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92-532: The company started as a manufacturer of complete motherboards , positioning itself in the high-end segment. Its first customer was PCs Limited, later known as Dell Computer . As hardware activity moved progressively to Taiwan -based original design manufacturers , AMI continued to develop BIOS firmware for major motherboard manufacturers. The company produced BIOS software for motherboards (1986), server motherboards (1992), storage controllers (1995) and remote-management cards (1998). In 1993, AMI produced MegaRAID,

184-444: A BIOS , as did the boot ROM on the original IBM PC, or UEFI . UEFI is a successor to BIOS that became popular after Microsoft began requiring it for a system to be certified to run Windows 8 . When the computer is powered on, the boot firmware tests and configures memory, circuitry, and peripherals. This Power-On Self Test (POST) may include testing some of the following things: Substitution cipher In cryptography ,

276-516: A Feistel cipher ), so it is possible – from this extreme perspective – to consider modern block ciphers as a type of polygraphic substitution. Between around World War I and the widespread availability of computers (for some governments this was approximately the 1950s or 1960s; for other organizations it was a decade or more later; for individuals it was no earlier than 1975), mechanical implementations of polyalphabetic substitution ciphers were widely used. Several inventors had similar ideas about

368-475: A substitution cipher is a method of encrypting in which units of plaintext are replaced with the ciphertext , in a defined manner, with the help of a key; the "units" may be single letters (the most common), pairs of letters, triplets of letters, mixtures of the above, and so forth. The receiver deciphers the text by performing the inverse substitution process to extract the original message. Substitution ciphers can be compared with transposition ciphers . In

460-510: A tabula recta had been employed. As such, even today a Vigenère type cipher should theoretically be difficult to break if mixed alphabets are used in the tableau, if the keyword is random, and if the total length of ciphertext is less than 27.67 times the length of the keyword. These requirements are rarely understood in practice, and so Vigenère enciphered message security is usually less than might have been. Other notable polyalphabetics include: Modern stream ciphers can also be seen, from

552-615: A water cooling system instead of many fans. Some small form factor computers and home theater PCs designed for quiet and energy-efficient operation boast fan-less designs. This typically requires the use of a low-power CPU, as well as a careful layout of the motherboard and other components to allow for heat sink placement. A 2003 study found that some spurious computer crashes and general reliability issues, ranging from screen image distortions to I/O read/write errors, can be attributed not to software or peripheral hardware but to aging capacitors on PC motherboards. Ultimately this

644-401: A PCB with expansion capabilities. As the name suggests, this board is often referred to as the mother of all components attached to it, which often include peripherals, interface cards, and daughterboards : sound cards , video cards , network cards , host bus adapters , TV tuner cards , IEEE 1394 cards, and a variety of other custom components. Similarly, the term mainboard describes

736-458: A company called Quintessential Consultants Inc. (QCI), and later set up an equal partnership with Shankar. By this time the AMIBIOS had become established and there was a need to keep the initials AMI. The partners renamed QCI as American Megatrends Inc., with the same initials as Access Methods Inc.; the renamed company then purchased AMIBIOS from Access Methods. Shankar became the president and Sarma

828-468: A device with a single board and no additional expansions or capability, such as controlling boards in laser printers, television sets, washing machines, mobile phones, and other embedded systems with limited expansion abilities. Prior to the invention of the microprocessor , the CPU of a digital computer consisted of multiple circuit boards in a card-cage case with components connected by a backplane containing

920-406: A different number of connections depending on its standard and form factor . A standard, modern ATX motherboard will typically have two or three PCI-Express x16 connection for a graphics card, one or two legacy PCI slots for various expansion cards, and one or two PCI-E x1 (which has superseded PCI ). A standard EATX motherboard will have two to four PCI-E x16 connection for graphics cards, and

1012-460: A grid. For example: Such features make little difference to the security of a scheme, however – at the very least, any set of strange symbols can be transcribed back into an A-Z alphabet and dealt with as normal. In lists and catalogues for salespeople, a very simple encryption is sometimes used to replace numeric digits by letters. Examples: MAT would be used to represent 120, PAPR would be used for 5256, and OFTK would be used for 7803. Although

