A USB hub is a device that expands a single Universal Serial Bus port into several so that there are more ports available to connect devices to a host system, similar to a power strip. USB hubs are built into equipment such as computers, monitors, or printers; when such a device has many USB ports, they all stem from one or two internal USB hubs rather than each port having independent USB circuitry. Physically separate USB hubs come in a wide variety of form factors: from external boxes connectible with a long cable, to small designs that can be directly plugged into a USB port. In the middle case, there are "short cable" hubs which use an integral 6-inch cable to distance a small hub away from physical port congestion and of course increase the number of available ports. Laptop computers may be equipped with many USB ports, but an external USB hub can consolidate several everyday devices into a single hub to enable one-step attachment and removal of all the devices. A USB network is built from USB hubs connected downstream to USB ports, which themselves may stem from USB hubs.
USB hubs can extend a USB network to a maximum of 127 ports. The USB specification requires that bus-powered/passive hubs may not be connected in series to other bus-powered hubs. USB ports are closely spaced. Plugging a device into one port may physically block an adjacent port when the plug is not part of a cable but is integral to a device such as a USB flash drive. A horizontal array of horizontal sockets may be easy to fabricate, but may cause only two out of four ports to be usable. Port arrays in which the port orientation is perpendicular to the array orientation have fewer blockage problems. External "Octopus" or "Squid" hubs, or "star" hubs avoid this problem completely. USB cables are limited to 3 metres for low-speed USB 1.1 devices. A hub can be used as an active USB repeater to extend cable length for up to 5 metre lengths at a time. Active cables perform the same function, but since they are bus-powered, externally powered USB hubs would be required for some of the segments. A bus-powered hub is a hub.
It does not need a separate power connection. However, many devices require more power than this method can provide and will not work in this type of hub, it may be desirable to use a bus-powered hub with self-powered external hard-disk units, as they may not go into sleep mode upon computer shut-down or sleep mode when using a self-powered hub since they will continue to see a power source on the USB ports when using a self-powered hub. A USB's electric current is allocated in units of 100 mA up to a maximum total of 500 mA per port. Therefore, a compliant bus powered hub can have no more than four downstream ports and cannot offer more than four 100 mA units of current in total to downstream devices. If a device requires more units of current than the port it is plugged into can supply, the operating system reports this to the user. In contrast, a self-powered hub is one that takes its power from an external power supply unit and can therefore provide full power to every port. Many hubs can operate as self powered hubs.
However, there are many non-compliant hubs on the market which announce themselves to the host as self-powered despite being bus-powered. There are plenty of non-compliant devices that use more than 100 mA without announcing this fact; these hubs and devices do allow more flexibility in the use of power, but they are to make power problems harder to diagnose. Some self-powered hubs do not supply enough power to drive a 500 mA load on every port. For example, many seven port hubs have a 1A power supply, when in fact seven ports could draw a maximum of 7 x 0.5 = 3.5A, plus power for the hub itself. Designers assume the user will most connect many low power devices and only one or two requiring a full 500 mA. On the other hand, the packaging for some self-powered hubs states explicitly how many of the ports can drive a 500 mA full load at once. For example, the packaging on a seven-port hub might claim to support a maximum of four full-load devices. Dynamic-powered hubs are hubs, they can automatically switch between modes depending on whether a separate power supply is available or not.
While switching from bus-powered to self-powered operation does not require immediate renegotiations with the host, switching from self-powered to bus-powered operation may cause USB connections to be reset if connected devices requested more power than still available in bus-powered mode. To allow high-speed devices to operate in their fastest mode, all hubs between the devices and the computer must be high-speed. High-speed devices should fall back to full-speed. While high-speed hubs can communicate at all device speeds, low- and full-speed traffic is combined and segregated from high-speed traffic through a transaction translator; each tran
A wireless router is a device that performs the functions of a router and includes the functions of a wireless access point. It is used to provide access to a private computer network. Depending on the manufacturer and model, it can function in a wired local area network, in a wireless-only LAN, or in a mixed wired and wireless network. Most current wireless routers have the following characteristics: One or multiple NICs supporting Fast Ethernet or Gigabit Ethernet integrated into the main SoC; some newer routers feature Link Aggregation allowing two ports to be used together improving throughput and redundancy. One or multiple WNICs supporting a part of the IEEE 802.11-standard family integrated into the main SoC or as separate chips on the printed circuit board. It can be a distinct card connected over a MiniPCI or MiniPCIe interface. So far the PHY-Chips for the WNICs are distinct chips on the PCB. Dependent on the mode the WNIC supports, i.e. 1T1R, 2T2R or 3T3R, one WNIC have up to 3 PHY-Chips connected to it.
