, except in the recent past, a microprocessor is a general purpose system. Several specialized processing devices have followed from the technology, A digital signal processor is specialized for signal processing, graphics processing units are processors designed primarily for realtime rendering of 3D images
6.
Random-access memory
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Random-access memory is a form of computer data storage which stores frequently used program instructions to increase the general speed of a system. A random-access memory device allows data items to be read or written in almost the same amount of time irrespective of the location of data inside the memory. RAM contains multiplexing and demultiplexing circuitry, to connect the lines to the addressed storage for reading or writing the entry. Usually more than one bit of storage is accessed by the same address, in todays technology, random-access memory takes the form of integrated circuits. RAM is normally associated with types of memory, where stored information is lost if power is removed. Other types of non-volatile memories exist that allow access for read operations. These include most types of ROM and a type of memory called NOR-Flash. Integrated-circuit RAM chips came into the market in the early 1970s, with the first commercially available DRAM chip, early computers used relays, mechanical counters or delay lines for main memory functions. Ultrasonic delay lines could only reproduce data in the order it was written, drum memory could be expanded at relatively low cost but efficient retrieval of memory items required knowledge of the physical layout of the drum to optimize speed. Latches built out of vacuum tube triodes, and later, out of transistors, were used for smaller and faster memories such as registers. Such registers were relatively large and too costly to use for large amounts of data, the first practical form of random-access memory was the Williams tube starting in 1947. It stored data as electrically charged spots on the face of a cathode ray tube, since the electron beam of the CRT could read and write the spots on the tube in any order, memory was random access. The capacity of the Williams tube was a few hundred to around a thousand bits, but it was smaller, faster. In fact, rather than the Williams tube memory being designed for the SSEM, magnetic-core memory was invented in 1947 and developed up until the mid-1970s. It became a form of random-access memory, relying on an array of magnetized rings. By changing the sense of each rings magnetization, data could be stored with one bit stored per ring, since every ring had a combination of address wires to select and read or write it, access to any memory location in any sequence was possible. Magnetic core memory was the form of memory system until displaced by solid-state memory in integrated circuits. Data was stored in the capacitance of each transistor, and had to be periodically refreshed every few milliseconds before the charge could leak away
7.
Embedded system
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An embedded system is a computer system with a dedicated function within a larger mechanical or electrical system, often with real-time computing constraints. It is embedded as part of a device often including hardware. Embedded systems control many devices in use today. Ninety-eight percent of all microprocessors are manufactured as components of embedded systems, examples of properties of typically embedded computers when compared with general-purpose counterparts are low power consumption, small size, rugged operating ranges, and low per-unit cost. This comes at the price of limited processing resources, which make them more difficult to program. For example, intelligent techniques can be designed to power consumption of embedded systems. Modern embedded systems are based on microcontrollers, but ordinary microprocessors are also common. In either case, the processor used may be ranging from general purpose to those specialised in certain class of computations. A common standard class of dedicated processors is the signal processor. Since the embedded system is dedicated to tasks, design engineers can optimize it to reduce the size and cost of the product and increase the reliability. Some embedded systems are mass-produced, benefiting from economies of scale, complexity varies from low, with a single microcontroller chip, to very high with multiple units, peripherals and networks mounted inside a large chassis or enclosure. One of the very first recognizably modern embedded systems was the Apollo Guidance Computer, an early mass-produced embedded system was the Autonetics D-17 guidance computer for the Minuteman missile, released in 1961. When the Minuteman II went into production in 1966, the D-17 was replaced with a new computer that was the first high-volume use of integrated circuits. Since these early applications in the 1960s, embedded systems have come down in price and there has been a rise in processing power. An early microprocessor for example, the Intel 4004, was designed for calculators and other systems but still required external memory. By the early 1980s, memory, input and output system components had been integrated into the chip as the processor forming a microcontroller. Microcontrollers find applications where a computer would be too costly. A comparatively low-cost microcontroller may be programmed to fulfill the role as a large number of separate components
8.
