Sinclair Research Ltd is a British consumer electronics company founded by Clive Sinclair in Cambridge. It was incorporated in 1973 as Westminster Mail Order Ltd, renamed Sinclair Instrument Ltd Science of Cambridge Ltd Sinclair Computers Ltd, Sinclair Research Ltd, it remained dormant until 1976, when it was activated with the intention of continuing Sinclair's commercial work from his earlier company Sinclair Radionics, adopted the name Sinclair Research in 1981. In 1980, Clive Sinclair entered the home computer market with the ZX80 at £99.95, at that time the cheapest personal computer for sale in the United Kingdom. In 1982 the ZX Spectrum was released, becoming the UK's best selling computer, competing aggressively against Commodore and Amstrad. At the height of its success, inspired by the Japanese Fifth Generation Computer program, the company established the "MetaLab" research centre at Milton Hall near Cambridge, in order to pursue artificial intelligence, wafer-scale integration, formal verification and other advanced projects.
A combination of the failures of the Sinclair QL computer and the TV80 led to financial difficulties in 1985, a year Sinclair sold the rights to its computer products and brand name to Amstrad. Sinclair Research Ltd still exists as a one-man company, continuing to market Clive Sinclair's inventions. On 25 July 1961, Clive Sinclair founded Sinclair Radionics Ltd. in Cambridge. The company developed hi-fi products, radios and scientific instruments; when it became clear that Radionics was failing, Sinclair took steps to ensure that he would be able to continue to pursue his commercial goals. In February 1975, he changed the name of Ablesdeal Ltd to Westminster Mail Order Ltd; the name was changed to Sinclair Instrument Ltd in August 1975. Finding it inconvenient to share control after the National Enterprise Board became involved in Radionics in 1976, Sinclair encouraged Chris Curry to leave Radionics, which he had worked for since 1966, get Sinclair Instrument operational; the company's first product was a watch-like Wrist Calculator.
In July 1977, Sinclair Instrument Ltd was renamed Science of Cambridge Ltd. Around the same time, Ian Williamson showed Chris Curry a prototype microcomputer based on a National Semiconductor SC/MP microprocessor and parts from a Sinclair calculator. Curry was encouraged Sinclair to adopt it as a product. In June 1978, Science of Cambridge launched its MK14 microcomputer in kit form. In May 1979, Jim Westwood, Sinclair's chief engineer, designed a new microcomputer based on the Zilog Z80 microprocessor. Sinclair Instrument Ltd introduced the computer as the ZX80 in February 1980, as both a kit and ready-built. In November 1979, Science of Cambridge Ltd was renamed Sinclair Computers Ltd. In March 1981, Sinclair Computers was renamed Sinclair Research Ltd and the Sinclair ZX81 was launched. In February 1982, Timex Corporation obtained a license to manufacture and market Sinclair's computers in the USA under the name Timex Sinclair. In April the ZX Spectrum was launched. In July Timex launched the TS 1000 in the United States.
In March 1982 Sinclair Research Ltd made an £8.55m profit on turnover of £27.17m, including a £383,000 government grant to develop a flat screen. In 1982 Clive Sinclair converted the Barker & Wadsworth mineral water bottling factory at 25 Willis Road, into the company's new headquarters. In January 1983 the ZX Spectrum personal computer was presented at the Las Vegas Consumer Electronics Show. In September the Sinclair TV80 pocket television was launched, but was a commercial failure. In 1983 the company bought Milton Hall in the village of Milton, for £2m, establishing its MetaLab research and development facility there. In late 1983 Timex decided to pull out of the Timex Sinclair venture which, due to strong competition, had failed to break into the United States market. However, Timex computers continued to be produced for several years in other countries. Timex Portugal launched improved versions, the TS 2048 and 2068; the Sinclair QL was announced on 12 January 1984. The QL was nowhere near as successful as Sinclair's earlier computers.
It suffered from several design flaws, Your Sinclair noted that it was "difficult to find a good word for Sinclair Research in the computer press". Working QLs were not available until late summer and complaints against Sinclair regarding delays were upheld by the Advertising Standards Authority in May of that year. Severe were allegations that Sinclair was cashing cheques months before machines were shipped. In the autumn Sinclair was still publicly predicting it would be a "million seller", that 250,000 would be sold by the end of the year. QL production was suspended in February 1985, the price was halved by the end of the year; the ZX Spectrum+, a repackaged ZX Spectrum with a QL-like keyboard, was launched in October 1984 and appeared in WHSmith's shops the day after release. Retailers stocked the machine in large numbers in expectation of good Christmas sales. However, the machine did not sell as well as expected and, because retailers still had unsold stock, Sinclair's income from orders dipped alarmingly in January.