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1104-423: A lifetime of 3 to 4 years can be expected. However, many manufacturers deliver substandard capacitors, which significantly reduce life expectancy. Inadequate case cooling and elevated temperatures around the CPU socket exacerbate this problem. With top blowers, the motherboard components can be kept under 95 °C (203 °F), effectively doubling the motherboard lifetime. Mid-range and high-end motherboards, on

1196-619: A mixed alphabet (two letters, usually I and J, are combined). A digraphic substitution is then simulated by taking pairs of letters as two corners of a rectangle, and using the other two corners as the ciphertext (see the Playfair cipher main article for a diagram). Special rules handle double letters and pairs falling in the same row or column. Playfair was in military use from the Boer War through World War II . Several other practical polygraphics were introduced in 1901 by Felix Delastelle , including

1288-550: A peripheral device. If no peripheral device containing an operating system was available, then the computer would perform tasks from other ROM stores or display an error message, depending on the model and design of the computer. For example, both the Apple II and the original IBM PC had Cassette BASIC (ROM BASIC) and would start that if no operating system could be loaded from the floppy disk or hard disk. The boot firmware in modern IBM PC compatible motherboard designs contains either

1380-448: A separate component. Business PCs, workstations, and servers were more likely to need expansion cards, either for more robust functions, or for higher speeds; those systems often had fewer embedded components. Laptop and notebook computers that were developed in the 1990s integrated the most common peripherals. This even included motherboards with no upgradeable components, a trend that would continue as smaller systems were introduced after

1472-424: A set of interconnected sockets into which the circuit boards are plugged. In very old designs, copper wires were the discrete connections between card connector pins, but printed circuit boards soon became the standard practice. The central processing unit (CPU), memory, and peripherals were housed on individually printed circuit boards, which were plugged into the backplane. In older microprocessor-based systems,

1564-412: A set of low-speed peripherals: PS/2 keyboard and mouse , floppy disk drive , serial ports , and parallel ports . By the late 1990s, many personal computer motherboards included consumer-grade embedded audio, video, storage, and networking functions without the need for any expansion cards at all; higher-end systems for 3D gaming and computer graphics typically retained only the graphics card as

1656-765: A storage controller card . AMI sold its RAID assets to LSI Corporation in 2001, with only one employee from the RAID-division remaining with the AMI core team. AMI continued to focus on OEM and ODM business and technology. Its product line includes or has previously included AMIBIOS (a BIOS ), Aptio (a successor to AMIBIOS8 based on the UEFI standard), diagnostic software, AMI EC ( embedded controller firmware), MG-Series SGPIO backplane controllers (for SATA , SAS and NVMe storage devices), driver/firmware development, and MegaRAC ( BMC firmware). American Megatrends Inc. (AMI)

1748-478: A sufficiently abstract perspective, to be a form of polyalphabetic cipher in which all the effort has gone into making the keystream as long and unpredictable as possible. In a polygraphic substitution cipher, plaintext letters are substituted in larger groups, instead of substituting letters individually. The first advantage is that the frequency distribution is much flatter than that of individual letters (though not actually flat in real languages; for example, 'OS'

1840-465: A system, with a 20 x 20 tableau (for the 20 letters of the Italian/Latin alphabet he was using) filled with 400 unique glyphs . However the system was impractical and probably never actually used. The earliest practical digraphic cipher (pairwise substitution), was the so-called Playfair cipher , invented by Sir Charles Wheatstone in 1854. In this cipher, a 5 x 5 grid is filled with the letters of

1932-424: A transposition cipher, the units of the plaintext are rearranged in a different and usually quite complex order, but the units themselves are left unchanged. By contrast, in a substitution cipher, the units of the plaintext are retained in the same sequence in the ciphertext, but the units themselves are altered. There are a number of different types of substitution cipher. If the cipher operates on single letters, it

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2024-689: A variety of sizes and shapes called form factors , some of which are specific to individual computer manufacturers. However, the motherboards used in IBM-compatible systems are designed to fit various case sizes. As of 2024 , most desktop computer motherboards use the ATX standard form factor — even those found in Macintosh and Sun computers, which have not been built from commodity components. A case's motherboard and power supply unit (PSU) form factor must all match, though some smaller form factor motherboards of