Home computer
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Home computers were a class of microcomputers entering the market in 1977, and becoming common during the 1980s. They were marketed to consumers as affordable and accessible computers that, however, a home computer often had better graphics and sound than contemporaneous business computers. Their most common uses were playing games, but they were also regularly used for word processing, doing homework. Home computers were usually not electronic kits, home computers were already manufactured in stylish metal or plastic enclosures. There were, however, commercial kits like the Sinclair ZX80 which were home and home-built computers since the purchaser could assemble the unit from a kit. For example, using a typical 1980s home computer as a home automation appliance would require the computer to be powered on at all times. Personal finance and database use required tedious data entry, by contrast, advertisements in the specialty computer press often simply listed specifications. Since most systems shipped with the BASIC programming language included on the system ROM, many users found programming to be a fun and rewarding experience, and an excellent introduction to the world of digital technology. Often the only difference may be the outlet through which they are purchased. Another change from the computer era is that the once-common endeavour of writing ones own software programs has almost vanished from home computer use. As early as 1965, some projects such as Jim Sutherlands ECHO IV explored the possible utility of a computer in the home. In 1969, the Honeywell Kitchen Computer was marketed as a gift item, and would have inaugurated the era of home computing. Computers became affordable for the public in the 1970s due to the mass production of the microprocessor starting in 1971. Early microcomputers such as the Altair 8800 had front-mounted switches and diagnostic lights to control and indicate internal system status, while two early home computers could be bought either in kit form or assembled, most home computers were only sold pre-assembled. The keyboard - a feature lacking on the Altair - was usually built into the case as the motherboard. Ports for plug-in peripheral devices such as a display, cassette tape recorders, joysticks. Usually the manufacturer would sell peripheral devices designed to be compatible with their computers as extra cost accessories, peripherals were not often interchangeable between different brands of home computer, or even between successive models of the same brand. To save the cost of a monitor, the home computer would often connect through an RF modulator to the family TV set
9.
Portable computer
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A portable computer is a computer that is designed to be moved from one place to another and includes a display and keyboard. Portable computers, by their nature, are generally microcomputers, Portable computers, because of their size, are also commonly known as Lunchbox or Luggable computers. They can also be called a Portable Workstation or Portable PC, in Japan they are often called Bentocom. The principal advantage of a portable computer versus a laptop or other computing device is the use of standard motherboards or backplanes providing plug-in slots for add-in cards. This allows mission specific cards such as test, A/D, or communication protocol to be installed, Portable computers also provide for more disk storage by using standard 3-1/2 drives and providing for multiple drives. SCAMP emulated an IBM1130 minicomputer in order to run APL\1130, in 1973 APL was generally available only on mainframe computers, and most desktop sized microcomputers such as the Wang 2200 or HP9800 offered only BASIC. Because SCAMP was the first to emulate APL\1130 performance on a portable, single computer, PC Magazine in 1983 designated SCAMP a revolutionary concept. Successful demonstrations of the 1973 SCAMP prototype led to the first commercial IBM5100 portable microcomputer launched in 1975, in the late 1960s such a machine would have been nearly as large as two desks and would have weighed about half a ton. The MIT Suitcase Computer, constructed in 1975, was the first known microprocessor-based portable computer and it was based on the Motorola 6800. Built by student David Emberson in the MIT Digital Systems Laboratory as a thesis project and it is currently in the collection of Dr. Hoo-Min D. Toong. An early portable computer was manufactured in 1979 by GM Research, the machine which was designed and patented by James Murez. It was called the Micro Star and later changed the name to The Small One, as early as 1979 the U. S. Government was contracting to purchase these machines. Other major customers included Sandia Labs, General Dynamics, BBN and several private individuals. In 1979, Adam Osborne viewed the machine along with several hundred visitors at the first computer show that was sponsored by the IEEE Westec in Los Angeles. Later that year the machine was shown at the first COMDEX show. The first mass-produced microprocessor-based portable computer released in 1981 was the Osborne 1, developed by Osborne, another early portable computer released in 1982 was the Kaypro. In January 1983, the first IBM PC compatible portable computer was the Compaq Portable, the first full-color portable computer was the Commodore SX-64 in January 1984. Apple Inc. introduced and released Macintosh Portable in 1989, smaller portable computers are also known as mobile computers
10.
