Uno
Uno is a proprietary shedding-type card game for 2 to 10 players, originally invented in 1971 by Merle Robbins, a barber from Reading, Ohio, in which participants match cards from their hands to a central discard pile by color, number, or symbol, incorporating action cards that impose penalties like drawing extra cards or skipping turns, with the objective of being the first to empty one's hand while announcing "Uno" upon playing the penultimate card.[1][2] Robbins devised the game to arbitrate a rules dispute among family members during a session of Crazy Eights, prompting him and his wife Marie to self-produce 5,000 decks for manual distribution across the Midwest before selling the rights to International Games Inc. in 1972 for $50,000 plus royalties.[3][2] The standard deck comprises 108 cards across four colors (red, blue, green, yellow), featuring numbered cards from 0 to 9 (with duplicates except for zeros), plus action cards such as Skip, Reverse, Draw Two, Wild, and Wild Draw Four, alongside customizable blank cards in some editions.[4] Gameplay proceeds clockwise by default, with players drawing from the deck if unable to match, and scoring based on opponents' remaining cards upon a win, typically targeting 500 points across multiple rounds.[1] Acquired by Mattel in 1992 following International Games' expansion, Uno has sustained commercial dominance through iterative variants like Uno Attack and themed editions, evolving into a global franchise with digital adaptations and merchandise while retaining core mechanics that emphasize rapid decisions and strategic penalty avoidance.[3][5]Card Game
Invention and Early History
Merle Robbins, a barber from Reading, Ohio, invented Uno in 1971 at the age of 59 to resolve a family dispute over the rules of Crazy Eights, a similar shedding-type card game.[6] [7] Robbins hand-crafted the initial deck by modifying a standard deck and inscribing specific action rules directly onto the cards using a felt-tipped pen, establishing the game's core mechanics of matching colors or numbers while incorporating penalty and reversal effects.[2] Recognizing the game's potential, Robbins and his family formed International Games, Inc. in 1971 to produce and distribute Uno commercially.[8] They manufactured an initial run of 5,000 decks, which sold out, prompting an additional order of 10,000 units that Robbins and his son Ray personally marketed to local retailers.[9] The game's straightforward rules and broad appeal contributed to early word-of-mouth success, though production remained small-scale and family-operated in its nascent phase.[2] By 1981, facing growth challenges, Robbins sold the rights to Uno to a group of investors led by Robert Tezak, who had acquired International Games, Inc. and shifted operations to offices behind his funeral parlor in Milford, Ohio.[10] This transition marked the end of the Robbins family's direct involvement and laid the groundwork for broader commercialization, with early manufacturing handled by Saltzman Printers.[8]Corporate Ownership and Commercialization
Merle Robbins, the inventor of Uno in 1971, initially produced and sold the game decks himself from his barbershop in Reading, Ohio, with limited local distribution through friends and businesses. In 1972, Robbins sold the rights to the game to Robert Tezak, a funeral parlor owner in Joliet, Illinois, for $50,000 plus royalties of 10 cents per deck sold. Tezak established International Games, Inc., to handle production and marketing, with manufacturing outsourced to Saltzman Printers and initial offices located behind his funeral home. Under International Games, Uno expanded beyond local sales, achieving broader U.S. distribution during the 1970s and 1980s, though exact sales figures from this period remain undocumented in primary records. On January 23, 1992, Mattel Inc. acquired International Games in a stock-swap transaction of undisclosed value, integrating Uno and Skip-Bo into its portfolio as its entry into the card game market. This acquisition marked a pivotal shift in commercialization, leveraging Mattel's global infrastructure for mass production, international licensing, and aggressive marketing. Post-acquisition, Uno's availability expanded to over 80 countries, with Mattel introducing variants, themed editions, and digital adaptations to sustain demand. By 2025, Uno has maintained status as the top-selling card game, recording nine consecutive quarters of sales growth under Mattel's stewardship. Mattel's strategies, including experiential marketing like the 2025 launch of Uno Social Clubs and targeted campaigns during the COVID-19 pandemic—which saw U.S. sales surge 116% year-over-year in May 2020—have driven annual revenue increases exceeding 20% since 2017 in core markets.Core Gameplay Mechanics