Each PHY-Chip is connected to a Hirose U. FL-connector on the PCB. A so-called pigtail cable connects the Hirose U. FL either to a RF connector, in which case the antenna can be changed or directly to the antenna, in which case it is integrated into the casing. Common are dual-band and tri-band antennas. An Ethernet switch supporting Gigabit Ethernet or Fast Ethernet, with support for IEEE 802.1Q, integrated into the main SoC or as separate Chip on the PCB. Some wireless routers come with either xDSL modem, DOCSIS modem, LTE modem, or fiber optic modem integrated. IEEE 802.11 ac ready. Some dual-band wireless routers operate 5 GHz bands simultaneously. Many dual-band wireless routers have data transfer rates exceeding 450 Mbit/s; some wireless routers provide. The Wi-Fi clone button simplifies Wi-Fi configuration and builds a seamless unified home network, enabling Super Range Extension, which means it can automatically copy the SSID and Password of your router; some wireless routers have two USB ports.
For wireless routers having one USB port, it is designated for either printer or desktop/mobile external hard disk drive. For wireless routers having two USB ports, one is designated for the printer and the other one is designated for either desktop or mobile external hard disk drive; some wireless routers have a USB port designed for connecting mobile broadband modem, aside from connecting the wireless router to an Ethernet with xDSL or cable modem. A mobile broadband USB adapter can be connected to the router to share the mobile broadband Internet connection through the wireless network. There are many wireless data standards. New standards have been created to accommodate the increasing need for faster wireless connections; some wireless routers provide backward compatibility with older Wi-Fi technologies as many devices were manufactured for use with older standards. The most common operating system on such embedded devices is Linux. More seldomly, VxWorks is used; the devices are configured over a web user interface served by a light web server software running on the device.
It is possible for a computer running a desktop operating system with appropriate software to act as a wireless router. This is referred to as a SoftAP. In 2003, Linksys was forced to open-source the firmware of its WRT54G router series after people on the Linux kernel mailing list discovered that it used GPL Linux code. In 2008, Cisco was sued in Free Software Foundation, Inc. v. Cisco Systems, Inc due to similar issues with Linksys routers. Since various open-source projects have built on this foundation, including OpenWrt, DD-WRT, Tomato. In 2016, various manufacturers changed their firmware to block custom installations after an FCC ruling. However, some companies plan to continue to support open-source firmware, including Linksys and Asus. HomePlug AV Wi-Fi Protected Setup
Marvell Technology Group
Marvell Technology Group, Limited, is a producer of storage and consumer semiconductor products. The company has over 3,700 employees. Marvell's U. S. operating headquarters is located in Santa Clara and the company operates design centers in Europe, India and China. Marvell is a "fabless" manufacturer of semiconductors that ships more than one billion integrated circuits per year, its market segments include data center, enterprise / campus, automotive and home / consumer. Marvell was founded in 1995 by Sehat Sutardja, his wife Weili Dai, brother Pantas Sutardja; the initial public offering on June 27, 2000 raised $90 million, with the stock listed on NASDAQ with the symbol MRVL. After raising from $19 to over $63 per share, three days it was $55.25. At the time, the five largest customers, Samsung Electronics, Seagate Technology and Toshiba, accounted for 97% of sales; the shares dropped in December when insiders were allowed to sell. In July 2018, Marvell completed its acquisition of Cavium, Inc. strengthening its storage, networking, wireless connectivity and security product portfolios for the infrastructure market.