2116-515: A varying number of PCI and PCI-E x1 slots. It can sometimes also have a PCI-E x4 slot (will vary between brands and models). Some motherboards have two or more PCI-E x16 slots, to allow more than 2 monitors without special hardware, or use a special graphics technology called SLI (for Nvidia ) and Crossfire (for AMD ). These allow 2 to 4 graphics cards to be linked together, to allow better performance in intensive graphical computing tasks, such as gaming, video editing, etc. In newer motherboards,

2208-477: Is a product line of baseboard management controller firmware packages and formerly Service Processors providing Out-of-band , or Lights-out remote management of computer systems. These baseboard management controllers running MegaRAC firmware packages or service processors operate independently of the Operating System status or location, to manage and troubleshoot computers. AMIBIOS (also written as AMI BIOS)

2300-482: Is a story of buried treasure that was described in 1819–21 by use of a ciphered text that was keyed to the Declaration of Independence. Here each ciphertext character was represented by a number. The number was determined by taking the plaintext character and finding a word in the Declaration of Independence that started with that character and using the numerical position of that word in the Declaration of Independence as

2392-414: Is called a tabula recta , and mathematically corresponds to adding the plaintext and key letters, modulo 26.) A keyword is then used to choose which ciphertext alphabet to use. Each letter of the keyword is used in turn, and then they are repeated again from the beginning. So if the keyword is 'CAT', the first letter of plaintext is enciphered under alphabet 'C', the second under 'A', the third under 'T',

2484-463: Is handled without affecting data. It supports High-availability cluster , redundancy, scalability, replication, disaster recovery and multiple site backups. DuOS-M was commercial software developed by American Megatrends for Intel x86 -based computers using the Microsoft Windows operating system to provide a "dual operating system" environment in which the user can simultaneously deploy

2576-463: Is much more common than 'RÑ' in Spanish). Second, the larger number of symbols requires correspondingly more ciphertext to productively analyze letter frequencies. To substitute pairs of letters would take a substitution alphabet 676 symbols long ( 26 2 {\displaystyle 26^{2}} ). In the same De Furtivis Literarum Notis mentioned above, della Porta actually proposed such

2668-477: Is not very strong, and is easily broken. Provided the message is of reasonable length (see below), the cryptanalyst can deduce the probable meaning of the most common symbols by analyzing the frequency distribution of the ciphertext. This allows formation of partial words, which can be tentatively filled in, progressively expanding the (partial) solution (see frequency analysis for a demonstration of this). In some cases, underlying words can also be determined from

2760-487: Is termed a simple substitution cipher ; a cipher that operates on larger groups of letters is termed polygraphic . A monoalphabetic cipher uses fixed substitution over the entire message, whereas a polyalphabetic cipher uses a number of substitutions at different positions in the message, where a unit from the plaintext is mapped to one of several possibilities in the ciphertext and vice versa. The first ever published description of how to crack simple substitution ciphers

2852-647: Is the IBM PC -compatible BIOS that was formerly developed and sold by American Megatrends since 1986. In 1994, the company claimed that 75% of PC clones used AMIBIOS. It is used on motherboards made by AMI and by other companies. American Megatrends had a strict OEM business model for AMIBIOS: it sold source code to motherboard manufacturers or customized AMIBIOS for each OEM individually, whichever business model they require. AMI does not sell to end users, and itself produces no end-user documentation or technical support for its BIOS firmware, leaving that to licensees. However,

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2944-406: Is usually more expensive than a desktop motherboard. A CPU socket (central processing unit) or slot is an electrical component that attaches to a printed circuit board (PCB) and is designed to house a CPU (also called a microprocessor). It is a special type of integrated circuit socket designed for very high pin counts. A CPU socket provides many functions, including a physical structure to support

3036-785: The Android operating system in tandem with Microsoft Windows. Because DuOS-M has the capability to run both Windows and Android simultaneously, the user can switch between the two operating systems without having to dual boot or suspend operation of one operating system in order to utilize the other. DuOS-M supports key hardware peripherals in Windows including cameras, audio, microphone and sensors such as ambient light sensor, accelerometer , gyrometer, compass and orientation sensors. It also supports various screen sizes, resolutions, and screen orientation (portrait and landscape) along with 3D acceleration and HD video playback. The first version of DuOS-M