Uno is played with a deck of 108 cards, consisting of 76 numbered cards (one 0 and two each of 1 through 9 in four colors: red, blue, green, and yellow) and 32 action and wild cards.[4] The game accommodates 2 to 10 players, with each receiving 7 cards dealt face down; the remaining cards form a face-down draw pile, and the top card of the draw pile is turned face up to start the discard pile.[1] Play proceeds clockwise around the table, beginning with the player to the dealer's left.[11] The objective is to be the first player to discard all cards from one's hand by matching the top card of the discard pile either by color or by number (or symbol for certain cards).[1] On a player's turn, they must play a matching card from their hand onto the discard pile if possible; if unable to match, they draw one card from the draw pile and may play it immediately if it matches, or otherwise end their turn with the drawn card added to their hand.[11] When the draw pile is depleted, the discard pile (excluding the top card) is shuffled to form a new draw pile.[1] A player who reduces their hand to a single card must audibly declare "UNO" before or immediately after playing that penultimate card; failure to do so results in a penalty of drawing two cards if challenged by another player before the next player begins their turn.[11] The first player to empty their hand wins the round and scores points based on the cards remaining in opponents' hands: numbered cards by their face value, most action cards at 20 points each, and wild cards at 50 points each.[1] Multiple rounds are played until one player reaches 500 points, at which point they win the game.[11]Special Cards and Strategic Elements
Uno incorporates several action cards that disrupt opponents and provide strategic advantages beyond standard numerical or color matching. The Skip card forces the subsequent player to forfeit their turn, allowing the issuer to maintain momentum.[12] The Reverse card alters the direction of play clockwise or counterclockwise, which can redirect penalties back toward a leading opponent or disrupt an unfavorable sequence.[12] The Draw Two card obliges the next player to draw two cards from the deck and skip their turn, accumulating penalty cards without an intervening play.[12] Wild cards enable the player to designate any color as the next required match, offering versatility when hand composition lacks direct matches.[13] The more potent Wild Draw Four card permits color selection while compelling the next player to draw four cards and lose their turn; however, opponents may challenge its legality if they hold a playable color-matching card, resulting in the issuer drawing four cards instead if the challenge succeeds.[13] In strategy, action cards like Draw Two and Wild Draw Four are often hoarded until opponents hold few cards, maximizing disruption near game end to prevent victory.[14] Players prioritize discarding high-value numbered cards early to minimize scoring penalties, as remaining cards at round's end award points to the winner based on their face values (e.g., numbered cards score their number, Draw Two or Skip score 20 points each, Wild cards score 50).[15] Wild cards are preserved for critical color shifts, avoiding premature use that might benefit rivals, while Skip and Reverse manipulate turn order to target vulnerable players or evade incoming penalties.[16] Effective play balances offensive disruption with defensive hand management, as over-reliance on actions without numerical progression risks draw pile depletion and hand inflation.[17]Variants, Expansions, and Recent Innovations
Uno features a wide array of variants that modify core mechanics through alternative components or rules, often developed by Mattel to refresh gameplay. Uno Attack, released in 1998, replaces traditional drawing from a deck with a battery-operated launcher that unpredictably dispenses 0 to 12 cards on action triggers, introducing an element of chance and tension via mechanical failure risks in older units.[18] Uno Flip, launched in 2019, employs double-sided cards divided into "light" and "dark" sides; a Flip card switches the active side, inverting action effects—for instance, a light-side Draw Two becomes a dark-side Draw Four equivalent—doubling strategic depth with 112 cards total.[19] These variants maintain shedding objectives but emphasize unpredictability over standard matching.[20] Further variants eliminate traditional constraints entirely, such as Uno All Wild, introduced in 2021, where every card is wild, removing color and number requirements; players declare a color on each play while action cards like Wild Bodyguard protect against targeted penalties, fostering rapid, chaotic turns across 60 cards.[21] Uno Flex, released in 2023, permits matching by color, number, or symbol across flexible card designs, with wild flex cards allowing symbol swaps to adapt plays dynamically.[20] Licensed theme packs, numbering over 100 editions by 2024, apply cosmetic artwork from franchises like Marvel or Disney to standard rules, serving as accessible entry points without mechanical overhaul.