how many age of empires games are there

Age of Empires is a series of personal computer games originally developed by Ensemble Studios and published by Microsoft Studios. The first title of the series was Age of Empires, released in 1997. Since then, seven titles and three spin-offs have been released. The titles are historical real-time strategy games.

Age of Empires

Age of Empires focused on events in Europe, Africa and Asia, spanning from the Stone Age to the Iron Age; the expansion game explored the formation and expansion of the Roman Empire. The sequel, Age of Empires II: The Age of Kings, was set in the Middle Ages, while its expansion focused partially on the Spanish conquest of Mexico. The subsequent three games of Age of Empires III explored the early modern period, when Europe was colonizing the Americas and several Asian nations were on the decline. The newest installment, Age of Empires Online, takes a different approach as a free-to-play online game utilizing Games for Windows Live. A spin-off game, Age of Mythology, was set in the same period as the original Age of Empires, but focused on mythological elements of Greek, Egyptian, and Norse mythology. At Gamescom 2017, Microsoft announced the fourth installment of the series, Age of Empires IV as well as Definitive Editions for Age of Empires II and Age of Empires III.

The Age of Empires series has been a commercial success, selling over 20 million copies.[1] Critics have credited part of the success of the series to its historical theme and fair play; the artificial intelligence (AI) players fight with fewer advantages than in many of the series' competitors.[2]

The games in the series focus on historical events throughout time. Age of Empires covers the events between the Stone Age and the Classical period, in Europe and Asia. Its expansion, The Rise of Rome, follows the formation and rise of the Roman Empire. The Age of Kings and its Nintendo DS spin-off follow Europe and Asia through the Middle Ages. The Age of Kings' expansion pack, The Conquerors, is set during the same period, but also includes scenarios about the Spanish conquest of Mexico, El Cid, and Attila the Hun. Age of Empires III and its first expansion, The WarChiefs, take place during the European colonization of the Americas. Its second expansion, The Asian Dynasties, follows the rise of Asia in the same period. Age of Empires Online focuses on the Greek and Egyptian civilizations. The series' spin-off, Age of Mythology, and its expansion pack, The Titans, are set during the Bronze Age, but focus on mythology as their themes, rather than history.

Age of Empires, released on October 26, 1997,[3] was the first game in the series, as well as the first major release from Ensemble Studios.[4] It was one of the first history-based real-time strategy games made,[5] utilizing the Genie game engine. GameSpot described it as a mix of Civilization and Warcraft.[6] The game gives players a choice of 12 civilizations to develop from the Stone Age to the Iron Age. The expansion pack, The Rise of Rome, published by Microsoft on October 31, 1998, introduced new features and four new civilizations, including the Romans. Although the two games had contained many software bugs, patches resolved many of the problems.[7][8]

Age of Empires was generally well received, despite some highly negative reviews. GameSpot criticized a confused design, while Computer and Video Games praised the game as strong in single and multiplayer.[9] The Academy of Interactive Arts & Sciences named Age of Empires the 1998 "Computer Strategy Game of the Year."[10] For several years, the game remained high on the sales charts, with over three million units sold by 2000.[11] The Rise of Rome sold one million units in 2000[11] and attained 80% as an aggregate score from GameRankings.[12]

In June 2017, Adam Isgreen, creative director of Microsoft Studios announced Age of Empires: Definitive Edition at the Electronic Entertainment Expo 2017. It will feature overhauled graphics with support for 4K resolution, a remastered soundtrack, and other gameplay improvements, and was planned to be released on October 19, 2017.[13][14] On October 13, it was announced that the release date of the Definitive Edition would be postponed until early 2018.[15]

Age of Empires II: The Age of Kings, released on September 30, 1999, used the Genie game engine, and had gameplay similar to its predecessor.[16] Age of Kings is set in the Middle Ages, from the Dark Ages to the Imperial Age. It allows players to choose one of 13 civilizations, from Europe, Asia, and the Middle East.[17]

On August 24, 2000, Microsoft published the expansion, The Conquerors. It added new units and five new civilizations, including two Mesoamerican civilizations; the Maya and the Aztec.[18] The Age of Kings was a bigger critical success than the first two games, with Game Rankings and Metacritic scores of 92%.[19][20] Microsoft shipped out more than two million copies to retailers, and the game received numerous awards and accolades.[21] Critics agreed that The Conquerors expanded well on The Age of Kings, though issues of unbalanced gameplay were raised.[22] The Age of Kings and The Conquerors won the 2000 and 2001 "Computer Strategy Game of the Year" awards from the Academy of Interactive Arts & Sciences, respectively.[23][24]

In April 2013, Age of Empires II: HD Edition was released on the Steam digital distribution platform for Windows operating systems. The HD Edition includes both the original game and the expansion The Conquerors, as well as updated graphics for high-resolution displays.[25] In November 2013, a second expansion entitled The Forgotten was released by Microsoft exclusively for the HD Edition.[26] A third expansion named The African Kingdoms was released by Microsoft in November 2015, also exclusively for the HD Edition.[27] A fourth expansion entitled Rise of the Rajas was released on 19 December 2016.[28] On August 21, 2017, Microsoft announced Age of Empires II: Definitive Edition.[29]

Age of Empires III, released on October 18, 2005, was built on an improved version of the Age of Mythology game engine with the most significant changes being the updated graphics engine and the inclusion of the Havok physics middleware engine.[30][31] The game is set in the period between 1421 and 1850, and players can choose one of eight European nations. The game introduced a large number of features, such as home cities. Described by Ensemble Studios as "an important support system to your efforts in the New World," home cities helped provide the player with resources, equipment, troops, and upgrades. They could be used across multiple games, and upgraded after each battle; it was compared to a role-playing game character by Ensemble Studios.[32] The first expansion to Age of Empires III, The WarChiefs, was released October 17, 2006. Most gameplay changes in the expansion pack were small, but it introduced three new civilizations, with a focus on Native Americans.[33] Most notable was the introduction of the WarChief unit.[34] The second expansion, The Asian Dynasties, went on sale October 23, 2007. It was a jointly developed product; Big Huge Games helped Ensemble Studios develop the game, with Brian Reynolds joining Bruce Shelley as lead designer.[35] The game expanded the Age of Empires III universe into Asia, and introduced three new civilizations.[36] Reception towards Age of Empires III was mixed; Game Revolution described it as "about as much fun" as a history textbook, while GameZone argued it was "one of the best looking games, much less an RTS game, that is out on the market currently".[37] It sold more than two million copies, and won the GameSpy "real-time strategy game of the year" award.[38][39] The WarChiefs failed to equal the success of its predecessor, with a lower score on both Game Rankings and Metacritic, and The Asian Dynasties' score was lower still with 80%.[40][41][42][43]

Several collectors' editions of Age of Empires III included a hardcover artbook. The last page of the artbook has a pictorial depiction of the series; the Roman numerals below each panel range from I to V, indicating the series would include an Age of Empires IV and Age of Empires V. Ensemble Studios employee Sandy Petersen said that the image "was total speculation on [their] part."[44]

In 2008, Microsoft announced they were closing down Ensemble Studios following the completion of Halo Wars. Some of its employees would form a new team as part of Microsoft Studios.[45] Kevin Unangst, director of Games for Windows, denied it was the end of the Age of Empires series, telling The San Francisco Chronicle "we're very excited about the future potential for Age of Empires".[46] Edge confirmed, in an interview with Microsoft's corporate vice president of interactive entertainment, Shane Kim, that Microsoft continued to own Age of Empires and that they had plans to continue the series.[47] However, Bruce Shelley wrote in his blog that he would not be part of any new studios formed.[48][49]

On August 21, 2017, Microsoft announced Age of Empires III: Definitive Edition.[29]

On August 21, 2017, Microsoft announced Age of Empires IV, developed by Relic Entertainment.[50]

Age of Mythology shared many elements of gameplay with the main series,[51] and was considered a part of the series, despite its different focus.[52][53] The campaign in Age of Mythology tells the story of an Atlantean, Arkantos, and his quest to find why his people are out of favor with Poseidon.[54] Microsoft published the game on October 30, 2002,[55] and its expansion, The Titans, on October 21, 2003.[56] The Titans featured the Atlanteans as a new civilization.[57] Its campaign is shorter than previous expansions, and centers on Kastor, son of Arkantos, who falls for the lies of the titans and frees them from Tartarus.[58] Age of Mythology sold more than one million units in four months.[59] It scored 89% on Game Rankings and Metacritic.[60][61] The Titans failed to equal the sales success of Age of Mythology, although critics rated it highly.[62][63]

Backbone Entertainment developed Age of Empires: The Age of Kings as a turn-based game for the Nintendo DS. Majesco Entertainment published the game on February 14, 2006. It is similar to other turn-based games, such as Advance Wars, but with a gameplay based on its PC counterpart.[64] Age of Empires: The Age of Kings scored 80% on Game Rankings and Metacritic.[65][66] Konami brought a game of the same title to the PlayStation 2 around five years earlier than the DS version, but the game had little promotion, and sold poorly.[67]

On August 16, 2010, Microsoft announced Age of Empires Online, which was a free-to-play Games for Windows Live online game, it developed in collaboration with Robot Entertainment. It featured Free-to-play experiences via Games for Windows LIVE as well as: A persistent online capital city that lives and grows even when you're offline, Cooperative multiplayer quests, trading and a level-based system that lets you progress at your own pace.[68] Premium content could be earned or purchased, such as access to blueprints and special items, as well as more quests and features. In September 2013, it was announced that the game would remain functional until July 1, 2014, after which it would be shut down due to the content being too expensive to maintain.[69]

On April 13, 2014, Age of Empires: World Domination was announced. It was developed by KLab Games for the iOS, Android and Windows Phone.[70] It was released on December 7, 2015,[71] with the service terminated on 30 November 2016.[72]

On August 25, 2014, Age of Empires: Castle Siege was announced. It is a touch-based game developed by Smoking Gun Interactive. It was released on September 17, 2014 for the Windows PC and Windows Phone 8.[73][74]