On the same day, Marvell announced the appointment of Syed Ali, Brad Buss and Dr. Edward Frank to the Marvell Board of Directors. In the summer of 2018, Marvell became the first silicon vendor in North America to open a CISPR 25 qualified automotive electromagnetic compatibility lab with the in-house capability to perform a wide range of emission, immunity and ESD tests to further drive the development of industry-leading automotive connectivity solutions; the company is headquartered in Hamilton, Bermuda. The US operations known as Marvell Semiconductor, are located in Silicon Valley, California. Through the years, Marvell acquired smaller companies to enter new markets. Marvell's first products were sold for computer data storage devices. In March 2000, computer networking products for the Ethernet family were first shipped. In October 2002, the Yukon brand Gigabit Ethernet controller was announced. On June 27, 2006, the sale of Intel's XScale assets was announced. Intel agreed to sell the XScale business to Marvell for an estimated USD 600 million in cash and the assumption of unspecified liabilities.
The acquisition was completed on November 9, 2006. In 2009, Marvell announced that the SheevaPlug, a small, low-power, SoC-based ARM architecture computer, would be released with full schematics. Marvell supplied the Wi-Fi chip for the original Apple iPhone. Marvell Mobile Hotspot is an in-car Wi-Fi connectivity; the 2010 Audi A8 was the first automobile in the market to feature a factory-installed MMH. Google's Chromecast products are powered by Marvell SoCs. Namely the Marvell ARMADA 1500 Mini SoC for the Chromecast 1st gen and Marvell ARMADA 1500 Mini Plus SoC for the Chromecast 2nd gen & Chromecast audio. Synaptics acquired Marvell Multimedia Solutions on 2017-06-12 ARMADA 1500 SoC's are now produced under different names In 2012, Marvell was named one of Thomson Reuters top 100 global innovators. In 2006, the US Securities and Exchange Commission started an inquiry on the company's stock option grant practices. An investigation determined "grant dates were chosen with the benefit of hindsight" to make the options more valuable.
The press estimated that the founders and other executives had made $760 million in gains from the options, which were awarded by the founding couple, Sehat Sutardja and Weili Dai. The SEC asked to interview the company general counsel Matthew Gloss, but Marvell claimed attorney-client privilege. Gloss was fired just before the investigation results were announced in May 2007. Abraham David Sofaer was hired to investigate the investigation after Gloss alleged it was not independent. In announcing the results of its own inquiry, the SEC did not give Marvell the credit granted other companies in the options scandal for cooperating with the SEC’s investigation or for cleaning up. At the time of the announcement, the co-acting regional director of the SEC’s San Francisco office stated, among other things, that the SEC did not believe that the lack of cooperation and remediation shown by Marvell merited a whole lot of credit in terms of giving Marvell a break. In announcing its results, the SEC found that Gloss was not a participant in Dai and Sutardja’s backdating scheme.
Marvell restated its financial results, stated that Dai will no longer be executive vice president, chief operating officer, a director but continue with the company in a non-management position. The company agreed to pay a $10 million fine in 2008, but did not fire Dai nor replace Sutardja as chairman as stated by the investigating committee. In December 2012, a Pittsburgh jury ruled that Marvell had infringed two patents by incorporating hard disk technology developed and owned by Carnegie Mellon University without a license; the technology, relating to improving hard disk data read accuracy at high speeds, was reported to have been used in 2.3 billion chips sold by Marvell between 2003 and 2012. The jury awarded damages of $1.17 billion, the third largest in a patent case at the time. The jury found that the breach had been "willful", giving the judge discretion to award up to three times the original damage amount. In December 2
Apple Inc. is an American multinational technology company headquartered in Cupertino, that designs and sells consumer electronics, computer software, online services. It is considered one of the Big Four of technology along with Amazon and Facebook; the company's hardware products include the iPhone smartphone, the iPad tablet computer, the Mac personal computer, the iPod portable media player, the Apple Watch smartwatch, the Apple TV digital media player, the HomePod smart speaker. Apple's software includes the macOS and iOS operating systems, the iTunes media player, the Safari web browser, the iLife and iWork creativity and productivity suites, as well as professional applications like Final Cut Pro, Logic Pro, Xcode, its online services include the iTunes Store, the iOS App Store, Mac App Store, Apple Music, Apple TV+, iMessage, iCloud. Other services include Apple Store, Genius Bar, AppleCare, Apple Pay, Apple Pay Cash, Apple Card. Apple was founded by Steve Jobs, Steve Wozniak, Ronald Wayne in April 1976 to develop and sell Wozniak's Apple I personal computer, though Wayne sold his share back within 12 days.