3128-694: The Apple II and IBM PC include only this minimal peripheral support on the motherboard. Occasionally video interface hardware was also integrated into the motherboard; for example, on the Apple II and rarely on IBM-compatible computers such as the IBM PCjr . Additional peripherals such as disk controllers and serial ports were provided as expansion cards. Given the high thermal design power of high-speed computer CPUs and components, modern motherboards nearly always include heat sinks and mounting points for fans to dissipate excess heat. Motherboards are produced in

3220-472: The Apple II and IBM PC used ROM chips mounted in sockets on the motherboard. At power-up, the central processor unit would load its program counter with the address of the Boot ROM and start executing instructions from the Boot ROM. These instructions initialized and tested the system hardware, displayed system information on the screen, performed RAM checks, and then attempts to boot an operating system from

3312-505: The Caesar and Atbash ciphers, respectively) or scrambled in a more complex fashion, in which case it is called a mixed alphabet or deranged alphabet . Traditionally, mixed alphabets may be created by first writing out a keyword, removing repeated letters in it, then writing all the remaining letters in the alphabet in the usual order. Using this system, the keyword " zebras " gives us the following alphabets: A message enciphers to And

3404-429: The M.2 slots are for SSD and/or wireless network interface controller . Motherboards are generally air cooled with heat sinks often mounted on larger chips in modern motherboards. Insufficient or improper cooling can cause damage to the internal components of the computer, or cause it to crash . Passive cooling , or a single fan mounted on the power supply , was sufficient for many desktop computer CPU's until

3496-493: The SIGABA and Typex machines were ever broken during or near the time when these systems were in service. One type of substitution cipher, the one-time pad , is unique. It was invented near the end of World War I by Gilbert Vernam and Joseph Mauborgne in the US. It was mathematically proven unbreakable by Claude Shannon , probably during World War II ; his work was first published in

3588-403: The basis prime .) A block of n letters is then considered as a vector of n dimensions , and multiplied by a n x n matrix , modulo 26. The components of the matrix are the key, and should be random provided that the matrix is invertible in Z 26 n {\displaystyle \mathbb {Z} _{26}^{n}} (to ensure decryption is possible). A mechanical version of

3680-420: The bifid and four-square ciphers (both digraphic) and the trifid cipher (probably the first practical trigraphic). The Hill cipher , invented in 1929 by Lester S. Hill , is a polygraphic substitution which can combine much larger groups of letters simultaneously using linear algebra . Each letter is treated as a digit in base 26 : A = 0, B =1, and so on. (In a variation, 3 extra symbols are added to make

3772-671: The ACPI _OSI method, which is used by ACPI to determine the OS version (in case an ACPI patch only applies to one specific OS). In some cases, the OSI method caused problems on Linux systems, skipping code that was only executed on Windows systems. Foxconn and AMI worked together to develop a solution, which was included in later revisions of AMIBIOS. The issue affected motherboards with Intel Socket 775. Actual system behavior differed based on BIOS version, system hardware and Linux distribution . In October 2021 an issue

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3864-518: The CPU and some support circuitry would fit on a single CPU board, with memory and peripherals on additional boards, all plugged into the backplane. The ubiquitous S-100 bus of the 1970s is an example of this type of backplane system. The most popular computers of the 1980s such as the Apple II and IBM PC had published schematic diagrams and other documentation which permitted rapid reverse engineering and third-party replacement motherboards. Usually intended for building new computers compatible with

3956-420: The CPU series and speed. With the steadily declining costs and size of integrated circuits , it is now possible to include support for many peripherals on the motherboard. By combining many functions on one PCB , the physical size and total cost of the system may be reduced; highly integrated motherboards are thus especially popular in small form factor and budget computers. A typical motherboard will have

4048-515: The CPU, support for a heat sink, facilitating replacement (as well as reducing cost), and most importantly, forming an electrical interface both with the CPU and the PCB. CPU sockets on the motherboard can most often be found in most desktop and server computers (laptops typically use surface mount CPUs), particularly those based on the Intel x86 architecture. A CPU socket type and motherboard chipset must support

4140-631: The Enigma machine (those without the "plugboard") well before WWII began. Traffic protected by essentially all of the German military Enigmas was broken by Allied cryptanalysts, most notably those at Bletchley Park , beginning with the German Army variant used in the early 1930s. This version was broken by inspired mathematical insight by Marian Rejewski in Poland . As far as is publicly known, no messages protected by

4232-456: The Hill cipher of dimension 6 was patented in 1929. The Hill cipher is vulnerable to a known-plaintext attack because it is completely linear , so it must be combined with some non-linear step to defeat this attack. The combination of wider and wider weak, linear diffusive steps like a Hill cipher, with non-linear substitution steps, ultimately leads to a substitution–permutation network (e.g.