The development phases of the Age of Empires games were similar in several ways. Due to the games being based on historical events, the team often had to do large amounts of research.[75] However, the research was not in depth, which, according to Age of Empires designer Bruce Shelley, is "a good idea for most entertainment products."[75] Shelley also said that Ensemble Studios took most of the reference material from children's sections at libraries. He pointed out the goal was for the players of the game to have fun, "not [its] designers or researchers."[75] At the Games Convention Developers Conference in 2007, Shelley continued with this thought and explained that the success of the series laid in "making a game which appealed to both the casual and hardcore gamer."[76] Shelley also remarked the Age of Empires games were not about history in itself, but rather "about the human experience;"[76] they focused not simply on what humans had done but on what they could do in the future such as "going into space."[76] Ensemble Studios developed Age of Mythology in a different way than the previous two games. The team had worried they "couldn't get away" with a third historical-based game, and chose mythology as the setting after they had discussed several options.[77]

The artificial intelligence (AI) used in the Age of Empires series has been developed and improved regularly by designers. AI specialist Dave Pottinger noted the development team gave the AI in the original game a very high priority, and spent over a year working on it. He said that the AI in the game relies on tactics and strategies to win, instead of "cheating" by giving bonus resources to itself, or tweaking its units to be stronger than normal.[2] Pottinger later noted that the Age of Empires series team took great pride in their AI playing a "fair game".[78]

Age of Empires allows players to choose to play either along specialized, story-backed conditions or as individual battles against the AI (and other players). Choosing to battle against the AI – rather than following the storyline – allows the AI to adapt to players' strategies and even remember which games it won and lost. The AI eventually overcomes players' strategies and easily destroys their villages after several games. For instance, in Age of Empires III, this is referred to as playing a "Skirmish." However Age of Empires III allows players to refine their strategies further against the AI by "Building a Deck," which allows players to replace "Home City" shipments with improved alternatives.

In Age of Empires II: The Conquerors the AI was given a high priority, the result being the "smart villager" feature, which was included in subsequent games of the series. After building a structure that stores or produces resources, smart villagers would proceed to collect resources related to the structure, such as crops from farms or ore from exposed deposits.[79]

Age of Mythology: The Titans lets players use an AI debugger when creating custom scenarios; players can change the settings of computer players and make them act according to certain patterns.[80] More basic changes to the AI had previously been available in the series' first two games.[81]

The graphics and visuals of Age of Empires improved with each successive release. From the original release to the second, Age of Empires II: The Age of Kings, noteworthy improvements gained praise from several critics.[82][83][84] With the release of Age of Mythology the praise continued,[82][85][86][87] and the fourth release, Age of Empires III, garnered even more.[88][89][90]

GameSpot praised the improved graphics[82] in the second release, Age of Empires II: The Age of Kings. Eurogamer welcomed its introduction of female villagers[91] as compared with the original male only version. Allgame praised the advanced grouping and path-finding systems in the second release.[83] Despite the improved graphics, Allgame complained that units in Age of Empires II: The Age of Kings were at times difficult to distinguish from one another,[83] a point numerous reviewers agreed on.[82][92] Nevertheless, Game Revolution wrote that the second release was "the best looking of the 2D RTS games out there right now."[84]

The graphics continued to improve in Age of Mythology and was praised by a majority of reviewers. IGN ranked the graphics in this third release, "a joy to watch... awesome."[85] GameSpot assented, also rating the graphics a 9 out of 10.[82] Game Revolution agreed,[86] and PC Gamer stated that the graphics in the third release "are packed with detail."[87]

The trend in improved graphics continued well into the next release, Age of Empires III, much to the delight of reviewers. IGN stated, "After seeing the screenshots, our jaws hit the floor at the amount of detail."[88] 1UP.com described Age of Empires III as "one of the most beautiful games you will put on your computer for the foreseeable future."[89] GameSpy agreed, stating, "Age III's graphics are unmatched in the strategy genre."[90] Age of Empires III builds on and introduces new features to the prior release, Age of Mythology, such as the inclusion of the award-winning[93] Havok physics simulation middleware[94] game engine for the Windows version and PhysX for the Mac OS X. The innovative result is that pre-created animations are avoided; instead events are calculated according to the physics engine. Consequently, views of events like building destruction and tree felling are not pre-recorded. GameSpot also admired the graphics in the fourth release but complained about "the awkward unit behavior."[95] Other graphical features of the game include bloom lighting and support for pixel shader 3.0.[96]

GameSpy awarded Age of Empires III the "Best Graphics" award at GameSpy's "Game of the Year 2005."[97]

Stephen Rippy has been the series' music director since the first game. He has had occasional help from his brother, David Rippy, as well as Kevin McMullan.[98] He created the original music in Age of Empires with sounds of instruments from the periods in the game.[99] These sounds came from actual instruments, and their digital samples.[99] The tunes were the result of extensive research on the cultures, styles, and instruments used.[99] Rippy said that sound development on The Age of Kings was easy, since there was knowledge of the instruments used in the Middle Ages. Therefore, they were able to reproduce the tunes for the soundtrack of the game.[100] In Age of Mythology, an orchestral instrumentation was used, instead. According to McMullan, the team also collected large numbers of audio recordings from zoos, and created "a massive sound library of [their] own material."[101] The music of Age of Empires III was similar to The Age of Kings, in which the team used more historical instruments; Rippy noted the team used instruments such as "bagpipes and field drums" to give it a realistic feel.[98]

Ensemble Studios worked together with Big Huge Games to develop The Asian Dynasties, Age of Empires III's second expansion. This was the first joint venture for both teams. The reason for them doing so was compatible schedules: Ensemble Studios was busy with other projects—particularly Halo Wars—while Big Huge Games' real-time strategy team had few projects at that time. Big Huge Games did most of the work, but Ensemble Studios designers Greg Street and Sandy Petersen joined in the brainstorming, and had control over the final product.[102] Both studios had roles in testing the game before its release.[103]

The Age of Empires series has been a commercial success. As of 2008, five of its games have each sold more than one million copies. According to Gamasutra, Age of Empires had sold more than three million copies, and The Rise of Rome sold one million copies as of 2000.[11] Around the same time, Microsoft announced that they shipped over two million copies of The Age of Kings.[21] In 2003, Microsoft announced the sales of one million copies for Age of Mythology.[59] By 2004—prior to the release of Age of Empires III—the Age of Empires franchise had sold over 15 million copies.[116] On May 18, 2007, Ensemble Studios announced that two million copies of Age of Empires III had been sold.[38] Games in the series have consistently scored highly on video game review aggregator websites GameRankings and Metacritic, which collect data from numerous review websites. As noted in the adjacent table, the highest rating game is Age of Empires II: The Age of Kings, receiving a 92% score from both sites.[19][20]

Critics have credited Age of Empires for influencing real-time strategy (RTS) games such as Rise of Nations, Empire Earth, and Cossacks.[117][118] Star Wars: Galactic Battlegrounds was also influenced by the series: it utilized the Genie game engine, as Age of Empires and Age of Empires II: The Age of Kings had, and was considered by critics to be a very close replica to the games; IGN began their review with the statement "I love Age of Star Wars, I mean Star Empires. Whatever it's called, I dig it."[119] and GameSpot wrote that "fundamentals of the Age of Empires II engine are so intact in Star Wars: Galactic Battlegrounds that veterans of that game can jump right in."[120] In October 2005, Shelley commented on the impact of the series. In a GameSpy interview, he explained that parents would "tell Ensemble Studios that their kid is reading books about ancient Greece because they enjoy playing with the triremes so much, or that they want to check out books about medieval history because [the] game taught them what a trebuchet was."[121]

Shelley has said that the key to the success of the games was its innovation, rather than imitation of its peers. He also claimed the unique elements in the games "helped establish the reputation of Ensemble Studios as masters of the real-time strategy genre."[122] Mark Bozon of IGN wrote in his review of The Age of Kings, "The Age of Empires series has been one of the most innovative real-time strategy games for PC in the last decade or so."[123] Gamenikki called Ensemble Studios "the developer that started it all" when they talked about how much Age of Empires III had done to advance the real-time strategy genre.[124] Shelley has acknowledged the success and innovation of Age of Empires helped to ensure Ensemble survive its early periods since startup.[125] In 2005, Shelley complained of critics holding an "innovation bias" against the series; citing the 60% score from Computer Gaming World, he said that despite Age of Empires III being "perhaps the best selling PC game in the world," reviewers expected "something really new," and rated it harshly.[126]

Bungie Studios chose Ensemble Studios to develop Halo Wars, an RTS game based on their Halo series. They said that one of the reasons they chose to work with Ensemble was because of the "awesometastic" Age of Empires series.[127] They also noted that Ensemble was the perfect choice "to realize the original vision of Halo," which started life as an RTS.[127]


who invented the first memory disk or floppy disk why is it named that

IBM Direct Access Storage Product Manager, Alan Shugart, assigned the job to David L. Noble,[8] who tried to develop a new-style tape for the purpose, but without success. The project was reassigned to Donald L. Wartner, 23FD Disk Drive manager, and Herbert E. Thompson, 23FD Disk manager, along with design engineers Warren L. Dalziel, Jay Brent Nilson, and Ralph Flores; and that team developed the IBM 23FD Floppy Disk Drive System (code name Minnow). The disk is a read-only, 8-inch-diameter (200Â mm) flexible diskette called the "memory disk" and holding 80 kilobytes of data. Initially the disk was bare, but dirt became a serious problem so they enclosed it in a plastic envelope lined with fabric that would remove dust particles.[9] The Floppy Disk Patent #3,668,658[10] was issued on June 6, 1972 with named inventors Ralph Flores and Herbert E. Thompson. The Floppy Disk Drive Patent #3,678,481[11] was issued July 18, 1972 with named inventors Warren L. Dalziel, Jay. B. Nilson, and Donald L. Wartner. IBM introduced the diskette commercially in 1971.[12][nb 3]

History of the floppy disk

A floppy disk is a disk storage medium composed of a disk of thin and flexible magnetic storage medium encased in a rectangular plastic carrier. It is read and written using a floppy disk drive (FDD). Floppy disks were an almost universal data format from the late 1970s into the 1990s, used at first as a primary data storage mechanism, and later mostly as a file transfer system as part of what became known as "sneakernet".