The Spectrum+ had the same technical specifications as the original Spectrum. An enhanced model, the ZX Spectrum 128, was
A parish is a territorial entity in many Christian denominations, constituting a division within a diocese. A parish is under the pastoral care and clerical jurisdiction of a parish priest, who might be assisted by one or more curates, who operates from a parish church. A parish covered the same geographical area as a manor, its association with the parish church remains paramount. By extension the term parish refers not only to the territorial entity but to the people of its community or congregation as well as to church property within it. In England this church property was technically in ownership of the parish priest ex-officio, vested in him on his institution to that parish. First attested in English in the late, 13th century, the word parish comes from the Old French paroisse, in turn from Latin: paroecia, the latinisation of the Ancient Greek: παροικία, translit. Paroikia, "sojourning in a foreign land", itself from πάροικος, "dwelling beside, sojourner", a compound of παρά, "beside, by, near" and οἶκος οἶκος, "house".
As an ancient concept, the term "parish" occurs in the long-established Christian denominations: Catholic, Anglican Communion, the Eastern Orthodox Church, Lutheran churches, in some Methodist, Congregationalist and Presbyterian administrations. The eighth Archbishop of Canterbury Theodore of Tarsus appended the parish structure to the Anglo-Saxon township unit, where it existed, where minsters catered to the surrounding district. Broadly speaking, the parish is the standard unit in episcopal polity of church administration, although parts of a parish may be subdivided as a chapelry, with a chapel of ease or filial church serving as the local place of worship in cases of difficulty to access the main parish church. In the wider picture of ecclesiastical polity, a parish see. Parishes within a diocese may be grouped into a deanery or vicariate forane, overseen by a dean or vicar forane, or in some cases by an archpriest; some churches of the Anglican Communion have deaneries as units of an archdeaconry.
The Church of England geographical structure uses the local parish church as its basic unit. The parish system survived the Reformation with the Anglican Church's secession from Rome remaining untouched, thus it shares its roots with the Catholic Church's system described above. Parishes may extend into different counties or hundreds and many parishes comprised extra outlying portions in addition to its principal district being described as'detached' and intermixed with the lands of other parishes. Church of England parishes nowadays all lie within one of 44 dioceses divided between the provinces of Canterbury, 30 and York, 14; each parish has its own parish priest and supported by one or more curates or deacons - although as a result of ecclesiastical pluralism some parish priests might have held more than one parish living, placing a curate in charge of those where they do not reside. Now, however, it is common for a number of neighbouring parishes to be placed under one benefice in the charge of a priest who conducts services by rotation, with additional services being provided by lay readers or other non-ordained members of the church community.
A chapelry was a subdivision of an ecclesiastical parish in England, parts of Lowland Scotland up to the mid 19th century. It had a similar status to a township but was so named as it had a chapel which acted as a subsidiary place of worship to the main parish church. In England civil parishes and their governing parish councils evolved in the 19th century as ecclesiastical parishes began to be relieved of what became considered to be civic responsibilities, thus their boundaries began to diverge. The word "parish" acquired a secular usage. Since 1895, a parish council elected by public vote or a parish meeting administers a civil parish and is formally recognised as the level of local government below a district council; the traditional structure of the Church of England with the parish as the basic unit has been exported to other countries and churches throughout the Anglican Communion and Commonwealth but does not continue to be administered in the same way. The parish is the basic level of church administration in the Church of Scotland.
Spiritual oversight of each parish church in Scotland is responsibility of the congregation's Kirk Session. Patronage was regulated in 1711 and abolished in 1874, with the result that ministers must be elected by members of the congregation. Many parish churches in Scotland today are "linked" with neighbouring parish churches served by a single minister. Since the abolition of parishes as a unit of civil government in Scotland in 1929, Scottish parishes have purely ecclesiastical significance and the boundaries may be adjusted by the local Presbytery; the church in Wales is made up of six dioceses. Parishes were civil administration areas until communities were established in 1974. Although they are more simply called congregations and have no geographic boundaries, in the United Methodist Church congregations are called parishes. A prominent example of this usage comes in The Book of Discipline of The United Methodist Church, in which the committee of every local congregation that handles staff support is referred to as the committee on Pastor-Parish Relations.