4324-467: The StorTrends iTX storage management firmware platform. StorTrends offers synchronous, asynchronous and snap-assisted replication, thin provisioning , high-availability grouping and advanced caching. Reliability and performance is the key for any storage server. StorTrends iTX 2.8 is designed to support Storage Bridge Bay specification that provide Auto- Failover capability to ensure that any interruption

4416-516: The Windows and DOS PC diagnostics programs. Later versions of AMIDiag support UEFI, which allows diagnostics to be performed directly on the hardware components, without having to use operating system drivers or facilities. AMI's UEFI firmware solutions. Aptio V is AMI's current main UEFI firmware product. Aptio CommunityEdition is an open source UEFI firmware product. Aptio 4 is a now-discontinued previous version that has been succeeded by Aptio V. MegaRAC

4508-438: The alphabets are usually written out in a large table , traditionally called a tableau . The tableau is usually 26×26, so that 26 full ciphertext alphabets are available. The method of filling the tableau, and of choosing which alphabet to use next, defines the particular polyalphabetic cipher. All such ciphers are easier to break than once believed, as substitution alphabets are repeated for sufficiently large plaintexts. One of

4600-408: The calculation of the length of the keyword in a Vigenère ciphered message. Once this was done, ciphertext letters that had been enciphered under the same alphabet could be picked out and attacked separately as a number of semi-independent simple substitutions - complicated by the fact that within one alphabet letters were separated and did not form complete words, but simplified by the fact that usually

4692-404: The code portion was restricted to the names of important people, hence the name of the cipher; in later years, it covered many common words and place names as well. The symbols for whole words ( codewords in modern parlance) and letters ( cipher in modern parlance) were not distinguished in the ciphertext. The Rossignols ' Great Cipher used by Louis XIV of France was one. Nomenclators were

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4784-527: The company published two books on its BIOS in 1993 and 1994, written by its engineers. During powerup, the BIOS firmware displays an ID string in the lower-left-hand corner of the screen. This ID string comprises various pieces of information about the firmware, including when it was compiled, what configuration options were selected, the OEM license code, and the targeted chipset and motherboard. There are 3 ID string formats,

4876-425: The crucial electronic components of a system, such as the central processing unit (CPU) and memory , and provides connectors for other peripherals . Unlike a backplane , a motherboard usually contains significant sub-systems, such as the central processor, the chipset 's input/output and memory controllers, interface connectors, and other components integrated for general use. Motherboard means specifically

4968-489: The earlier work of Ibn al-Durayhim (1312–1359), contained the first published discussion of the substitution and transposition of ciphers, as well as the first description of a polyalphabetic cipher, in which each plaintext letter is assigned more than one substitute. Polyalphabetic substitution ciphers were later described in 1467 by Leone Battista Alberti in the form of disks. Johannes Trithemius , in his book Steganographia ( Ancient Greek for "hidden writing") introduced

5060-455: The earliest known example of a homophonic substitution cipher in 1401 for correspondence with one Simone de Crema. Mary, Queen of Scots , while imprisoned by Elizabeth I, during the years from 1578 to 1584 used homophonic ciphers with additional encryption using a nomenclator for frequent prefixes, suffixes, and proper names while communicating with her allies including Michel de Castelnau . The work of Al-Qalqashandi (1355-1418), based on

5152-462: The encrypted form of that letter. Since many words in the Declaration of Independence start with the same letter, the encryption of that character could be any of the numbers associated with the words in the Declaration of Independence that start with that letter. Deciphering the encrypted text character X (which is a number) is as simple as looking up the Xth word of the Declaration of Independence and using

5244-564: The executive vice-president of this company. This partnership continued until 2001, when LSI Logic purchased the RAID Division of American Megatrends; American Megatrends then purchased all shares of the company owned by Sarma, making Shankar the majority owner. AMIDiag is a family of PC diagnostic utilities sold to OEMs only. The AMIDiag Suite was introduced in 1991 and made available for MS-DOS , Microsoft Windows and Unified Extensible Firmware Interface ( UEFI ) platforms. It includes both