Work on a drive that led to the world's first floppy disk and disk drive began in 1967 at a San Jose (CA) IBM facility,[1] and introduced into the market in an 8-inch format in 1972. The more conveniently sized 5¼-inch disks were introduced in 1976, and became almost universal on dedicated word processing systems and personal computers.[2] This format was more slowly replaced by the 3½-inch format, first introduced in 1982. There was a significant period where both were popular.[3] A number of other variant sizes were introduced over time, with limited market success.

Floppy disks remained a popular medium for nearly 40 years, but their use was declining by the mid-1990s.[4][5] The introduction of high speed computer networking and new formats like the USB thumbdrive led to the eventual disappearance of the floppy disk as a standard feature of microcomputers, with a notable point in this conversion being the introduction of the floppy-less iMac in 1998. After 2000, floppy disks were increasingly rare and used primarily with older hardware and especially with legacy industrial computer equipment.

In 1967, IBM tasked their San Jose, California development laboratory to develop a reliable and inexpensive system for loading microcode into their System/370 mainframes in a process called Initial Control Program Load (ICPL).[6] The System/370 was IBM's first computer system family to make extensive usage of volatile read/write semiconductor memory for microcode,[nb 1] so for most models, whenever[nb 2] the power was turned on, the microcode had to be loaded (System/370's predecessor, System/360, generally used non-volatile read-only memory for microcode). IBM also wanted inexpensive media that could be sent out to customers with software updates.[7]

The new device first shipped in 1971 as the 23FD, the program load component of the 2835 Storage Control Unit.[13] and then as a standard part of most System 370 processing units and other IBM products. Internally IBM used another device, code named Mackerel, to write boot disks for distribution to the field.[9]

Alan Shugart left IBM and moved to Memorex where his team shipped the Memorex 650 in 1972, the first commercially available read-write floppy disk drive. The 650 had a data capacity of 175Â kB, with 50 tracks, 8 sectors per track, and 448 bytes per sector. The Memorex disk was "hard-sectored", that is, it contained 8 sector holes (plus one index hole) at the outer diameter (outside data track 00) to synchronize the beginning of each data sector and the beginning of a track.

In 1973, IBM shipped its first read/write floppy disk drive, the 33FD, as a component of the 3740 Data Entry System,[14] code named "IGAR",[9] designed to directly replace IBM's punched card ("keypunch") data entry machines. A significant feature of IBM's read/write disk media was the use of a Teflon-lubricated fabric liner to lengthen media life. In 1976, media supplier Information Terminals Corporation enhanced resilience further by adding a Teflon coating to the magnetic disk itself.[15] The new system used a different recording format that stored up to 250¼ kB on the same disks. Drives supporting this format were offered by a number of manufacturers and soon became common for moving smaller amounts of data. This disk format became known as the Single Sided Single Density or SSSD format. It was designed to hold just as much data as one box of 2000 punch cards.[citation needed] The disk was divided into 77 tracks of 26 sectors (a total of 2002 sectors), each holding 128 bytes.

When the first microcomputers were being developed in the 1970s, the 8-inch floppy found a place on them as one of the few "high speed, mass storage" devices that were even remotely affordable to the target market (individuals and small businesses). The first microcomputer operating system, CP/M, originally shipped on 8-inch disks. However, the drives were still expensive, typically costing more than the computer they were attached to in early days, so most machines of the era used cassette tape instead.

Also in 1973, Shugart founded Shugart Associates which went on to become the dominant manufacturer of 8-inch floppy disk drives. Its SA800 became the industry standard for form factor and interface.

In 1976, IBM introduced the 500 KB Double Sided Single Density (DSSD) format, and in 1977 IBM introduced the 1–1.2 MB Double Sided Double Density (DSDD) format.[16]

Other 8-inch floppy disk formats such as the Burroughs 1Â MB unit failed to achieve any market presence.

In a 1976 meeting, An Wang of Wang Laboratories informed Jim Adkisson and Don Massaro of Shugart Associates that the 8-inch format was simply too large and expensive for the desktop word processing machines he was developing at the time. He argued for a $100 drive.

According to Massaro, Adkisson proposed a smaller size and began working with cardboard mockups before the Wang meeting. George Sollman suggests the size was the average of existing tape drives of the era.[17] It is an urban legend that the physical size came about when they met with Wang at a bar in Boston; when he was asked what size would be appropriate, Wang pointed to a cocktail napkin[18] - there was no such meeting.[17]

The new drive of this size stored 98.5 KB, later increased to 110 KB by adding five tracks.[17][19] The 5¼-inch (133 mm) drive was considerably less expensive than 8-inch drives, and soon started appearing on CP/M machines. At one point, Shugart was producing 4,000 drives a day. By 1978, there were more than 10 manufacturers producing 5¼-inch floppy drives, in competing physical disk formats: hard-sectored (90 KB) and soft-sectored (110 KB). The 5¼-inch formats quickly displaced the 8-inch for most applications, and the 5¼-inch hard-sectored disk format eventually disappeared.

Apple introduced the 5¼-inch Disk II drive for the Apple II in 1978, using GCR encoding to store 35 tracks of 13 sectors of 256 bytes (113 KB). An upgrade to a more sophisticated GCR scheme in 1980 increased track capacity to 16 sectors (140 KB for the disk).

These early drives read only one side of the disk, leading to the popular budget approach of cutting a second write-enable slot and index hole into the carrier envelope and flipping it over (thus, the “flippy disk”) to use the other side for additional storage. This was considered risky by some, for the reason that single sided disks would only be certified by the manufacturer for single sided use. The reasoning was that, when flipped, the disk would spin in the opposite direction inside its cover, so some of the dirt that had been collected by the fabric lining in the previous rotations would be picked up by the disk and dragged past the read/write head.[20][21][22]

Tandon introduced a double-sided drive in 1978, doubling the capacity, and a new “double density” format increased it again, to 360 KB.[nb 4]

For most of the 1970s and 1980s, the floppy drive was the primary storage device for word processors and microcomputers. Since these machines had no hard drive, the OS was usually booted from one floppy disk, which was then removed and replaced by another one containing the application. Some machines using two disk drives (or one dual drive) allowed the user to leave the OS disk in place and simply change the application disks as needed, or to copy data from one floppy to another. In the early 1980s, “quad density” 96-track-per-inch drives appeared, increasing the capacity to 720 KB. RX50[23] was another proprietary format, used by Digital Equipment Corporation's Rainbow-100, DECmate-II, and Pro-350. It held 400 KB[nb 5] on a single side by using 96 tracks per inch and cramming 10 sectors per track.

Floppy disks were supported on IBM's PC DOS and Microsoft's MS-DOS from their beginning on the original IBM PC. With version 1.0 of PC DOS (1981), only single-sided 160 KB floppies were supported. Version 1.1 the next year saw support expand to double-sided 320 KB disks. Finally, in 1983, DOS 2.0 supported 9 sectors per track rather than 8, providing 180 KB on a (formatted) single-sided disk and 360 KB on a double-sided.[24]

In 1984, along with the IBM PC/AT, the high density disk appeared, which used 96 tracks per inch combined with a higher density magnetic media to provide 1,200 KB[nb 6] of storage (formally referred to as 1.2 megabytes). Since the usual (very expensive) hard disk held 10–20 megabytes at the time, this was considered quite spacious. High-density drives could also read and write to double-density disks, allowing an upgrade path. However, there were compatibility problems, in particular with non-HD drives failing to read 360 KB disks written by 1200 KB drives due to their narrower track write head.

Except for labeling, 5¼-inch high-density disks were externally identical to their double-density counterparts. This led to an odd situation wherein the drive itself was unable to determine the density of the disk inserted except by reading the disk media to determine the format. It was therefore possible to use a high-density drive to format a double-density disk to the higher capacity. This usually appeared to work (sometimes reporting a small number of bad sectors)—at least for a time. The problem was that the high-density format was made possible by the creation of a new high-coercivity oxide coating (after soft-sector formatting became standard, previous increases in density were largely enabled by improvements in head technology; up until that point, the media formulation had essentially remained the same since 1976). In order to format or write to this high-coercivity media, the high-density drive switched its heads into a mode using a stronger magnetic field. When these stronger fields were written onto a double-density disk (having lower coercivity media), the strongly magnetized oxide particles would begin to affect the magnetic charge of adjacent particles. The net effect is that the disk would begin to erase itself. On the other hand, the opposite procedure (attempting to format an HD disk as DD) would fail almost every time, as the high-coercivity media would not retain data written by the low-power DD field. High-density 3½-inch disks avoided this problem by the addition of a hole in the disk cartridge so that the drive could determine the appropriate density. However, the coercivity rating between the 3½-inch DD and HD formats, 665 and 720 oersteds, is much narrower than that for the 5¼-inch format, 600 versus 300 oersteds,[25] and consequently it was possible to format a 3½-inch DD disk as HD with no apparent problems.

By the end of the 1980s, the 5¼-inch disks had been superseded by the 3½-inch disks. Though 5¼-inch drives were still available, as were disks, they faded in popularity as the 1990s began. The main community of users was primarily those who still owned 1980s legacy machines (PCs running DOS or home computers) that had no 3½-inch drive; the advent of Windows 95 (not even sold in stores in a 5¼-inch version; a coupon had to be obtained and mailed in) and subsequent phaseout of stand-alone MS-DOS with version 6.22 forced many of them to upgrade their hardware. On most new computers, the 5¼-inch drives were optional equipment. By the mid-1990s, the drives had virtually disappeared as the 3½-inch disk became the predominant floppy disk.

During the development of the Apple Lisa, Apple developed a disk format codenamed Twiggy, and officially known as FileWare. While basically similar to a standard 5¼-inch disk, the Twiggy disk had an additional set of write windows on the top of the disk with the label running down the side. The drive was also present in prototypes of the original Apple Macintosh computer, but was removed in both the Mac and later versions of the Lisa in favor of the 3½-inch floppy disk from Sony. The drives were notoriously unreliable and Apple was criticized for needlessly diverging from industry standards.[26]

Throughout the early 1980s, the limitations of the 5¼-inch format were starting to become clear. Originally designed to be smaller and more practical than the 8-inch format, the 5¼-inch system was itself too large, and as the quality of the recording media grew, the same amount of data could be placed on a smaller surface. Another problem was that the 5¼-inch disks were simply scaled down versions of the 8-inch disks, which had never really been engineered for ease of use. The thin folded-plastic shell allowed the disk to be easily damaged through bending, and allowed dirt to get onto the disk surface through the opening.