Personal computer
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A personal computer is a multi-purpose electronic computer whose size, capabilities, and price make it feasible for individual use. PCs are intended to be operated directly by a end-user, rather than by an expert or technician. In the 2010s, PCs are typically connected to the Internet, allowing access to the World Wide Web, personal computers may be connected to a local area network, either by a cable or a wireless connection. In the 2010s, a PC may be, a multi-component desktop computer, designed for use in a location a laptop computer, designed for easy portability or a tablet computer. In the 2010s, PCs run using a system, such as Microsoft Windows, Linux. The very earliest microcomputers, equipped with a front panel, required hand-loading of a program to load programs from external storage. Before long, automatic booting from permanent read-only memory became universal, in the 2010s, users have access to a wide range of commercial software, free software and free and open-source software, which are provided in ready-to-run or ready-to-compile form. Since the early 1990s, Microsoft operating systems and Intel hardware have dominated much of the computer market, first with MS-DOS. Alternatives to Microsofts Windows operating systems occupy a minority share of the industry and these include Apples OS X and free open-source Unix-like operating systems such as Linux and Berkeley Software Distribution. Advanced Micro Devices provides the alternative to Intels processors. PC is an initialism for personal computer, some PCs, including the OLPC XOs, are equipped with x86 or x64 processors but not designed to run Microsoft Windows. PC is used in contrast with Mac, an Apple Macintosh computer and this sense of the word is used in the Get a Mac advertisement campaign that ran between 2006 and 2009, as well as its rival, Im a PC campaign, that appeared in 2008. Since Apples transition to Intel processors starting 2005, all Macintosh computers are now PCs, the “brain” may one day come down to our level and help with our income-tax and book-keeping calculations. But this is speculation and there is no sign of it so far, in the history of computing there were many examples of computers designed to be used by one person, as opposed to terminals connected to mainframe computers. Using the narrow definition of operated by one person, the first personal computer was the ENIAC which became operational in 1946 and it did not meet further definitions of affordable or easy to use. An example of an early single-user computer was the LGP-30, created in 1956 by Stan Frankel and used for science and it came with a retail price of $47, 000—equivalent to about $414,000 today. Introduced at the 1965 New York Worlds Fair, the Programma 101 was a programmable calculator described in advertisements as a desktop computer. It was manufactured by the Italian company Olivetti and invented by the Italian engineer Pier Giorgio Perotto, the Soviet MIR series of computers was developed from 1965 to 1969 in a group headed by Victor Glushkov
11.