5336-414: The exemplars, many motherboards offered additional performance or other features and were used to upgrade the manufacturer's original equipment. During the late 1980s and early 1990s, it became economical to move an increasing number of peripheral functions onto the motherboard. In the late 1980s, personal computer motherboards began to include single ICs (also called Super I/O chips) capable of supporting

5428-472: The first for older AMIBIOS, and the second and third for the newer AMI Hi-Flex ("high flexibility") BIOS. These latter are displayed when the Insert key is pressed during power-on self-test. The original AMI BIOS did not encrypt the machine startup password, which it stored in non-volatile RAM. Therefore, any utility capable of reading a PC's NVRAM was able to read and to alter the password. The AMI WinBIOS encrypts

5520-475: The first letter of that word as the decrypted character. Another homophonic cipher was described by Stahl and was one of the first attempts to provide for computer security of data systems in computers through encryption. Stahl constructed the cipher in such a way that the number of homophones for a given character was in proportion to the frequency of the character, thus making frequency analysis much more difficult. Francesco I Gonzaga , Duke of Mantua , used

5612-485: The fourth under 'C' again, and so on, or if the keyword is 'RISE', the first letter of plaintext is enciphered under alphabet 'R', the second under 'I', the third under 'S', the fourth under 'E', and so on. In practice, Vigenère keys were often phrases several words long. In 1863, Friedrich Kasiski published a method (probably discovered secretly and independently before the Crimean War by Charles Babbage ) which enabled

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5704-546: The huge number of possible combinations resulting from the rotation of several letter disks. Since one or more of the disks rotated mechanically with each plaintext letter enciphered, the number of alphabets used was astronomical. Early versions of these machine were, nevertheless, breakable. William F. Friedman of the US Army's SIS early found vulnerabilities in Hebern's rotor machine , and GC&CS 's Dillwyn Knox solved versions of

5796-529: The keyword " grandmother " gives us the following alphabets: The same message enciphers to Usually the ciphertext is written out in blocks of fixed length, omitting punctuation and spaces; this is done to disguise word boundaries from the plaintext and to help avoid transmission errors. These blocks are called "groups", and sometimes a "group count" (i.e. the number of groups) is given as an additional check. Five-letter groups are often used, dating from when messages used to be transmitted by telegraph : If

5888-483: The late 1940s. In its most common implementation, the one-time pad can be called a substitution cipher only from an unusual perspective; typically, the plaintext letter is combined (not substituted) in some manner (e.g., XOR ) with the key material character at that position. The one-time pad is, in most cases, impractical as it requires that the key material be as long as the plaintext, actually random , used once and only once, and kept entirely secret from all except

5980-456: The late 1990s; since then, most have required CPU fans mounted on heat sinks , due to rising clock speeds and power consumption. Most motherboards have connectors for additional computer fans and integrated temperature sensors to detect motherboard and CPU temperatures and controllable fan connectors which the BIOS or operating system can use to regulate fan speed. Alternatively computers can use

6072-400: The length of the message happens not to be divisible by five, it may be padded at the end with " nulls ". These can be any characters that decrypt to obvious nonsense, so that the receiver can easily spot them and discard them. The ciphertext alphabet is sometimes different from the plaintext alphabet; for example, in the pigpen cipher , the ciphertext consists of a set of symbols derived from

6164-461: The most popular was that of Blaise de Vigenère . First published in 1585, it was considered unbreakable until 1863, and indeed was commonly called le chiffre indéchiffrable ( French for "indecipherable cipher"). In the Vigenère cipher , the first row of the tableau is filled out with a copy of the plaintext alphabet, and successive rows are simply shifted one place to the left. (Such a simple tableau

6256-433: The motherboard cooling and monitoring solutions are usually based on a super I/O chip or an embedded controller . Motherboards contain a ROM (and later EPROM , EEPROM , NOR flash ) that stores firmware that initializes hardware devices and boots an operating system from a peripheral device . The terms bootstrapping and boot come from the phrase "lifting yourself by your bootstraps". Microcomputers such as

6348-419: The motherboard. Other components such as external storage , controllers for video display and sound , and peripheral devices may be attached to the motherboard as plug-in cards or via cables; in modern microcomputers, it is increasingly common to integrate some of these peripherals into the motherboard itself. An important component of a motherboard is the microprocessor's supporting chipset , which provides