A number of solutions were developed, with drives at 2-inch, 2½-inch, 3-inch and 3½-inch (50, 60, 75 and 90 mm), all being offered by various companies. They all shared a number of advantages over the older format, including a small form factor and a rigid case with a slideable write protect catch. The almost-universal use of the 5¼-inch format made it very difficult for any of these new formats to gain any significant market share. Some of these formats included Dysan and Shugart's 3¼-inch floppy disk, the later ubiquitous Sony 3½-inch disk and the 3-inch format:

The 3-inch floppy drive itself was manufactured by Hitachi, Matsushita and Maxell.[30] Only Teac outside this "network" is known to have produced drives. Similarly, only three manufacturers of media (Maxell, Matsushita and Tatung) are known (sometimes also branded Yamaha, Amsoft, Panasonic, Tandy, Godexco and Dixons), but "no-name" disks with questionable quality have been seen in circulation.

Amstrad included a 3-inch single-sided, double-density (180 KB) drive in their CPC and some models of PCW. The PCW 8512 included a double-sided, quad-density (720 KB) drive as the second drive, and later models, such as the PCW 9512, used quad-density even for the first drive. The single-sided double density (180 KB) drive was "inherited" by the ZX Spectrum +3 computer after Amstrad bought the rights from Sinclair. The Oric-1 and Atmos systems from Oric International also used the 3-inch floppy drives, originally shipping with the Atmos, but also supported on the older Oric-1.

Since all 3-inch media were double-sided in nature, single-sided drive owners were able to flip the disk over to use the other side. The sides were termed "A" and "B" and were completely independent, but single-sided drive units could only access the upper side at one time.

The disk format itself had no more capacity than the more popular (and cheaper) 5¼-inch floppies. Each side of a double-density disk held 180 KB for a total of 360 KB per disk, and 720 KB for quad-density disks.[31] Unlike 5¼-inch or 3½-inch disks, the 3-inch disks were designed to be reversible and sported two independent write-protect switches. It was also more reliable thanks to its hard casing.

3-inch drives were also used on a number of exotic and obscure CP/M systems such as the Tatung Einstein and occasionally on MSX systems in some regions. Other computers to have used this format are the more unknown Gavilan Mobile Computer and Matsushita's National Mybrain 3000. The Yamaha MDR-1 also used 3-inch drives.

The main problems with this format were the high price, due to the quite elaborate and complex case mechanisms. However, the tip on the weight was when Sony in 1984 convinced Apple Computer to use the 3½-inch drives in the Macintosh 128K model, effectively making the 3½-inch drive a de-facto standard.

Another 3-inch (75 mm) format was Mitsumi's Quick Disk format. The Quick Disk format is referred to in various size references: 2.8-inch, 3-inch×3-inch and 3-inch×4-inch. Mitsumi offered this as OEM equipment, expecting their VAR customers to customize the packaging for their own particular use; disks thus vary in storage capacity and casing size. The Quick Disk uses a 2.8-inch magnetic media, break-off write-protection tabs (one for each side), and contains a see-through hole near center spindle (used to ensure spindle clamping). Nintendo packaged the 2.8-inch magnetic media in a 3-inch×4-inch housing, while others packaged the same media in a 3 inch×3 inch square housing.

The Quick Disk's most successful use was in Nintendo's Famicom Disk System (FDS). The FDS package of Mitsumi's Quick Disk used a 3-inchÃ—4-inch plastic housing called the "Disk System Card". Most FDS disks did not have cover protection to prevent media contamination, but a later special series of five games did include a protective shutter.[32]

Mitsumi's "3-inch" Quick Disk media were also used in a 3-inchÃ—3-inch housing for many Smith Corona word processors. The Smith Corona disks are confusingly labeled "DataDisk 2.8-inch", presumably referring to the size of the medium inside the hard plastic case.

The Quick Disk was also used in several MIDI keyboards and MIDI samplers of the mid-1980s. A non-inclusive list includes: the Roland S-10[33] and MKS100 samplers, the Korg SQD1, the Korg SQD8[34] MIDI sequencer, Akai's 1985 model MD280 drive for the S-612 MIDI sampler,[35][36][37] Akai's X7000 / S700 (rack version)[38] and X3700,[39] the Roland S-220,[40][41] and the Yamaha MDF1[42] MIDI disk drive (intended for their DX7/21/100/TX7 synthesizers, RX11/21/21L drum machines, and QX1, QX21 and QX5 MIDI sequencers).

As the cost in the 1980s to add 5Â¼-inch drives was still quite high, the Mitsumi Quick Disk was competing as a lower cost alternative packaged in several now obscure 8-bit computer systems. Another non-inclusive list of Quick Disk versions: QDM-01,[43] QDD (Quick Disk Drive) on French Thomson micro-computers, in the Casio QD-7 drive,[44] in a peripheral for the Sharp MZ-700 & MZ-800 system,[45] in the DPQ-280 Quickdisk for the Daewoo/Dynadata MSX1 DPC-200,[46][47] in the Dragon 32/64 machine,[48] in the Crescent Quick Disk 128, 128i and 256 peripherals for the ZX Spectrum,[49] and in the Triton Quick Disk peripheral also for the ZX Spectrum.[49][50]

The World of Spectrum FAQ[51] reveals that the drives did come in different sizes: 128 to 256 kB in Crescent's incarnation, and in the Triton system, with a density of 4410 bits per inch, data transmission rate of 101.6 kbit/s, a 2.8-inch double sided disk type and a capacity of up to 20 sectors per side at 2.5 kB per sector, up to 100 kB per disk. Quick Disk as used in the Famicom Disk System holds 64 kB of data per side, requiring a manual turn-over to access the second side.

Unusually, the Quick Disk utilizes "a continuous linear tracking of the head and thus creates a single spiral track along the disk similar to a record groove."[50] This has led some to compare it more to a "tape-stream" unit than typically what is thought of as a random-access disk drive.[52]

In 1981 Sony introduced their 3½-inch floppy disk cartridge (90.0 mm × 94.0 mm) having a single sided unformatted capacity of 218.8 KB and a formatted capacity of 161.2 KB. A double sided version was available in 1982. This initial Sony design was similar to other less than 5¼-inch designs but somewhat simpler in construction. The first computer to use this format was Sony's SMC 70[53] of 1982. Other than Hewlett-Packard's HP-150 of 1983 and Sony's MSX computers that year, this format suffered from a similar fate as the other new formats; the 5¼-inch format simply had too much market share.

Things changed dramatically in 1982 when the Microfloppy Industry Committee (MIC), a consortium ultimately of 23 media companies, agreed upon a 3½-inch media specification based upon but differing from the original Sony design.[54] The first single-sided drives compatible with this new media specification shipped in early 1983,[55] followed immediately in 1984 by double-sided compatible versions.[56] In 1984, Apple Computer selected the format for their new Macintosh computers.[57] Then, in 1985, Atari adopted it for their new ST line, and Commodore for their new Amiga. By 1988, the 3½-inch was outselling the 5¼-inch.[58] In South Africa, the 3½-inch format was generally called a stiffy disk, to distinguish it from the flexible 5½-inch format.[59][60]

The term "3½-inch" or "3.5-inch" disk is and was rounded from the 90 mm actual dimension of one side of the rectangular cartridge. The actual disk diameter is 85.8 mm (3.38 inch).

The 3½-inch disks had, by way of their rigid case's slide-in-place metal cover, the significant advantage of being much better protected against unintended physical contact with the disk surface than 5¼-inch disks when the disk was handled outside the disk drive. When the disk was inserted, a part inside the drive moved the metal cover aside, giving the drive's read/write heads the necessary access to the magnetic recording surfaces. Adding the slide mechanism resulted in a slight departure from the previous square outline. The irregular, rectangular shape had the additional merit that it made it impossible to insert the disk sideways by mistake as had indeed been possible with earlier formats.

The shutter mechanism was not without its problems, however. On old or roughly treated disks, the shutter could bend away from the disk. This made it vulnerable to being ripped off completely (which does not damage the disk itself but does leave it much more vulnerable to dust), or worse, catching inside a drive and possibly either getting stuck inside or damaging the drive.

Like the 5¼-inch, the 3½-inch disk underwent an evolution of its own. When Apple introduced the Macintosh in 1984, it used single-sided 3½-inch disk drives with an advertised capacity of 400 kB. The encoding technique used by these drives was known as GCR, or Group Coded Recording (similar recording methods were used by Commodore on its 5¼-inch drives and Sirius Systems Technology in its Victor 9000 non-PC-compatible MS-DOS machine). Somewhat later, PC-compatible machines began using single-sided 3½-inch disks with an advertised capacity of 360 kB (the same as a double-sided 5¼-inch disk), and a different, incompatible recording format called MFM (Modified Frequency Modulation). GCR and MFM drives (and their formatted disks) were incompatible, although the physical disks were the same. In 1986, Apple introduced double-sided, 800 kB disks, still using GCR, and soon after, IBM began using 720 kB double-sided double-density MFM disks in PCs like the IBM PC Convertible. IBM PC compatibles adopted it too, while the Amiga used MFM encoding on the same disks to give a capacity of 1 MB (880 KB available once formatted).

An MFM-based, "high-density" format, displayed as "HD" on the disks themselves and typically advertised as "1.44 MB" was introduced in 1987; the most common formatted capacity was 1,474,560 bytes.[nb 7] These HD disks had an extra hole in the case on the opposite side of the write-protect notch. IBM used this format on their PS/2 series introduced in 1987. Apple started using "HD" in 1988, on the Macintosh IIx, and the HD floppy drive soon became universal on virtually all Macintosh and PC hardware. Apple's FDHD (Floppy Disk High Density) drive was capable of reading and writing both GCR and MFM formatted disks, and thus made it relatively easy to exchange files with PC users. Apple later marketed this drive as the SuperDrive. Interestingly, Apple began using the SuperDrive brand name again in 2001 to denote their all-formats CD/DVD reader/writer.[61] Amiga included "HD" floppy drives relatively late, with releasing of Amiga 4000 in 1992, and was able to store 1760 KB on it, with ability in software to read/write PC's 1440 KB/720 KB formats.