[22] Expansions extend base Uno decks with additive cards and rules. The Uno Show 'em No Mercy pack, debuted in 2023, injects 56 cards including Wild Draw +10 and stackable penalties, plus "mercy coins" for players to pay and discard penalty cards, extending games with heightened brutality.[23] Modular add-ons like the Speed Pack append 16 acceleration cards that force immediate plays or chain reactions, compatible with classic sets for customized intensity.[24] Recent innovations prioritize accessibility and novelty. In 2017, Mattel released Uno ColorAdd, incorporating patterns alongside colors for color-blind players, marking an early adaptation for inclusivity without altering fundamentals.[25] By 2022, Uno Wild Twists ventured into collectible playing cards with twisting mechanics, blending Uno's matching with layered effects for extended sessions.[26] As of 2025, physical-digital hybrids like Uno Wonder integrate mobile rule variants with offline card play, while planned core add-on packs promise further modular enhancements.[27] These developments reflect Mattel's strategy to sustain engagement amid market saturation, though critics note some variants dilute original simplicity for commercial novelty.[28]Popularity, Sales, and Cultural Penetration
Uno, the card game, has maintained dominance as the world's top-selling card game since its widespread commercialization in the 1980s, with over 600 editions and variants distributed in more than 80 countries.[29] Estimates indicate that in 2023, a Uno set was sold every second globally, underscoring its sustained commercial appeal despite originating in 1971.[3] Under Mattel's ownership, Uno has driven consistent growth, posting increases for nine consecutive quarters through 2025, even as broader toy sector sales fluctuated.[30] The game's popularity endures across demographics, ranking as the second most popular board game after Monopoly in 2016 and experiencing a resurgence among adults in recent years fueled by nostalgia, strategic depth, and social media-driven rule debates.[31][32] This appeal stems from its simple mechanics accessible to all ages, enabling quick sessions and broad participation, which has sustained relevance over five decades.[3] Culturally, Uno has permeated global entertainment, featuring in films, television shows, literature, and art, while serving as a staple for family and social gatherings that transcend borders.[8] Innovations like the 2017 colorblind-accessible deck have broadened its reach, promoting inclusivity without altering core play.[33] Its digital adaptations and viral online discussions further embed it in contemporary culture, though they occasionally highlight disputes over house rules, reflecting its adaptable yet contentious social dynamic.[34]Criticisms and Debates on Game Design
Critics have frequently argued that Uno's design prioritizes luck over skill, diminishing strategic depth and player agency. The game's reliance on random card draws and unpredictable special card activations often determines outcomes, with skilled play unable to consistently overcome poor hands or fortunate draws by opponents.[35][36] In analyses of card games, Uno is classified as predominantly chance-based, where even optimal decisions—such as timing color changes or holding action cards—yield to the variance of the deck shuffle and draw pile.[37] This imbalance has led reviewers to describe victories as attributable to "sheer, dumb luck" rather than tactical mastery, particularly in longer sessions where repeated draws exacerbate randomness.[38] A central debate revolves around the special cards, especially Draw Two (+2) and Wild Draw Four (+4), which introduce punitive mechanics that can swing games dramatically and foster frustration. Official rules, as clarified by Mattel in 2019 and reiterated in subsequent statements, prohibit stacking these cards—meaning a +2 cannot pass the penalty to the next player by playing another +2 atop it—yet widespread house rules permit stacking, leading to escalating draws (e.g., chains resulting in 12+ cards for one player).[39][40] This discrepancy has sparked ongoing arguments, with Mattel's 2023 X (formerly Twitter) posts affirming non-stacking to maintain game flow, while players contend it reduces bluffing opportunities and strategic hoarding of +4 cards.[39] Critics note that +4 cards, requiring color/number mismatch verification, enable abuse through unrevealed hands, prompting calls for design tweaks to enforce immediate challenges without derailing turns.[41] The vagueness of core rules has also drawn scrutiny, contributing to pervasive house rule variations that undermine consistent design intent. Players often debate whether action cards like Skip or Reverse can chain effects or if ending on a special card (e.g., +4 as the final play) is allowed; Mattel confirmed in 2024 that action cards can conclude the game, resolving one long-standing dispute but highlighting how ambiguous phrasing in rulebooks invites customization.