It was incorporated as Apple Computer, Inc. in January 1977, sales of its computers, including the Apple II, grew quickly. Within a few years and Wozniak had hired a staff of computer designers and had a production line. Apple went public in 1980 to instant financial success. Over the next few years, Apple shipped new computers featuring innovative graphical user interfaces, such as the original Macintosh in 1984, Apple's marketing advertisements for its products received widespread critical acclaim. However, the high price of its products and limited application library caused problems, as did power struggles between executives. In 1985, Wozniak departed Apple amicably and remained an honorary employee, while Jobs and others resigned to found NeXT; as the market for personal computers expanded and evolved through the 1990s, Apple lost market share to the lower-priced duopoly of Microsoft Windows on Intel PC clones. The board recruited CEO Gil Amelio to what would be a 500-day charge for him to rehabilitate the financially troubled company—reshaping it with layoffs, executive restructuring, product focus.
In 1997, he led Apple to buy NeXT, solving the failed operating system strategy and bringing Jobs back. Jobs pensively regained leadership status, becoming CEO in 2000. Apple swiftly returned to profitability under the revitalizing Think different campaign, as he rebuilt Apple's status by launching the iMac in 1998, opening the retail chain of Apple Stores in 2001, acquiring numerous companies to broaden the software portfolio. In January 2007, Jobs renamed the company Apple Inc. reflecting its shifted focus toward consumer electronics, launched the iPhone to great critical acclaim and financial success. In August 2011, Jobs resigned as CEO due to health complications, Tim Cook became the new CEO. Two months Jobs died, marking the end of an era for the company. Apple is well known for its size and revenues, its worldwide annual revenue totaled $265 billion for the 2018 fiscal year. Apple is the world's largest information technology company by revenue and the world's third-largest mobile phone manufacturer after Samsung and Huawei.
In August 2018, Apple became the first public U. S. company to be valued at over $1 trillion. The company employs 123,000 full-time employees and maintains 504 retail stores in 24 countries as of 2018, it operates the iTunes Store, the world's largest music retailer. As of January 2018, more than 1.3 billion Apple products are in use worldwide. The company has a high level of brand loyalty and is ranked as the world's most valuable brand. However, Apple receives significant criticism regarding the labor practices of its contractors, its environmental practices and unethical business practices, including anti-competitive behavior, as well as the origins of source materials. Apple Computer Company was founded on April 1, 1976, by Steve Jobs, Steve Wozniak, Ronald Wayne; the company's first product is the Apple I, a computer designed and hand-built by Wozniak, first shown to the public at the Homebrew Computer Club. Apple I was sold as a motherboard —a base kit concept which would now not be marketed as a complete personal computer.
The Apple I went on sale in July 1976 and was market-priced at $666.66. Apple Computer, Inc. was incorporated on January 3, 1977, without Wayne, who had left and sold his share of the company back to Jobs and Wozniak for $800 only twelve days after having co-founded Apple. Multimillionaire Mike Markkula provided essential business expertise and funding of $250,000 during the incorporation of Apple. During the first five years of operations revenues grew exponentially, doubling about every four months. Between September 1977 and September 1980, yearly sales grew from $775,000 to $118 million, an average annual growth rate of 533%; the Apple II invented by Wozniak, was introduced on April 16, 1977, at the first West Coast Computer Faire. It differs from its major rivals, the TRS-80 and Commodore PET, because of its character cell-based color graphics and open architecture. While early Apple II models use ordinary cassette tapes as storage devices, they were superseded by the introduction of a 5 1⁄4-inch floppy disk drive and interface called the Disk II.