Besides Sony, Apple was the first major manufacturer to start selling computers with 3Â½-inch disk drives as well as the first to stop shipping them in 1998 with the introduction of the iMac.

Another advance in the oxide coatings allowed for a new "extra-high density" ("ED") format at 2880 KB introduced on the NeXTcube and NeXTstation in 1991, and on IBM PS/2 model 57 also in 1991, but by the time it was available, it was already too small in capacity to be a useful advance over the HD format and never became widely used. The 3½-inch drives sold more than a decade later still use the same 1.44 MB HD format that was standardized in 1989, in ISO 9529-1,2.


who played mr. carter in welcome back carter

Welcome Back, Kotter is an American sitcom starring Gabe Kaplan as a wisecracking high school teacher in charge of a racially and ethnically diverse remedial class called the "Sweathogs." It marked John Travolta's television debut role. Recorded in front of a live studio audience, it originally aired on ABC from September 9, 1975, to May 17, 1979.[1]

Welcome Back, Kotter

The show stars stand-up comedian and actor Gabriel 'Gabe' Kaplan as the title character, Gabe Kotter, a wisecracking teacher who returns to his alma mater, James Buchanan High School in Brooklyn, New York, to teach a remedial class of loafers, called "Sweathogs." The school's principal is referred to, but rarely seen on-screen. The rigid vice principal, Michael Woodman (John Sylvester White), dismisses the Sweathogs as witless hoodlums, and only expects Kotter to contain them until they drop out or are otherwise banished. As a former remedial student, and a founding member of the original class of Sweathogs, Kotter befriends the current Sweathogs and stimulates their potential. A pupil-teacher rapport is formed, and the students often visit Kotter's Bensonhurst apartment, sometimes via the fire-escape window, much to the chagrin of his wife, Julie (Marcia Strassman).

The fictional James Buchanan High is based on the Brooklyn high school that Kaplan attended in real life, New Utrecht High School,[2] which is also shown in the opening credits. Many of the show's characters were also based on people Kaplan knew during his teen years as a remedial student, several of whom were described in one of Kaplan's stand-up comic routines entitled "Holes and Mellow Rolls." "Vinnie Barbarino" was inspired by Eddie Lecarri and Ray Barbarino; "Freddie 'Boom Boom' Washington" was inspired by Freddie "Furdy" Peyton; "Juan Epstein" was partially inspired by Epstein "The Animal"; however, "Arnold Horshack" was unchanged.

Gabe Kotter is a flippant, but well-meaning teacher who returns to his alma mater, Buchanan High, to teach a group of remedial students known as the Sweathogs. Being a founding member of the original Sweathogs, Kotter has a special understanding of the potential of these supposedly "unteachable" students. On his first day on the job, he launches into a Groucho Marx impersonation. Kotter is married to Julie, with whom he eventually has twin girls, Robin and Rachel. It is confirmed by Julie in the episode "Follow the Leader (part 1)" that Gabe is Jewish. During season four, Kaplan had contract issues with the executive producer, and only appeared in a handful of episodes. In season four, the invisible principal John Lazarus retires, and Kotter becomes the vice-principal. Though he is said to maintain some social studies teaching duties, most of that season's shows are filmed outside his classroom (#11), or if in room 11, Mr. Woodman is teaching. To minimize Kotter's absence, scenes were shot in either the school's hallway, the schoolyard, or the principal's waiting area. Season four ended the series.

Julie Kotter is Gabe's wife and closest friend. Though she has a sense of humor, she often wishes Gabe would take matters more seriously. She is occasionally upset with the amount of time her husband spends with his students, and she is troubled that he allows them to visit their apartment regularly; in the two-part story arc "Follow the Leader", the Sweathogs' constant intrusions lead Julie to separate briefly from Gabe and even seriously consider divorce. Originally from Nebraska, with a college degree in anthropology, Julie eventually became a secretary, and later a substitute teacher at Buchanan after Gabe's promotion to vice-principal. She makes several references to her "world famous tuna casserole", a common meal at the Kotter dinner table, which Gabe and the Sweathogs dislike.

Michael Woodman is the curmudgeonly vice-principal (and later principal) of Buchanan High. He makes no secret of his dislike for the Sweathogs, whom he considers the bottom of the social register at his school. He refers to non-Sweathogs as "real" students. When Kotter was a student at Buchanan, Woodman taught social studies, the same class Kotter returns to Buchanan to teach. His old age, and sometimes his diminutive height, are common jokes with the Sweathogs. Woodman was totally against Kotter's unorthodox teaching methods (though as the series progresses, he begins to tolerate them marginally), and at one point even put Kotter in front of the school's review board in an unsuccessful attempt to have him fired. Nonetheless, in the season one episode "No More Mr. Nice Guy", Woodman is shown to be a gifted teacher, willing to wear historic costumes, and role-play in front of the class during his lessons.

Vinnie Barbarino is a cocky Italian-American, the "unofficial official" leader and resident heartthrob of the Sweathogs. He has a need to be the center of attention, as seen when he admits to making it rain in the school gymnasium. In the two-episode "Follow the Leader," Barbarino quits the Sweathogs and drops out of school in anger when Freddy Washington is chosen as the "leader" of the group, though he returns as leader at the finish of the story. Barbarino's prowess with women is a source of envy (and more often amusement) among his classmates. On occasion, he breaks out in song about his last name sung to the tune of Jan and Deans' song, "Barbara Ann". He was the first of the Sweathogs to move out on his own when he got a job as a hospital orderly. In the first episode of the series and fourth season, he has a girlfriend, Sally. Vinnie is Catholic (often describing his mother as a saint), and, as shown in "I'm Having Their Baby", is a Star Trek fan. Little is known about Vinnie's home life other than that his parents argue a lot ("Follow the Leader (part 2)") and take turns beating him when in a mutual rage. His mother's name is Margie ("The Great Debate"), and he shares a bed with his brother. The episode "Don't Come Up And See Me Sometime" implies that Vinnie is the older of the two. Travolta himself was a high school drop-out.[3]

The class clown of the Sweathogs, Arnold Horshack, is completely comfortable with his oddball, if naÃ¯ve, personality. Horshack was known for his unique observations and his wheezing laugh, similar to that of a hyena. (Palillo revealed on a 1995 episode of The Jenny Jones Show that it originated from the way his father breathed during the last two weeks of his life as he lay dying from lung cancer.) It is possible that academically he is the smartest Sweathog. He is the only central Sweathog character to be promoted out of remedial academics class, but he soon returns after feeling out of place. He has an affection for acting and enjoys old movies, particularly 1930s musicals. He eventually marries Mary Johnson, a co-worker and fellow Sweathog. Although his surname sounds like a term for a bordello, he claimed it is a "very old and respected name" meaning "the cattle are dying." His middle name (and his mother's maiden name) is "Dingfelder."

The hip, black student known as the athletic Sweathog for his skills on the basketball court, Washington claimed his nickname came from his habit of "pretending to play the bass" and singing "Boom-boom-boom-boom!". His trademark phrase is, "Hi, there" (spoken with a deep voice and a broad smile). Though often the voice of reason among his classmates, Washington nonetheless is a willing participant in the Sweathogs' various antics and pranks. Freddie also finds success as a radio disc jockey along with another former Sweathog, Wally "The Wow" (played by George Carlin). At one point, Washington challenges Barbarino for leadership of the Sweathogs, and even replaces him for a time until the group grows tired of his dictatorial style.

Washington has an older sister, who got divorced twice while living in Vermont ("The Longest Weekend"), and a brother, Leroy. In "The Great Debate" it is revealed that he has another brother, Douglas, and that his father's name is Lincoln. Kotter uses his own past to bond with Freddie, because in addition to being a former Sweathog he was also a former star of Buchanan's basketball team.

A fiercely proud Puerto Rican Jew (when asked if his mother was Puerto Rican, Juan replies that his mother's maiden name was Bibbermann and that his grandfather saw Puerto Rico from the ship as he was making his way to America and decided to settle there instead of Miami, making him one of the earliest Puerto Rican Jews; Juan is thus Puerto Rican on his father's side and Jewish on both parents' sides), Epstein is one of the toughest students at Buchanan High, despite his short stature. He normally walks with a tough-man strut, wears a red handkerchief hanging out of his right back pocket, and was voted "Most Likely to Take a Life" by his peers. In the season one episode, "One of Our Sweathogs Is Missing", Epstein was said to be the sixth of ten children (When speaking on the phone to his mother (who had failed to notice that he had been missing for three days), she apparently failed to recognize his name and he had to further identify himself as "Number Six."), although he later mentions, in "I'm Having Their Baby," that his mother only gave birth eight times, implying two of them were twin births. Only four of his siblings are mentioned by name: his brothers Pedro, Irving, and Sanchez ("One of Our Sweathogs Is Missing"), establishing that some of his siblings had Jewish names and others Puerto Rican names, and a younger sister, Carmen ("A Love Story"). Epstein's toughness was downplayed later on, and he became more of a wiseguy. He was also known to have a "buddy" relationship with Principal Lazarus as he often refers to him by his first name, Jack. On a few occasions, when Kotter did his Groucho Marx impersonation, Epstein would jump in and impersonate Chico Marx or Harpo Marx. Epstein's diminutive height, large hair, and fake excuse notes (always signed, "Epstein's Mother"), are common jokes associated with him.

Rosie Totsie is the femme fatale purported to have put the "sweat" in Sweathog, though her reputation is largely exaggerated by the Sweathogs' word of mouth. Her promiscuity is at least in part a reaction to the strict discipline enforced by her father, the Reverend Totsie. To restore her good name, and to prove a point, she fabricates a story about one of the Sweathogs getting her pregnant. The character was a favorite among male viewers but was phased out of the series at the end of the first season when Scott was picked to co-star in the syndicated Norman Lear comedy, Mary Hartman, Mary Hartman.[citation needed] She reprised the role in a 1978 episode, "The Return of Hotsie Totsie", in which it was revealed that she dropped out of school because she became pregnant and had to become a stripper to support her infant child.