[42] This flexibility, while enhancing replayability for casual groups, is faulted for eroding competitive integrity, as evidenced by frequent player conflicts over interpretations like turn-skipping redundancy or draw pile exhaustion.[41] Reviewers argue the design's simplicity—dealing only seven cards initially and favoring quick turns—exacerbates these issues by limiting mitigation options, turning debates into social friction rather than engaging puzzles.[43] Expansions introducing gimmicky mechanics, such as plastic dispensers in Uno Attack, have been dismissed as superfluous, failing to address core balance flaws like overpowered reverses that randomize participation.[44] Overall, these elements position Uno as accessible for beginners and families but critiqued for lacking depth in sustained play, with calls for revisions emphasizing verifiable challenges and reduced draw penalties to elevate skill.[45] Despite commercial success, the design's chaos—blending strategy with high variance—continues to polarize enthusiasts, who value its social unpredictability against purists decrying insufficient control mechanisms.[46]Other Arts, Entertainment, and Media
Films and Adaptations
In February 2021, Mattel Films announced development of a live-action feature film adaptation of the Uno card game, described as an action heist comedy set in the underground hip-hop scene of Atlanta.[47] The project involves Grammy-nominated rapper Lil Yachty as a producer, with screenwriter Marcy Kelly penning the script.[48] Originally conceived as a heist narrative, the film aimed to expand Mattel's slate of toy-based properties, alongside adaptations like Barbie and Hot Wheels.[49] As of July 2023, the project appeared stalled or shelved, with no confirmed production timeline, casting, or release date despite initial momentum from Mattel's film division.[50] No theatrical or streaming release has occurred by October 2025, distinguishing it from successfully realized Mattel adaptations such as the 2023 Barbie film.[51] A 2016 YouTube video titled Uno: The Movie, a 2-hour-44-minute screen recording of an online Uno match among players, gained viral attention as a comedic parody but does not constitute an official adaptation or narrative film.[52] Fan-generated concepts, such as horror reinterpretations pitched on platforms like Reddit and TikTok, have circulated but remain speculative and unproduced.[53]Music Albums and Songs
¡Uno! is the ninth studio album by the American punk rock band Green Day, released on September 21, 2012, in Australia and September 25, 2012, internationally.[54][55] It comprises 12 tracks and serves as the first installment in the band's ¡Uno! ¡Dos! ¡Tré! trilogy, recorded during an intensive session yielding material for three albums.[56] The album features energetic punk rock songs such as "Nuclear Family" and "Stay the Night," reflecting a return to the band's high-tempo roots amid their transition from major-label pop-punk.[55] It debuted at number two on the Billboard 200 chart, selling 145,000 copies in its first week in the United States.[57] Other albums titled "Uno" include a 1974 progressive rock release by the Italian band UNO, featuring experimental tracks blending rock and classical elements, though it achieved limited commercial success outside niche prog circles.[58] Independently, rapper Orikal Uno issued a self-titled debut album in 2020, produced in collaboration with Anonimust, emphasizing hip-hop beats over three years of development, available primarily through platforms like Bandcamp.[59] Notable songs titled "Uno" include the 2019 single by American rapper Ambjaay, a trap-influenced track with party-themed lyrics referencing counting in Spanish ("Uno, dos, tres"), which gained viral traction on platforms like YouTube, amassing millions of views for its official video.[60][61] Russian rave group Little Big released "Uno" in 2020 as their entry for the Eurovision Song Contest, a Spanglish electronic dance number selected to represent Russia before the event's cancellation due to the COVID-19 pandemic; it charted in several European countries and highlighted the band's satirical style.[62]Television and Other Media