The Apple II was chosen to be the desktop platform for the first "killer app" of the business world: VisiCalc, a spreadsheet program. VisiCalc created a business market for the Apple II and gave home users an additional reason to buy an Apple II: compatibility with the office. Before VisiCalc, Apple had been a distant third place c
AC power plugs and sockets
AC power plugs and sockets connect electric equipment to the alternating current power supply in buildings and at other sites. Electrical plugs and sockets differ from one another in voltage and current rating, shape and connector type. Different standard systems of plugs and sockets are used around the world. Plugs and sockets for portable appliances became available in the 1880s, to replace connections to light sockets with wall-mounted outlets. A proliferation of types developed for both protection from electrical injury. Today there are about 20 types in common use around the world, many obsolete socket types are found in older buildings. Coordination of technical standards has allowed some types of plug to be used across large regions to facilitate trade in electrical appliances, for the convenience of travellers and consumers of imported electrical goods; some multi-standard sockets allow use of several types of plug. A plug is the movable connector attached to an electrically operated device, the socket is fixed on equipment or a building structure and connected to an energised electrical circuit.
The plug is a male connector with protruding pins that match the openings and female contacts in a socket. Some plugs have female contacts; some plugs have built-in fuses for safety. To reduce the risk of electric shock and socket systems have safety features in addition to the recessed contacts of the energised socket; these may include plugs with insulated sleeves, recessed sockets, or automatic shutters to block socket apertures when a plug is removed. A socket may be surrounded by a decorative or protective cover which may be integral with the socket. Single-phase sockets have two current-carrying connections to the power supply circuit, may have a third pin for a safety connection to earth ground. Depending on the supply system, one or both current-carrying connections may have significant voltage to earth ground; when commercial electric power was first introduced in the 1880s, it was used for lighting. Other portable appliances were connected to light-bulb sockets; as early as 1885 a two-pin plug and wall socket format was available on the British market.
By about 1910 the first three-pin earthed. Over time other safety improvements were introduced to the market; the earliest national standard for plug and wall socket forms was set in 1915. Designs of plugs and sockets have developed to reduce the risk of electric shock and fire. Plugs are shaped to prevent finger contact with live parts, sockets may be recessed; some types can include fuses and switches. Shutters on the socket prevents foreign objects from contacting live contacts; the first shuttered socket was introduced by British manufacturer Crompton, in 1893. Electrical insulation of the pin shanks to reduce live contact exposure was added to some designs, as early as 1905. A third contact for a connection to earth is intended to protect against insulation failure of the connected device; some early unearthed plug and socket types were revised to include an earthing pin or phased out in favour of earthed types. The plug is designed so that the earth ground contact connects before the energized circuit contacts.
The assigned IEC appliance classis governed by the requirement for earthing or equivalent protection. Class I equipment requires an earth contact in the plug and socket, while Class II equipment is unearthed and protects the user with double insulation. Where a "neutral" conductor exists in supply wiring, polarization of the plug can improve safety by preserving the distinction in the equipment. For example, appliances may ensure that switches interrupt the line side of the circuit, or can connect the shell of a screw-base lampholder to neutral to reduce electric shock hazard. In some designs, polarized plugs cannot be mated with non-polarized sockets. Wiring systems where both circuit conductors have a significant potential with respect to earth do not benefit from polarized plugs. "Universal" or "multi-standard" sockets are intended to accommodate plugs of various types. In some jurisdictions, they violate safety standards for sockets. Safety advocates, the United States Army, a manufacturer of sockets point out a number of safety issues with universal socket and adapters, including voltage mismatch, exposure of live pins, lack of proper earth ground connection, or lack of protection from overload or short circuit.