A recurring non-Sweathog character in the earlier seasons, Borden is a Straight A student and editor of the Buchanan Bugle, the school newspaper. She was Barbarino's tutor, and even dated him at one point. Despite her academic superiority, she can easily hold her own in a Dozens contest against any Sweathog.

Introduced as a regular character in the fourth and final season, Beau is a handsome, friendly, blond, silver-tongued southerner who transfers from New Orleans after being kicked out of several other schools. He ends up in Kotter's class. The producers sought a heart throb who was not a direct knock-off of the "Italian-Stallion" trend that was permeating Hollywood in the mid-1970s who would improve ratings in the South where the show's New York setting was seen as unrelatable. They wanted to retain female viewers, but avoid a Travolta clone. Beau's first reaction to the term "Sweathog" is, "That sounds gross." He seems to have a way with women, as shown in later episodes. One of his running jokes involves imparting whimsical sayings, such as one about how a real man never steps on a pregnant alligator.

Welcome Back, Kotter's first season was controversial. In Boston, the local ABC affiliate (WCVB-TV) initially refused to air the show.[4] The city was going through a tumultuous school busing program that involved widespread protests and riots, and the local affiliate felt Kotter's fictional integrated classroom would only add fuel to the fire. However, the show became an early ratings success and the affiliate relented, picking it up from its fifth episode.

Teachers in other cities had concerns about how Kotter would be portrayed, so producers allowed a union representative on the set to ensure the show protected the image of those in the profession. Kaplan opposed the idea, at one point asking a reporter if there was a junkman on the set of Sanford and Son to protect the reputation of junkmen.[citation needed]

Censor sentiments of Juvenile delinquency faded after the Sweathogs' antics proved to be silly rather than criminal. Like Kaplan, Hegyes was a fan of the Marx Brothers. Hegyes claimed that he suggested that the Sweathogs be modeled after the Marx Brothers in order to reduce tension.[5]

Ratings slipped greatly in the third season. Kaplan later attributed the decline to the age of the actors playing the Sweathogs, all then in their mid to late twenties, claiming that they were no longer believable as high school students. His idea was to have Kotter join the faculty of a community college attended by the Sweathogs;[6] however, this storyline never materialized. In order to increase viewership, the Kotters had twin girls, but this did not prove to be enough to regain the show's earlier momentum. The show introduced a female Sweathog, Angie Grabowski, played by Melonie Haller.

Major changes took place in the fourth and final season.

Shortly before the season began, the series was moved from its successful Thursday 8:00 pm time slot to Monday 8:00 pm to make way for the impending hit series Mork & Mindy.

Virtually the entire writing staff was fired after season 3, and replaced with veteran writers from family-based series (such as Bob Claver from Leave It To Beaver and The Munsters).

Travolta, who had already starred in box office hits such as Grease, Saturday Night Fever, and Carrie, began to focus more time on his film career. He was featured in eight episodes, earning $2,000 for each one, and he was billed as a special guest star.

Mr. Woodman was promoted to Principal of the school (Principal Lazarus quit to take a "less stressful" job at a high-security prison), and Kotter was promoted to Vice-Principal, purposefully moving the show's focus away from Kotter's class.

Major off-screen disputes led Kaplan to break his contract and reduce his appearances. To help fill the voids, Stephen Shortridge joined the cast as smooth-talking Southerner Beau De LaBarre, and Kotter's wife, Julie, became a school secretary and occasional fill-in teacher, despite having one-year-old twin daughters.

Knowing the series was in a nosedive, producer James Komack attempted to spin-off a newly married Arnold Horshack into a new sitcom (see section below).[citation needed]

The show enjoyed ratings success during its first two seasons, spawning a host of merchandising tie-ins including: lunch boxes, dolls, comic books, novels, and even a board game, advertised as "The 'Up Your Nose With A Rubber Hose' Game" in a commercial with a class full of Sweathog look-alikes featuring Steve Guttenberg as Barbarino. The Sweathogs (or at least an impressionist's version of them) even made a crossover appearance with characters from the Happy Days universe on one track (the disco-themed "Fonzarelli Slide") of a 1976 TV-promoted oldies compilation album.

In 2010, the cast, including: Gabe Kaplan, Marcia Strassman, John Travolta, Robert Hegyes, Lawrence Hilton-Jacobs, and Ellen Travolta were honored at the TV Land Award ceremonies that year. Co-star Ron Palillo was not in attendance.

The popular theme song, "Welcome Back", written and recorded by former Lovin' Spoonful frontman John Sebastian, became a No. 1 hit in the spring of 1976. The show was originally going to be called Kotter, but that was changed because of the theme song lyrics. Sebastian has said he tried to find a more general theme for the song after being unable to find any reasonable rhymes for Kotter.

Sebastian performed the song on Saturday Night Live (April 24, 1976 â€“ Season 1, Episode 18), and memorably flubbed the opening lyrics.

DC Comics published ten issues of a Welcome Back, Kotter comic book starting in 1976.[7] Following its cancellation in 1978, a Limited Collectors' Edition was issued, incorporating a 4-page "On the Set" section and photographs from the show.[8]

A series of novels based on characters and dialog of the series was written by William Johnston and published by Tempo Books in the 1970s.

Mattel produced a series of 9Â inch Welcome Back, Kotter action figures in 1977. Figures produced included Barbarino, Horshack, Epstein, Washington, and Mr. Kotter.[9]

Warner Home Video released a 6-episode Television Favorites collection on February 28, 2006. Due to the success of this release, Warner released the Complete first Season on DVD in Region 1 on June 12, 2007.

On May 7, 2014, it was announced that Shout! Factory had acquired the rights to the series. Ultimately, they released Welcome Back, Kotter: The Complete Series on DVD in Region 1 on August 26, 2014,[10] and have since released the second, third, and fourth seasons as individual sets.[11]

Kotter failed to receive any major awards, though it was nominated for an Emmy Award for Outstanding Comedy Series in 1976 [12] after its first season; it lost to The Mary Tyler Moore Show. The series was also nominated for three technical Emmy Awards: Outstanding Achievement in Videotape Editing for a Series (to Editors Susan Jenkins and Manuel Martinez) in 1976, Outstanding Art Direction for a Comedy Series (to Art Directors Roy Christopher and James Shanahan) in 1978, and Outstanding Individual Achievement â€“ Creative Technical Crafts (to Dick Wilson for sound effects) in 1979.[12]

Several noteworthy performers enjoyed guest stints on Kotter either during or prior to their widespread fame. James Woods guest starred in the first season ("The Great Debate") as Alex Welles, a drama teacher who leads the school debate team ("the Turkeys") in a competition against the Sweathogs. Pat Morita appears in the 1976 episode "Career Day" as Mr. Takahashi. Comedian George Carlin was featured, as was John Astin. Other guest stars included Scott Brady, Ellen Travolta, Richard Moll, Della Reese, and Dinah Manoff who would work with John Travolta again in Grease.

Groucho Marx was set to have a brief walk-on role in one episode. He arrived on-set, but was deemed to be too sick to appear. Pictures of Marx with the cast were taken, but were never released because of his sickly appearance.[13][14]

At least three spin-offs of Kotter were seriously considered, but only one ever became a series. The short-lived Mr. T and Tina starred Pat Morita as Taro Takahashi (Mr. T for short), a brilliant Japanese inventor whom he portrayed in one episode of Kotter. The show was not received well by critics and lasted for five episodes on ABC. There was also talk of developing a spin-off built around the Horshack character and his family, Rich Man, Poor Man; Horshack!, but it never went beyond the backdoor pilot stage, shown as an episode of Kotter. In the mid-1990s, Hegyes announced on The Jenny Jones Show that plans were in the works to create a spin-off featuring the Sweathogs (minus Travolta's Barbarino) all grown up. The project, however, never got off the ground, and little information about it was ever made public.

Kaplan welcomed back Hegyes and Jacobs on his short-lived 1981 sitcom Lewis & Clark. Their characters joked that Kaplan seemed familiar and being a smart guy, "should become a teacher."

The Simpsons referenced the sitcom in the fourth-season episode "Selma's Choice" (episode 9F11), first aired on January 21, 1993. Marge is impressed to find one of the Sweathogs listed as a donor in the Springfield Sperm Bank’s “101 Frozen Pops” catalog. She is disappointed, however, to learn from Selma that it’s not Horshack.[21]

In 1997, Ron Palillo, Robert Hegyes, and Lawrence Hilton-Jacobs reprised their respective roles in a dream sequence in the Mr. Rhodes episode "The Welcome Back Show".

In the mid-2000s, WPIX-TV, Channel 11 in New York City, aired the series in its old Saturday night at 8pm timeslot, pulling surprisingly strong ratings.

In 2012, both Ron Palillo and Robert Hegyes died.[22] Other members of the cast who have died include Marcia Strassman in 2014, John Sylvester White in 1988, and Debralee Scott in 2005.

The show's lunchbox was the subject of the season one finale of the podcast Mystery Show.

In March 2016, the show aired on Me-TV Sunday mornings at 8:00 am and 8:30 am Eastern Time. In September 2017, Antenna TV began airing the show weekdays at 6:30 pm and 1:30 am Eastern.


why are maleic acid and fumaric acid different compounds

Maleic acid or cis-butenedioic acid is an organic compound that is a dicarboxylic acid, a molecule with two carboxyl groups. Its chemical formula is HO2CCH=CHCO2H. Maleic acid is the cis-isomer of butenedioic acid, whereas fumaric acid is the trans-isomer. It is mainly used as a precursor to fumaric acid, and relative to its parent maleic anhydride, maleic acid has few applications.

Maleic acid

Maleic acid is a less stable molecule than fumaric acid. The difference in heat of combustion is 22.7 kJ/mole. The heat of combustion is -1355 kJ/mole.[4] Maleic acid is more soluble in water than fumaric acid. The melting point of maleic acid (135 °C) is also much lower than that of fumaric acid (287 °C). Both properties of maleic acid can be explained on account of the intramolecular hydrogen bonding[5] that takes place in maleic acid at the expense of intermolecular interactions, and that are not possible in fumaric acid for geometric reasons.