In November 2020, Mattel announced the development of The Uno Game Show, an unscripted television competition series produced in partnership with Propagate Content and Let's Make a Deal showrunner John Quinn, featuring four teams vying to become Uno champions through oversized physical challenges and gameplay elements adapted for broadcast.[63] [64] The format aimed to capture the game's chaotic reversals and strategic draws in a high-stakes arena, but as of October 2025, the series remains unproduced and has not aired on any network.[63] Uno has appeared in nonfiction television programming focused on toy history and innovation. The History Channel's docudrama series The Toys That Built America devoted its Season 3, Episode 6—"Old Games, New Twists"—to the game's commercialization and enduring appeal, airing on November 26, 2023, and highlighting its rivalry with games like Connect Four while emphasizing simple mechanics driving family engagement.[65] The game routinely features in fictional series as a prop for interpersonal dynamics, underscoring its role in casual social settings. Notable examples include an episode of the HBO Max comedy Hacks in 2024, where characters engage in a tense Uno match reflecting generational conflicts, contributing to the game's visibility in contemporary scripted content.[3] Additional cameos span sitcoms and dramas, such as scenes in Fresh Prince of Bel-Air and animated series like The Simpsons, where play illustrates strategy or betrayal without altering core narratives.Organizations and Institutions
Political and Activist Groups
In response to heightened political polarization in the United States during the late 2010s, Mattel released a limited-edition variant called Nonpartisan Uno in November 2019, which eliminates traditional red and blue cards—colors associated with the Democratic and Republican parties, respectively—and introduces a "Veto Politics" card allowing players to skip turns involving political discussion.[66][67] This adaptation, marketed for holiday gatherings, reflects broader cultural efforts to depoliticize family interactions but does not represent an organized activist initiative.[68] Independent parodies of Uno have emerged with explicit political themes, such as the ONE American Card Game, a conservative-oriented version featuring patriotic designs, faith- and freedom-themed cards, and rules parodying traditional Uno mechanics, produced and sold starting around 2023.[69] Similarly, the END THE WOKENESS card game, released in 2024, incorporates red-white-and-blue aesthetics and anti-"woke" humor as a satirical take on cultural debates, though both remain commercial products rather than platforms for formal activism.[70] No dedicated political or activist groups have formed around the Uno card game itself, as evidenced by the absence of organized movements, petitions, or institutional campaigns linking the game to ideological causes beyond these commercial variants. Uno's simple mechanics have occasionally been analogized in discussions of strategy and power dynamics—such as in opinion pieces comparing gameplay to electoral politics—but these remain metaphorical and lack empirical ties to group mobilization.[71][72]Academic and Educational Entities
Educational adaptations of the UNO card game have been incorporated into classroom activities to teach foundational skills such as number recognition, sequencing, color matching, and basic arithmetic operations, with teachers reporting increased student engagement through gamified lessons.[73][74] For example, UNO cards facilitate measurement instruction by generating random numbers for unit conversions, such as kilometers to meters, in interactive board games designed for elementary students.[75] In academic research, customized UNO variants serve as learning media to address specific curricular challenges. A 2022 study developed an UNO-based English card game to aid EFL students in composing descriptive texts, resulting in improved writing outcomes via research and development methodology involving pre- and post-testing.[76] Similarly, a 2024 trial integrated UNO cards with parts-of-speech games to enhance English grammar acquisition, demonstrating measurable gains in student performance through game-based assessment.[77] Further applications include UNO's use in accounting education, where it boosted learning effectiveness as evidenced by higher post-test scores compared to pre-tests in controlled classroom settings.[78] In mathematics pedagogy, a 2025 systematic review analyzed non-digital and digital UNO-type games across educational levels, finding them effective for reinforcing concepts like probability and sequencing, though primarily in informal or supplementary roles rather than core curricula.[79] A separate 2024 study applied UNO to teach ordinal numbers in Arabic language instruction, yielding improved mastery among participants via structured gameplay.[80] No dedicated academic departments or institutions focus exclusively on UNO, but its empirical utility in these peer-reviewed interventions underscores its role as an accessible, low-cost tool for skill-building, with evidence drawn from small-scale efficacy trials rather than large-scale longitudinal studies.[81]Brands and Commercial Enterprises