Universal sockets may not meet technical standards for durability, plug retention force, temperature rise of components, or other performance requirements, as they are outside the scope of national and international technical standards. A technical standard may include compatibility of a socket with more than one form of plug; the Thai dual socket is specified in figure 4 of TIS 166-2549 and is designed to accept Thai plugs, Type A, B and C plugs. Chinese dual sockets have both an unearthed socket complying with figure 5 of GB 1002-2008, an earthed socket complying with figure 4 of GB 1002-2008; the exception is that both Thai and Chinese dual sockets accept 120 V rated plugs causing an electrical incompatibility because both states use a 220 V residential voltage. Plugs and power cords have a rated current assigned to them by the manufacturer. Using a plug or power cord, inappropriate for the load may be a safety hazard. For example, high-current equipment can cause a f
In information technology, a backup, or data backup, or the process of backing up, refers to the copying into an archive file of computer data, in secondary storage—so that it may be used to restore the original after a data loss event. The verb form is "back up", whereas the noun and adjective form is "backup". Backups have two distinct purposes; the primary purpose is to be it by data deletion or corruption. Data loss can be a common experience of computer users; the secondary purpose of backups is to recover data from an earlier time, according to a user-defined data retention policy configured within a backup application for how long copies of data are required. Though backups represent a simple form of disaster recovery and should be part of any disaster recovery plan, backups by themselves should not be considered a complete disaster recovery plan. One reason for this is that not all backup systems are able to reconstitute a computer system or other complex configuration such as a computer cluster, active directory server, or database server by restoring data from a backup.
Since a backup system contains at least one copy of all data considered worth saving, the data storage requirements can be significant. Organizing this storage space and managing the backup process can be a complicated undertaking. A data repository model may be used to provide structure to the storage. Nowadays, there are many different types of data storage devices. There are many different ways in which these devices can be arranged to provide geographic redundancy, data security, portability. Before data are sent to their storage locations, they are selected and manipulated. Many different techniques have been developed to optimize the backup procedure; these include optimizations for dealing with open files and live data sources as well as compression, de-duplication, among others. Every backup scheme should include dry runs that validate the reliability of the data being backed up, it is important to recognize human factors involved in any backup scheme. Any backup strategy starts with a concept of a data repository.
The backup data needs to be stored, should be organized to a degree. The organisation could be as simple as a sheet of paper with a list of all backup media and the dates they were produced. A more sophisticated setup could include catalog, or relational database. Different approaches have different advantages. Part of the model is the backup rotation scheme. Unstructured An unstructured repository may be a stack of tapes or CD-Rs or DVD-Rs with minimal information about what was backed up and when; this is the easiest to implement, but the least to achieve a high level of recoverability as it lacks automation. Full only / System imaging A repository of this type contains complete system images taken at one or more specific points in time; this technology is used by computer technicians to record known good configurations. Imaging is more useful for deploying a standard configuration to many systems rather than as a tool for making ongoing backups of diverse systems. Incremental An incremental style repository aims to make it more feasible to store backups from more points in time by organizing the data into increments of change between points in time.
This eliminates the need to store duplicate copies of unchanged data: with full backups a lot of the data will be unchanged from what has been backed up previously. A full backup is made on one occasion and serves as the reference point for an incremental backup set. After that, a number of incremental backups are made after successive time periods. Restoring the whole system to the date of the last incremental backup would require starting from the last full backup taken before the data loss, applying in turn each of the incremental backups since then. Additionally, some backup systems can reorganize the repository to synthesize full backups from a series of incrementals. Differential Each differential backup saves the data, it has the advantage. One disadvantage, compared to the incremental backup method, is that as time from the last full backup increases, so does the time to perform the differential backup. Restoring an entire system would require starting from the most recent full backup and applying just the last differential backup since the last full backup.