In industry, maleic acid is derived by hydrolysis of maleic anhydride, the latter being produced by oxidation of benzene or butane.[6]

Maleic acid is an industrial raw material for the production of glyoxylic acid by ozonolysis.[7]

Maleic acid may be used to form acid addition salts with drugs to make them more stable, such as indacaterol maleate.

Maleic acid is also used as an adhesion promoter for different substrates, such as nylon and zinc coated metals e.g galvanized steel, in methyl methacrylate based adhesives.

The major industrial use of maleic acid is its conversion to fumaric acid. This conversion, an isomerization, is catalysed by a variety of reagents, such as mineral acids and thiourea. Again, the large difference in water solubility makes fumaric acid purification easy.

The isomerization is a popular topic in schools. Maleic acid and fumaric acid do not spontaneously interconvert because rotation around a carbon carbon double bond is not energetically favourable. However, conversion of the cis isomer into the trans isomer is possible by photolysis in the presence of a small amount of bromine.[8] Light converts elemental bromine into a bromine radical, which attacks the alkene in a radical addition reaction to a bromo-alkane radical; and now single bond rotation is possible. The bromine radicals recombine and fumaric acid is formed. In another method (used as a classroom demonstration), maleic acid is transformed into fumaric acid through the process of heating the maleic acid in hydrochloric acid solution. Reversible addition (of H+) leads to free rotation about the central C-C bond and formation of the more stable and less soluble fumaric acid.

Some bacteria produce the enzyme maleate isomerase, which is used by bacteria in nicotinate metabolism. This enzyme catalyses isomerization between fumarate and maleate.

Although not practised commercially, maleic acid can be converted into maleic anhydride by dehydration, to malic acid by hydration, and to succinic acid by hydrogenation (ethanol / palladium on carbon).[9] It reacts with thionyl chloride or phosphorus pentachloride to give the maleic acid chloride (it is not possible to isolate the mono acid chloride). Maleic acid, being electrophilic, participates as a dienophile in many Diels-Alder reactions.

The maleate ion is the ionized form of maleic acid. The maleate ion is useful in biochemistry as an inhibitor of transaminase reactions. Maleic acid esters are also called maleates, for instance dimethyl maleate.

Many drugs that contain amines are provided as the maleate acid salt, e.g. carfenazine, chlorpheniramine, pyrilamine, methylergonovine, and thiethylperazine.


what makes the castle of otranto a gothic novel

The Castle of Otranto is the first supernatural English novel and one of the most influential works of Gothic fiction. It blends elements of realist fiction with the supernatural and fantastical, establishing many of the plot devices and character-types that would become typical of the Gothic: secret passages, clanging trapdoors, pictures begin to move, and doors close by themselves.[3] The poet Thomas Gray told Walpole that the novel made "some of us cry a little, and all in general afraid to go to bed oâ€™nights."[6]

The Castle of Otranto

The Castle of Otranto is a 1764 novel by Horace Walpole. It is generally regarded as the first gothic novel. In the second edition, Walpole applied the word 'Gothic' to the novel in the subtitle â€“ "A Gothic Story".[1] The novel merged medievalism and terror in a style that has endured ever since. The aesthetics of the book shaped modern-day gothic books, films, art, music and the goth subculture.[1]

The novel initiated a literary genre which would become extremely popular in the later 18th and early 19th century, with authors such as Clara Reeve, Ann Radcliffe, William Thomas Beckford, Matthew Lewis, Mary Shelley, Bram Stoker, Edgar Allan Poe, Robert Louis Stevenson and George du Maurier.[2]

The Castle of Otranto was written in 1764 during Horace Walpole's tenure as MP for King's Lynn. Walpole was fascinated with medieval history, building in 1749 a fake gothic castle, Strawberry Hill House.[3]

The initial edition was titled in full The Castle of Otranto, A Story. Translated by William Marshal, Gent. From the Original Italian of Onuphrio Muralto, Canon of the Church of St. Nicholas at Otranto. This first edition purported to be a translation based on a manuscript printed at Naples in 1529[3] and recently rediscovered in the library of "an ancient Catholic family in the north of England". This "ancient Catholic family" is possibly the Percy family, as Walpole would have known the Duke of Northumberland and his wife Elizabeth Percy, though this is not proven. He employed an archaic style of writing to further reinforce this.

The Italian manuscript's story, it was claimed, derived from a story still older, dating back perhaps as far as the Crusades. This Italian manuscript, along with alleged author "Onuphrio Muralto", were Walpole's fictional creations, and "William Marshal" his pseudonym.

In the second and subsequent editions, Walpole acknowledges authorship of his work, writing: "The favourable manner in which this little piece has been received by the public, calls upon the author to explain the grounds on which he composed it" as "an attempt to blend the two kinds of romance, the ancient and the modern. In the former all was imagination and improbability: in the latter, nature is always intended to be, and sometimes has been, copied with success...". There was some debate at the time about the function of literature, that is, whether or not works of fiction should be representative of life, or more purely imaginative (i.e. natural vs. romantic). The first edition was well received by some reviewers who understood the novel as belonging to medieval fiction, "between 1095, the era of the First Crusade, and 1243, the date of the last", as the first preface states; and some referred to Walpole as an "ingenious translator". Following Walpole's admission of authorship, however, many critics were loath to lavish much praise on the work and dismissed it as absurd, fluffy, romantic fiction.

In his 1924 edition of The Castle of Otranto, Montague Summers showed that the life story of Manfred of Sicily inspired some details of the plot. The real medieval castle of Otranto was among Manfred's possessions.[4]

The Castle of Otranto tells the story of Manfred, lord of the castle, and his family. The book begins on the wedding-day of his sickly son Conrad and princess Isabella. Shortly before the wedding, however, Conrad is crushed to death by a gigantic helmet that falls on him from above. This inexplicable event is particularly ominous in light of an ancient prophecy, "that the castle and lordship of Otranto should pass from the present family, whenever the real owner should be grown too large to inhabit it". Manfred, terrified that Conrad's death signals the beginning of the end for his line, resolves to avert destruction by marrying Isabella himself while divorcing his current wife Hippolita, who he feels has failed to bear him a proper heir.

However, as Manfred attempts to marry Isabella, she escapes to a church with the aid of a peasant named Theodore. Manfred orders Theodore's death while talking to the friar Jerome, who ensured Isabella's safety in the church. When Theodore removes his shirt to be killed, Jerome recognizes a marking below his shoulder and identifies Theodore as his own son. Jerome begs for his son's life, but Manfred says Jerome must either give up the princess or his son's life. They are interrupted by a trumpet and the entrance of knights from another kingdom who want to deliver Isabella. This leads the knights and Manfred to race to find Isabella.

Theodore, having been locked in a tower by Manfred, is freed by Manfred's daughter Matilda. He races to the underground church and finds Isabella. He hides her in a cave and blocks it to protect her from Manfred and ends up fighting one of the mysterious knights. Theodore badly wounds the knight, who turns out to be Isabella's father, Frederic. With that, they all go up to the castle to work things out. Frederic falls in love with Matilda and he and Manfred begin to make a deal about marrying each other's daughters. Manfred, suspecting that Isabella is meeting Theodore in a tryst in the church, takes a knife into the church, where Matilda is meeting Theodore. Thinking his own daughter is Isabella, he stabs her. Theodore is then revealed to be the true prince of Otranto and Matilda dies, leaving Manfred to repent. Theodore becomes king and eventually marries Isabella because she is the only one who can understand his true sorrow.

In the preface of the second edition, Walpole creates a heuristic for reading Castle which irrevocably changes the way readers are to view the novel until its end. He claims to blend the new and old styles of romance. The "old" romance is what we would consider pre-novel prose â€“ a main tenet of such writings is their fantastic nature. There is magic, the supernatural abounds and they are wholly unbelievable. The style of the "new" romance is what the novels of the 18th century, when Walpole was writing, would generally have looked like. These novels were realistic: they purported to depict events and people as they truly were.

Walpole then, by attempting to blend these two genres, creates something new â€“ something truly "novel". He creates fantastic situations (helmets falling from the sky, walking portraits, etc.) and places supposedly real people into these situations and allows them to act in a "real" manner. In doing so, he effectively allows fiction to evolve in ways that it would otherwise have not been able to.[citation needed] However, readers then may question to what extent did Walpole succeed in his attempt. Do readers view these characters' reactions as truly realistic, or do they merely seem so because of the heuristic that we are given at the outset of the novel?

Castle introduces many set-pieces that the Gothic novel will become famous for. These include mysterious sounds, doors opening independently of a person, and the fleeing of a beautiful heroine from a licentious male figure.

The first and most obvious connection to William Shakespeare is presented by Horace Walpole himself, in the preface to the second edition of Otranto, in which he "praises Shakespeare as a truly original genius and the exemplar of imaginative liberty, as a part of a defense of Otranto's design".[7] Outside of the preface, Walpole uses several allusions to works by Shakespeare as further emphasis of the connection he wishes to be found between his own work and that of Shakespeare. For example, in Hamlet, "Hamlet's encounter with the Ghost becomes for Walpole a template for terror".[7]

Walpole presents a "more fragmented recasting" of the Ghost in Hamlet, which had served as a representation of the "now unsanctioned, but still popular Catholic view of ghosts as speakers of truth" for Shakespeare.[8] The Catholic elements at play within both Hamlet and Otranto are both invoked to represent a further sense of wonder and mystery to the Protestant audience of both works. The Catholic element was a necessary facet of the "template of terror" that Walpole meant to invoke.