6440-400: The now more standard form of a tableau (see below; ca. 1500 but not published until much later). A more sophisticated version using mixed alphabets was described in 1563 by Giovanni Battista della Porta in his book, De Furtivis Literarum Notis ( Latin for "On concealed characters in writing"). In a polyalphabetic cipher, multiple cipher alphabets are used. To facilitate encryption, all

6532-443: The other hand, use solid capacitors exclusively. For every 10 °C less, their average lifespan is multiplied approximately by three, resulting in a 6-times higher lifetime expectancy at 65 °C (149 °F). These capacitors may be rated for 5000, 10000 or 12000 hours of operation at 105 °C (221 °F), extending the projected lifetime in comparison with standard solid capacitors. In desktop PCs and notebook computers,

6624-551: The pattern of their letters; for example, the English words tater , ninth , and paper all have the pattern ABACD . Many people solve such ciphers for recreation, as with cryptogram puzzles in the newspaper. According to the unicity distance of English , 27.6 letters of ciphertext are required to crack a mixed alphabet simple substitution. In practice, typically about 50 letters are needed, although some messages can be broken with fewer if unusual patterns are found. In other cases,

6716-481: The plaintext can be contrived to have a nearly flat frequency distribution, and much longer plaintexts will then be required by the cryptanalyst. One once-common variant of the substitution cipher is the nomenclator . Named after the public official who announced the titles of visiting dignitaries, this cipher uses a small code sheet containing letter, syllable and word substitution tables, sometimes homophonic, that typically converted symbols into numbers. Originally

6808-406: The same family will fit larger cases. For example, an ATX case will usually accommodate a microATX motherboard. Laptop computers generally use highly integrated, miniaturized, and customized motherboards. This is one of the reasons that laptop computers are difficult to upgrade and expensive to repair. Often the failure of one laptop component requires the replacement of the entire motherboard, which

6900-497: The same time, and rotor cipher machines were patented four times in 1919. The most important of the resulting machines was the Enigma , especially in the versions used by the German military from approximately 1930. The Allies also developed and used rotor machines (e.g., SIGABA and Typex ). All of these were similar in that the substituted letter was chosen electrically from amongst

6992-419: The sender and intended receiver. When these conditions are violated, even marginally, the one-time pad is no longer unbreakable. Soviet one-time pad messages sent from the US for a brief time during World War II used non-random key material. US cryptanalysts, beginning in the late 40s, were able to, entirely or partially, break a few thousand messages out of several hundred thousand. (See Venona project ) In

7084-448: The simplest is to use a numeric substitution 'alphabet'. Another method consists of simple variations on the existing alphabet; uppercase, lowercase, upside down, etc. More artistically, though not necessarily more securely, some homophonic ciphers employed wholly invented alphabets of fanciful symbols. The book cipher is a type of homophonic cipher, one example being the Beale ciphers . This

7176-419: The standard fare of diplomatic correspondence, espionage , and advanced political conspiracy from the early fifteenth century to the late eighteenth century; most conspirators were and have remained less cryptographically sophisticated. Although government intelligence cryptanalysts were systematically breaking nomenclators by the mid-sixteenth century, and superior systems had been available since 1467,

7268-578: The stored password, using a simple substitution cipher . By pressing the Delete key during power-on self-test when a prompt is displayed, the BIOS setup utility program is invoked. Some earlier AMIBIOS versions also included a cut-down version of the AMIDIAG utility that AMI also sold separately, but most later AMI BIOSes do not include this program as the BIOS DMI already incorporates detailed diagnostics. AMIBIOS

7360-405: The supporting interfaces between the CPU and the various buses and external components. This chipset determines, to an extent, the features and capabilities of the motherboard. Modern motherboards include: Additionally, nearly all motherboards include logic and connectors to support commonly used input devices, such as USB for mouse devices and keyboards . Early personal computers such as

7452-457: The time. WinBIOS was viewed favorably by Anand Lal Shimpi at AnandTech , but described by Thomas Pabst at Tom's Hardware as a "big disappointment", in part because of problems with distributing IRQ signals to every PCI and ISA expansion slot. In July 2008 Linux developers discovered issues with ACPI tables on certain AMIBIOS BIOSes supplied by Foxconn, ASUS, and MSI. The problem was related to