Expansion card
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An expansion bus is a computer bus which moves information between the internal hardware of a computer system and peripheral devices. It is a collection of wires and protocols that allows for the expansion of a computer, even vacuum-tube based computers had modular construction, but individual functions for peripheral devices filled a cabinet, not just a printed circuit board. Processor, memory and I/O cards became feasible with the development of integrated circuits, minicomputers, starting with the PDP-8, were made of multiple cards, all powered by and communicating through a passive backplane. The first commercial microcomputer to feature expansion slots was the Micral N, proprietary bus implementations for systems such as the Apple II co-existed with multi-manufacturer standards. IBM introduced what would retroactively be called the Industry Standard Architecture bus with the IBM PC in 1981, the IBM XT, introduced in 1983, used the same bus. The 8-bit PC and XT bus was extended with the introduction of the IBM AT and this used a second connector for extending the address and data bus over the XT, but was backward compatible, 8-bit cards were still usable in the AT 16-bit slots. Industry Standard Architecture became the designation for the IBM AT bus after other types were developed. IBMs MCA bus, developed for the PS/2 in 1987, was a competitor to ISA, also their design, but fell out of favor due to the ISAs industry-wide acceptance and IBMs licensing of MCA. EISA, the 32-bit extended version of ISA championed by Compaq, was used on some PC motherboards until 1997, proprietary local buses and then the VESA Local Bus Standard, were late 1980s expansion buses that were tied but not exclusive to the 80386 and 80486 CPU bus. The PC/104 bus is a bus that copies the ISA bus. Intel launched their PCI bus chipsets along with the P5-based Pentium CPUs in 1993, the PCI bus was introduced in 1991 as replacement for ISA. The standard is found on PC motherboards to this day, the PCI standard supports bus bridging, as many as ten daisy chained PCI buses have been tested. Cardbus, using the PCMCIA connector, is a PCI format that attaches peripherals to the Host PCI Bus via PCI to PCI Bridge, cardbus is being supplanted by ExpressCard format. Intel introduced the AGP bus in 1997 as a video acceleration solution. AGP devices are attached to the PCI bus over a PCI-to-PCI bridge. Though termed a bus, AGP usually supports only a card at a time. From 2005 PCI-Express has been replacing both PCI and AGP and this standard, approved in 2004, implements the logical PCI protocol over a serial communication interface. PC/104 or Mini PCI are often added for expansion on small form factor boards such as Mini-ITX, for their 1000 EX and 1000 HX models, Tandy Computer designed the PLUS expansion interface, an adaptation of the XT-bus supporting cards of a smaller form factor
12.
Blade server
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A blade server is a stripped-down server computer with a modular design optimized to minimize the use of physical space and energy. Blade servers have many components removed to save space, minimize power consumption and other considerations, unlike a rack-mount server, a blade server needs a blade enclosure, which can hold multiple blade servers, providing services such as power, cooling, networking, various interconnects and management. Together, blades and the enclosure, form a blade system. Different blade providers have differing principles regarding what to include in the blade itself, in a standard server-rack configuration, one rack unit or 1U—19 inches wide and 1.75 inches tall—defines the minimum possible size of any equipment. The principal benefit and justification of blade computing relates to lifting this restriction so as to size requirements. The most common computer rack form-factor is 42U high, which limits the number of computer devices directly mountable in a rack to 42 components. Blades do not have this limitation, as of 2014, densities of up to 180 servers per blade system are achievable with blade systems. Enclosure performs many of the non-core computing services found in most computers, non-blade systems typically use bulky, hot and space-inefficient components, and may duplicate these across many computers that may or may not perform at capacity. By locating these services in one place and sharing them among the blade computers, the specifics of which services are provided varies by vendor. Computers operate over a range of DC voltages, but utilities deliver power as AC, converting this current requires one or more power supply units. The blade enclosures power supply provides a power source for all blades within the enclosure. This single power source may come as a supply in the enclosure or as a dedicated separate PSU supplying DC to multiple enclosures. This setup reduces the number of PSUs required to provide a resilient power supply, during operation, electrical and mechanical components produce heat, which a system must dissipate to ensure the proper functioning of its components. Most blade enclosures, like most computing systems, remove heat by using fans, the blades shared power and cooling means that it does not generate as much heat as traditional servers. Newer blade-enclosures feature variable-speed fans and control logic, or even liquid cooling systems that adjust to meet the cooling requirements. At the same time, the density of blade-server configurations can still result in higher overall demands for cooling with racks populated at over 50% full. This is especially true with early-generation blades, in absolute terms, a fully populated rack of blade servers is likely to require more cooling capacity than a fully populated rack of standard 1U servers. This is because one can fit up to 128 blade servers in the rack that will only hold 42 1U rack mount servers