Uno Pizzeria & Grill is a casual dining restaurant chain originating in Chicago, Illinois, renowned for inventing deep-dish pizza in 1943 when founder Ike Sewell opened the first location at the corner of Ohio and Wabash streets.[82] The brand expanded through franchising, operating over 130 restaurants across the United States and internationally by the 2020s, while also licensing its name for frozen pizza products sold in retail outlets like Walmart under Pizzeria Uno Foods.[83] These products include varieties such as prima pepperoni deep-dish pizza, maintaining the chain's signature thick crust and layered toppings.[84] UNOde50 is a Spanish jewelry brand specializing in handmade, limited-edition pieces crafted from materials like leather, stainless steel, and semi-precious stones, emphasizing bold, unconventional designs without numerical limitations in production runs despite the name.[85] Founded in Madrid, the company focuses on artisanal techniques and has grown into a global brand with retail presence in Europe, the Americas, and Asia, targeting consumers seeking unique accessories like earrings, bracelets, and necklaces.[85] Other commercial entities bearing the Uno name include niche fashion labels, such as a high-end clothing brand launched around 2021 that incorporates classical menswear and womenswear concepts with modern twists, though it remains smaller in scale compared to food and jewelry counterparts.[86] These brands generally operate independently of the card game manufacturer Mattel, which owns the primary Uno trademark for gaming products but licenses experiential extensions like pop-up social clubs.[5]Notable Individuals
People with Surname Uno
Sōsuke Uno (宇野 宗佑, Uno Sōsuke; August 27, 1922 – May 19, 1998) was a Japanese politician who served as the 75th Prime Minister of Japan from June 3 to August 10, 1989, marking the shortest postwar premiership.[87] Born in Moriyama, Shiga Prefecture, to a family operating a sake brewery, he graduated from Kobe University of Commerce and served in the Imperial Japanese Army during World War II.[87] A longtime Liberal Democratic Party member, Uno held roles including foreign minister from 1986 to 1987 before succeeding Noboru Takeshita amid the Recruit scandal's fallout; his resignation followed revelations of payments to a geisha, eroding party support.[88] Shoma Uno (born December 17, 1997) is a Japanese figure skater specializing in men's singles, recognized as a three-time Olympic medalist.[89] He secured a silver medal in the individual event at the 2018 PyeongChang Olympics and contributed to team event medals, including silver at Beijing 2022, while amassing multiple World Figure Skating Championships titles, such as gold in 2022 and 2023.[89] Uno announced his retirement in May 2024 after a career highlighted by technical innovation in quadruple jumps and six Japanese national titles.[90] Caol Uno (宇野 薫, Uno Kaoru; born May 8, 1975), known as "Shoten," is a Japanese mixed martial artist competing primarily at featherweight and lightweight.[91] With a professional record of 34 wins, 23 losses, and 5 draws as of recent bouts, he debuted in Shooto in 1996, later fighting in promotions like Pride FC and UFC, where he earned victories via submission and faced notable opponents including BJ Penn.[92] Uno's career emphasized grappling proficiency, with 17 submission wins.[91] Sandiaga Salahuddin Uno (born June 28, 1969) is an Indonesian businessman, investor, and politician serving as Minister of Tourism and Creative Economy since December 2019.[93] Born in Rumbai, Pekanbaru, Riau, he earned a BBA summa cum laude from Wichita State University in 1990 and an MBA from George Washington University.[93] Previously vice governor of Jakarta from 2017 to 2018 and a 2019 vice presidential candidate, Uno built wealth through coal and investment firms before entering politics with Gerindra Party affiliations.[94]People with Given Name or Mononym Uno
Uno Prii (February 28, 1924 – November 27, 2000) was an Estonian-born Canadian architect who specialized in modernist residential buildings, designing around 250 structures, primarily in Toronto. Immigrating to Canada in 1950 after serving in the Finnish Navy during World War II, Prii graduated cum laude from the University of Toronto's School of Architecture in 1955. His portfolio featured innovative concrete slab towers with distinctive geometric balconies and space-age aesthetics, influencing Toronto's mid-century urban development, including notable projects in the Annex neighborhood and Jane Exbury towers.[95][96] Uno Svenningsson (born July 1, 1959, in Hagelstorp, Sweden) is a Swedish pop singer-songwriter and guitarist active since the late 1970s. He first rose to prominence as the lead vocalist of the pop band Freda's, which disbanded in 1993, before transitioning to a solo career with his self-titled debut album Uno in 1994. Svenningsson's hits include "Under Ytan," and he has maintained a steady output of albums and tours, culminating in a 2024 anniversary tour celebrating 40 years in music.[97][98]Geographical Locations
Places in the United States