The allusion to Hamlet's experience with the Ghost is meant not only as a "template of terror", but also serves to make the reader invoke the feeling of watching the play itself and he does so on three separate occasions. First, Walpole poses Manfred's encounter with the animated portrait of Ricardo as a connection to the Ghost's initial appearance to Hamlet. Second, when Friar Jerome informs Theodore of the dangers to be found in Otranto and he calls for him to take out his revenge correspond to the Ghost's demand to Hamlet to "remember [him]". Third, Frederic's encounter with the skeletal apparition parallels the final appearance of the Ghost in Hamlet.[7]

The violent question of bloodlines and succession is one that serves as a key element in many of Shakespeare's plays, spanning from Hamlet to Richard II and Macbeth, and it is one that is clearly one of the major concerns of Otranto. The link to Hamlet is strengthened even more because of the matter of incest that is also at play in Otranto. "In Otranto, the castle and its labyrinths become grounds for incest that signal the dissolution of familial bonds",[9] which is also a major point of issue in Hamlet since Hamlet's mother (Gertrude) and his uncle (Claudius) were, in a way, related before their marriage. Both Hamlet and Otranto are literary springboards for discussion on the questions of marriage, as the question of Henry VIII's annulment of his marriage and later marriage to Anne Boleyn were still heated topics of controversy. Henry VIII had both married his brother's wife Catherine of Aragon and later dissolved that marriage due to Catherine's inability to produce a male heir that lived to adulthood. Similarly, Otranto revolves around "a larger sexual contest to secure lineage".[10] Henry VIII dissolved the marriage on grounds that the marriage between Catherine and his older brother, Arthur, had not been consummated. Both Hamlet and Otranto show echoes of this story as major elements within the framework of each literary structure.

The final connection from Otranto to Shakespeare lies in the role that the servants play. Like Shakespeare, Walpole aims to create a "mixture of comedy and tragedy"[8] and one of the ways he does so is by using the minor, servant characters (such as Bianca) as comic relief. This is a trope that Walpole takes from Shakespeare. For example, Shakespeare's mechanicals from A Midsummer Night's Dream also serve as the key comic element.

Jan Švankmajer directed the surrealist short film Castle of Otranto (1979) based on the novel.[11] It took the form of a pseudo-documentary frame story in live action with an abridged adaptation of the story itself presented in cut-out animation in the style of Gothic art.


method of administering a drug by topical friction over skin is called

In other cases, topical is defined as applied to a localized area of the body or to the surface of a body part regardless of the location of the effect.[3][4] By this definition, topical administration also includes transdermal application, where the substance is administered onto the skin but is absorbed into the body to attain systemic distribution. Such medications are generally hydrophobic chemicals, such as steroid hormones. Specific types include transdermal patches have become a popular means of administering some drugs for birth control, hormone replacement therapy, and prevention of motion sickness. One example of an antibiotic that may be applied topically is chloramphenicol.

Topical medication

A topical medication is a medication that is applied to a particular place on or in the body. Most often topical administration means application to body surfaces such as the skin or mucous membranes to treat ailments via a large range of classes including creams, foams, gels, lotions, and ointments.[1] Many topical medications are epicutaneous, meaning that they are applied directly to the skin. Topical medications may also be inhalational, such as asthma medications, or applied to the surface of tissues other than the skin, such as eye drops applied to the conjunctiva, or ear drops placed in the ear, or medications applied to the surface of a tooth. The word topical derives from Greek τοπικός topikos, "of a place".

The definition of the topical route of administration sometimes states that both the application location and the pharmacodynamic effect thereof is local.[2]

If defined strictly as having local effect, the topical route of administration can also include enteral administration of medications that are poorly absorbable by the gastrointestinal tract. One poorly absorbable antibiotic is vancomycin, which is recommended by mouth as a treatment for severe Clostridium difficile colitis.[5]

A medication's potency often is changed with its base. For example, some topical steroids will be classified one or two strengths higher when moving from cream to ointment. As a rule of thumb, an ointment base is more occlusive and will drive the medication into the skin more rapidly than a solution or cream base.[6]

The manufacturer of each topical product has total control over the content of the base of a medication. Although containing the same active ingredients, one manufacturer's cream might be more acidic than the next, which could cause skin irritation or change its absorption rate. For example, a vaginal formulation of miconazole antifungal cream might irritate the skin less than an athlete foot formulation of miconazole cream. These variations can, on occasion, result in different clinical outcomes, even though the active ingredient is the same. No comparative potency labeling exists to ensure equal efficacy between brands of topical steroids (percentage of oil vs water dramatically affect the potency of topical steroid). Studies have confirmed that the potency of some topical steroid products may differ according to manufacturer or brand. An example of this is the case of brand name Valisone cream and Kenalog cream in clinical studies have demonstrated significantly better vasoconstrictions than some forms of this drug produced by generic drug manufacturers.[6] However, in a simple base like an ointment, much less variation between manufacturers is common.

In dermatology, the base of a topical medication is often as important as the medication itself. It is extremely important to receive a medication in the correct base, before applying to the skin. A pharmacist should not substitute an ointment for a cream, or vice versa, as the potency of the medication can change. Some physicians use a thick ointment to replace the waterproof barrier of the inflamed skin in the treatment of eczema, and a cream might not accomplish the same clinical intention

There are many general classes, with no clear dividing line between similar formulations. As a result, what the manufacturer's marketing department chooses to list on the label of a topical medication might be completely different from what the form would normally be called. For example, Eucerin "cream" is more appropriately described as an ointment than as a cream.

Topical solutions can be marketed as rinses, sprays, or drops, and are generally of low viscosity and often use water or alcohol in the base.[7][8][9] The solution can cause drying of the skin if alcohol is used in the base.[10] These are usually a powder dissolved in water, alcohol, and sometimes oil. Alcohol in topical steroids can frequently cause drying if it is used as a base ingredient. There is significant variability between brands. There is a risk of irritation, depending on the preservative(s) and fragrances used in the base. Some examples of topical solutions are given below:

Lotions are similar to solutions but are thicker and tend to be more emollient in nature than solution. They are usually an oil mixed with water, and more often than not have less alcohol than solutions. Lotions can be drying if they contain a high amount of alcohol. There is a significant variability in the ingredients between different lotions.

A mixture that separates into two or three parts with time. Frequently an oil mixed with a water-based solution needs to be shaken into suspension before use. "Shake well before use".

A cream is an emulsion of oil and water in approximately equal proportions. It penetrates the stratum corneum outer layer of skin wall. Cream is thicker than lotion, and maintains its shape when removed from its container. It tends to be moderate in moisturizing tendency. For topical steroid products, oil-in-water emulsions are common. Creams have a significant risk of causing immunological sensitization due to preservatives. It has a high rate of acceptance by patients. There is a great variation in ingredients, composition, pH, and tolerance among generic brands.[11]

An ointment is a homogeneous, viscous, semi-solid preparation, most commonly a greasy, thick oil (oil 80% - water 20%) with a high viscosity, that is intended for external application to the skin or mucous membranes. Ointments have a water number that defines the maximum amount of water that it can contain.They are used as emollients or for the application of active ingredients to the skin for protective, therapeutic, or prophylactic purposes and where a degree of occlusion is desired.

Ointments are used topically on a variety of body surfaces. These include the skin and the mucous membranes of the eye (an eye ointment), chest, vulva, anus, and nose. An ointment may or may not be medicated.

Ointments are usually very moisturizing, and good for dry skin. They have a low risk of sensitization due to having few ingredients beyond the base oil or fat, and low irritation risk. There is typically little variability between brands of drugs. They are often disliked by patients due to greasiness.[11]

The vehicle of an ointment is known as the ointment base. The choice of a base depends upon the clinical indication for the ointment. The different types of ointment bases are:

The medicaments are dispersed in the base and are divided after penetrating the living cells of the skin.

The water number of an ointment is the maximum quantity of water that 100g of a base can contain at 20 °C.

Ointments are formulated using hydrophobic, hydrophilic, or water-emulsifying bases to provide preparations that are immiscible, miscible, or emulsifiable with skin secretions. They can also be derived from hydrocarbon (fatty), absorption, water-removable, or water-soluble bases.

Evaluation of ointments

Properties which affect choice of an ointment base are:

Methods of preparation of ointments

Trituration: In this finely subdivided insoluble medicaments are evenly distributed by grinding with a small amount of the base followed by dilution with gradually increasing amounts of the base.

Fusion: In this method the ingredients are melted together in descending order of their melting points and stirred to ensure homogeneity.

Gels are thicker than liquids. Gels are often a semisolid emulsion sometimes using alcohol as a solvent for the active ingredient. Some gels liquefy at body temperature. Gel tends to be cellulose cut with alcohol or acetone. Gels tend to be self-drying. Gels tend to have greatly variable ingredients between brands. Gels carry a significant risk of inducing hypersensitivity due to fragrances and preservatives. Gel is useful for hairy areas and body folds. In applying gel one should avoid fissures in the skin, due to the stinging effect of the alcohol base. Gel enjoys a high rate of acceptance due to its cosmetic elegance.[11]

Foam can be seen with topical steroid marketed for the scalp.

Transdermal patches can be a very precise time released method of delivering a drug. Cutting a patch in half might affect the dose delivered. The release of the active component from a transdermal delivery system (patch) may be controlled by diffusion through the adhesive which covers the whole patch, by diffusion through a membrane which may only have adhesive on the patch rim or drug release may be controlled by release from a polymer matrix. Cutting a patch might cause rapid dehydration of the base of the medicine and affect the rate of diffusion.

Powder[12] is either the pure drug by itself (talcum powder), or is made of the drug mixed in a carrier such as corn starch or corn cob powder (Zeosorb AF - miconazole powder). Can be used as an inhaled topical (cocaine powder used in nasal surgery).

Medication may be placed in a solid form. Examples are deodorant, antiperspirants, astringents, and hemostatic agents. Some solids melt when they reach body temperature (e.g. rectal suppositories).

Certain contraceptive methods rely on sponge as a carrier of a liquid medicine. Lemon juice embedded in a sponge has been used as a primitive contraception in some cultures.

Cordran tape is an example of a topical steroid applied under occlusion by tape. This greatly increases the potency and absorption of the topical steroid and is used to treat inflammatory skin diseases.

Some medications are applied as an ointment or gel, and reach the mucous membrane via vaporization. Examples are nasal topical decongestants and smelling salt.

Paste combines three agents - oil, water, and powder. It is an ointment in which a powder is suspended.

A tincture is a skin preparation that has a high percentage of alcohol. It would normally be used as a drug vehicle if drying of the area is desired.