7544-431: The traditional keyword method for creating a mixed substitution alphabet is simple, a serious disadvantage is that the last letters of the alphabet (which are mostly low frequency) tend to stay at the end. A stronger way of constructing a mixed alphabet is to generate the substitution alphabet completely randomly. Although the number of possible substitution alphabets is very large (26! ≈ 2 , or about 88 bits ), this cipher

7636-436: The tune to " Happy Birthday ". The PC would remain halted, and the song would continue playing until a key was pressed, after which bootup would resume. The problem was caused by a virus-free Trojan , which was later resolved with firmware updates. The AMI WinBIOS was a 1994 update to AMIBIOS, with a graphical user interface setup screen that mimicked the appearance of Windows 3.1 and supported mouse navigation, unusual at

7728-507: The turn of the century (like the tablet computer and the netbook ). Memory, processors, network controllers, power source, and storage would be integrated into some systems. A motherboard provides the electrical connections by which the other components of the system communicate. Unlike a backplane, it also contains the central processing unit and hosts other subsystems and devices. A typical desktop computer has its microprocessor , main memory , and other essential components connected to

7820-433: The usual response to cryptanalysis was simply to make the tables larger. By the late eighteenth century, when the system was beginning to die out, some nomenclators had 50,000 symbols. Nevertheless, not all nomenclators were broken; today, cryptanalysis of archived ciphertexts remains a fruitful area of historical research . An early attempt to increase the difficulty of frequency analysis attacks on substitution ciphers

7912-535: Was discovered where some Baseboard Management Controllers were shipped with a license/royalty sticker that had the company name misspelled as "American Megatrands". Motherboard A motherboard (also called mainboard , main circuit board , MB , base board , system board , or, in Apple computers, logic board ) is the main printed circuit board (PCB) in general-purpose computers and other expandable systems. It holds and allows communication between many of

8004-460: Was formerly sold through distributors, not directly available from the manufacturer or from eSupport. AMI supplies both DOS and Windows firmware upgrade utilities for its own motherboards. eSupport only supplies a Windows upgrade utility. The StorTrends family of network-based backup and storage management software and hardware includes several NAS and iSCSI-based SAN servers with 4, 12, or 16 drive bays. AMI couples off-the-shelf hardware with

8096-483: Was founded in 1985 by Subramonian Shankar and Pat Sarma with funds from a previous consulting venture, Access Methods Inc. (also AMI). Access Methods was a company run by Pat Sarma and his partner. After Access Methods successfully launched the AMIBIOS, there were legal issues among the owners of the company, resulting in Sarma buying out his partners. Access Methods still owned the rights to the AMIBIOS. Sarma had already started

8188-425: Was given by Al-Kindi in A Manuscript on Deciphering Cryptographic Messages written around 850 CE. The method he described is now known as frequency analysis . Substitution of single letters separately— simple substitution —can be demonstrated by writing out the alphabet in some order to represent the substitution. This is termed a substitution alphabet . The cipher alphabet may be shifted or reversed (creating

8280-461: Was released in June 2014. The software is available for download for a free 30-day trial, and is available for purchase for a complete license. On March 7, 2018, American Megatrends officially announced that it ceased development of DuOS-M. No further updates were being released at this time, including bug fixes and security patches. On November 13, 1993, some PCs with AMIBIOS firmware began bootup playing

8372-676: Was shown to be the result of a faulty electrolyte formulation, an issue termed capacitor plague . Modern motherboards use electrolytic capacitors to filter the DC power distributed around the board. These capacitors age at a temperature-dependent rate, as their water based electrolytes slowly evaporate. This can lead to loss of capacitance and subsequent motherboard malfunctions due to voltage instabilities. While most capacitors are rated for 2000 hours of operation at 105 °C (221 °F), their expected design life roughly doubles for every 10 °C (18 °F) below this. At 65 °C (149 °F)

8464-474: Was to disguise plaintext letter frequencies by homophony . In these ciphers, plaintext letters map to more than one ciphertext symbol. Usually, the highest-frequency plaintext symbols are given more equivalents than lower frequency letters. In this way, the frequency distribution is flattened, making analysis more difficult. Since more than 26 characters will be required in the ciphertext alphabet, various solutions are employed to invent larger alphabets. Perhaps

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