Uno refers to several small, unincorporated communities across the United States, primarily rural locales with limited historical documentation beyond geographic records. These settlements, often consisting of scattered residences and lacking formal municipal governance, derive their names from local vernacular or post office designations established in the late 19th or early 20th centuries.[99][100] In Poinsett County, Arkansas, Uno was once a active timber and farming hub in the western region, adjacent to Jackson and Craighead counties, supporting local economies through resource extraction and agriculture before declining into obscurity.[101] The community is situated at approximately latitude 35.649 and longitude -91.028, appearing on the Grubbs U.S. Geological Survey quadrangle map.[99] Kentucky's Uno lies in Hart County, near Horse Cave, at latitude 37.189 and longitude -85.824, marked on the Park USGS map as a populated place with a history tied to informal trade, including local tradition attributing the name to discreet references to moonshine purchases ("you know") by buyers avoiding direct mention.[100][102] In Wyoming County, West Virginia, Uno is a hamlet approximately 7.5 miles west-southwest of Oceana, functioning as a sparsely populated rural outpost without significant commercial or industrial development.[103] Virginia's Uno resides in Madison County, an unincorporated area with minimal infrastructure, documented primarily through geographic surveys and local references as a quiet, low-density settlement.[104]Places Outside the United States
Uno Port, located in Tamano City, Okayama Prefecture, Japan, functions as a primary ferry terminal for routes connecting the mainland of Honshu to Shikoku and various islands in the Seto Inland Sea, such as Naoshima and Shodoshima.[105] The port's development accelerated with the opening of the Uno-Takamatsu ferry line and the Uno Line railway in 1910, establishing it as a key maritime and rail hub for regional transport and trade.[105][106] Today, it supports cruise traffic and serves as an entry point for cultural events like the Setouchi Triennale, with facilities expanded in 2006 to include a 280-meter quay for larger vessels.[105][107] Smaller locales bearing the name Uno exist elsewhere, including one in Hyogo Prefecture, Japan; one in Laguna Province, Philippines; and one in Durango State, Mexico, though these lack the prominence of the Okayama site and primarily denote rural or minor settlements without extensive documented infrastructure or historical significance beyond basic geographic notation.[108]Science and Technology
Computing Hardware and Software
The Arduino Uno is an open-source microcontroller board designed for prototyping interactive electronic projects, education, and hobbyist applications. Introduced in 2010 at Maker Faire New York, it succeeded earlier Arduino models like the Duemilanove and standardized the platform's form factor, pin layout, and branding.[109] The board is based on the ATmega328P 8-bit AVR microcontroller from Microchip Technology, operating at 16 MHz with 32 KB of flash memory (0.5 KB used by the bootloader), 2 KB of SRAM, and 1 KB of EEPROM.[110] It supports input voltages of 7-12 V (recommended) and 6-20 V (limits), with a regulated 5 V output for the microcontroller and 3.3 V pin available.[111] Key hardware features include 14 digital input/output pins (six of which support pulse-width modulation, PWM, on pins 3, 5, 6, 9, 10, and 11), six analog input pins with 10-bit resolution (A0-A5), and a USB interface for programming and serial communication via a type-B connector and ATmega16U2 (or CH340 in some clones) for USB-to-serial conversion.[110] Power can also be supplied via a 2.1 mm barrel jack or directly to the Vin pin. The board measures 68.6 mm by 53.4 mm and includes a reset button, ICSP header for in-circuit serial programming, and a 16 MHz crystal oscillator.[110] Revisions such as Uno Rev3 (introduced around 2011) added dedicated SDA/SCL pins for I2C and improved USB protection, while the 2023 Uno R4 series updated to a 32-bit ARM Cortex-M4 processor for enhanced performance, though the original ATmega328P-based Uno remains widely used for its simplicity and compatibility.[111] Each I/O pin handles up to 40 mA (recommended 20 mA), with a total 3.3 V pin current limit of 50 mA.[110]| Feature | Specification |
|---|---|
| Microcontroller | ATmega328P (8-bit AVR) |
| Clock Speed | 16 MHz |
| Digital I/O Pins | 14 (6 PWM) |
| Analog Inputs | 6 (10-bit ADC) |
| Flash Memory | 32 KB (0.5 KB bootloader) |
| SRAM | 2 KB |
| EEPROM | 1 KB |
| Operating Voltage | 5 V |
| Input Voltage | 7-12 V (recommended) |
pinMode(), digitalWrite(), and analogRead() abstract hardware interactions, supporting rapid prototyping; for example, the setup() and loop() structure defines initialization and repeated execution.[110] Version 1.x of the IDE, released in 2007 and updated through 2024, emphasizes ease for beginners, while version 2.x (from 2022) adds multi-board support, auto-completion, and debugging tools.[112] Third-party tools like PlatformIO integrate with the Arduino framework for advanced users, but the official IDE remains the standard for Uno compatibility.[113]