By standard definition, a differential backup copies files that have been created or changed since the last full backup, regardless of whether any other differential backups have been made since whereas an incremental backup copies files that have been created or changed since the most recent backup of any type. Other variations of incremental backup include multi-level incrementals and incremental backups that compare parts of files instead of just the whole file. Reverse delta A reverse delta type repository stores a recent "mirror" of the source data and a series of differences between the mirror in its current state and its previous states. A reverse delta backup will start with a normal full backup. After the full backup is performed, the system will periodically synchronize the full backup with the live copy, wh
United States dollar
The United States dollar is the official currency of the United States and its territories per the United States Constitution since 1792. In practice, the dollar is divided into 100 smaller cent units, but is divided into 1000 mills for accounting; the circulating paper money consists of Federal Reserve Notes that are denominated in United States dollars. Since the suspension in 1971 of convertibility of paper U. S. currency into any precious metal, the U. S. dollar is, de facto, fiat money. As it is the most used in international transactions, the U. S. dollar is the world's primary reserve currency. Several countries use it as their official currency, in many others it is the de facto currency. Besides the United States, it is used as the sole currency in two British Overseas Territories in the Caribbean: the British Virgin Islands and Turks and Caicos Islands. A few countries use the Federal Reserve Notes for paper money, while still minting their own coins, or accept U. S. dollar coins. As of June 27, 2018, there are $1.67 trillion in circulation, of which $1.62 trillion is in Federal Reserve notes.
Article I, Section 8 of the U. S. Constitution provides that the Congress has the power "To coin money". Laws implementing this power are codified at 31 U. S. C. § 5112. Section 5112 prescribes the forms; these coins are both designated in Section 5112 as "legal tender" in payment of debts. The Sacagawea dollar is one example of the copper alloy dollar; the pure silver dollar is known as the American Silver Eagle. Section 5112 provides for the minting and issuance of other coins, which have values ranging from one cent to 100 dollars; these other coins are more described in Coins of the United States dollar. The Constitution provides that "a regular Statement and Account of the Receipts and Expenditures of all public Money shall be published from time to time"; that provision of the Constitution is made specific by Section 331 of Title 31 of the United States Code. The sums of money reported in the "Statements" are being expressed in U. S. dollars. The U. S. dollar may therefore be described as the unit of account of the United States.
The word "dollar" is one of the words in the first paragraph of Section 9 of Article I of the Constitution. There, "dollars" is a reference to the Spanish milled dollar, a coin that had a monetary value of 8 Spanish units of currency, or reales. In 1792 the U. S. Congress passed a Coinage Act. Section 9 of that act authorized the production of various coins, including "DOLLARS OR UNITS—each to be of the value of a Spanish milled dollar as the same is now current, to contain three hundred and seventy-one grains and four sixteenth parts of a grain of pure, or four hundred and sixteen grains of standard silver". Section 20 of the act provided, "That the money of account of the United States shall be expressed in dollars, or units... and that all accounts in the public offices and all proceedings in the courts of the United States shall be kept and had in conformity to this regulation". In other words, this act designated the United States dollar as the unit of currency of the United States. Unlike the Spanish milled dollar, the U.
S. dollar is based upon a decimal system of values. In addition to the dollar the coinage act established monetary units of mill or one-thousandth of a dollar, cent or one-hundredth of a dollar, dime or one-tenth of a dollar, eagle or ten dollars, with prescribed weights and composition of gold, silver, or copper for each, it was proposed in the mid-1800s that one hundred dollars be known as a union, but no union coins were struck and only patterns for the $50 half union exist. However, only cents are in everyday use as divisions of the dollar. XX9 per gallon, e.g. $3.599, more written as $3.599⁄10. When issued in circulating form, denominations equal to or less than a dollar are emitted as U. S. coins while denominations equal to or greater than a dollar are emitted as Federal Reserve notes. Both one-dollar coins and notes are produced today, although the note form is more common. In the past, "paper money" was issued in denominations less than a dollar and gold coins were issued for circulation up to the value of $20.
The term eagle was used in the Coinage Act of 1792 for the denomination of ten dollars, subsequently was used in naming gold coins. Paper currency less than one dollar in denomination, known as "fractional currency", was sometimes pejoratively referred to as "shinplasters". In 1854, James Guthrie Secretary of the Treasury, proposed creating $100, $50 and $25 gold coins, which were referred to as a "Union", "Half Union", "Quarter Union", thus implying a denomination of 1 Union = $100. Today, USD notes are made from cotton fiber paper, unlike most common paper, made of wood fiber. U. S. coins are produced by the United States Mint. U. S. dollar banknotes are printed by the Bureau of Engraving and Printing and, since 1914, have been issued by t