This committee gives recommendations to the bishop on behalf of the parish/congregation since it is the United Methodist Bishop of the episcopal area who appoints a pastor to each congregation. The same is true in the Af
The ZX Microdrive is a magnetic tape data storage system launched in July 1983 by Sinclair Research for its ZX Spectrum home computer. It was proposed as a cheaper alternative to the floppy disk, but it suffered from poor reliability and lower speed; the Microdrive technology was also used in the Sinclair QL and ICL One Per Desk personal computers. The minimum storage capacity of a Microdrive tape cartridge was 85 KB, it is claimed the Microdrive concept was suggested by Andrew Grillet at an interview with Sinclair Research in 1974. Grillet proposed "a version of the Learjet Stereo 8 system, modified to allow two 64k core images per track for roll-out roll-in swapping using the KUTS protocol". Grillet was offered a better-paying job at Xerox Corporation, never worked for Sinclair Research. Development of the ZX Microdrive hardware by Sinclair engineers Jim Westwood, David Southward and Ben Cheese started in 1982. Of Sinclair Research, the ZX Microdrive was comparatively cheap and technologically innovative but rather limited.
Connecting a ZX Microdrive to a ZX Spectrum required the ZX Interface 1 unit, costing £49.95, although this could be bought packaged with a Microdrive for £79.95. In March 1985, the ZX Spectrum Expansion System was launched for £99.95. This consisted of Interface 1, a Microdrive, a blank cartridge and several cartridges containing Tasword Two word processor plus Masterfile filing system, Quicksilva's Games Designer and Ant Attack game, an introductory cartridge. A total of eight ZX Microdrive units could be connected to the Interface 1 by daisy chaining one drive to the next via an electrical connector block. Microdrives used tiny cartridges containing a 5-metre endless loop of magnetic tape, 1.9 mm wide, driven at 76 cm/second. The cartridges held a minimum of 85 kB; the data retrieval rate was i.e. 120 kbit/s. It was possible to "expand" the capacity of a fresh microdrive cartridge by formatting it several times; this caused the tape to stretch increasing the length of the tape loop so that more sectors can be marked out on it.
This procedure was documented in the Sinclair community magazines of the 1980s. The system acquired a reputation for unreliability; the tapes stretched during use rendering the data stored unreadable. The "write protection" was software-based so that a computer crash could erase the data on an entire tape in 8 seconds; the cartridges were expensive. Similar technology was used in other devices, such as the Rotronics Wafadrive, was sometimes known as a "stringy floppy". Microdrives were used as the native storage medium of the Sinclair QL, which incorporated two internal drives; these were similar to the ZX Microdrive, but used a different logical format, allowing each cartridge to hold at least 100 kB. Mechanically the drives were similar however they ran slower, had a take-up acceleration start instead of the instant start of the ZX Spectrum drives, putting less strain on the cartridges; the QL included a Microdrive expansion bus allowing the attachment of up to six external QL Microdrives. These were never produced due to lack of demand.
It was however possible to connect ZX Microdrives to a QL by putting a twist in the cable. In addition to the QL versions, dual internal Microdrives were included in the related ICL One Per Desk system; these drives were re-engineered by ICL for greater reliability, used a format incompatible with both ZX and QL Microdrives. Stringy floppy – similar system for the TRS-80 and others ZX Microdrive information — at Planet Sinclair Sinclair User, April 1985, News section
Amstrad is a British electronics company. As of 2006, Amstrad's main business is manufacturing Sky UK interactive boxes. Amstrad was founded in 1968 by Alan Sugar at the age of 21; the name is a contraction of Alan Michael Sugar Trading. It was first listed on the London Stock Exchange in 1980. During the late 1980s, Amstrad had a substantial share of the PC market in the UK. Amstrad was once a FTSE 100 Index constituent but since 2007 is wholly owned by Sky UK; the company had offices in Kings Road, Essex. Amstrad was founded in 1966 by Alan Sugar at the age of 19, the name of the original company being AMS Trading Limited, derived from its founder's initials. Amstrad entered the market in the field of consumer electronics. During the 1970s they were at the forefront of low-priced hi-fi, TV and car stereo cassette technologies. Lower prices were achieved by injection moulding plastic hi-fi turntable covers, undercutting competitors who used the vacuum forming process. Amstrad expanded to the marketing of low cost, low quality amplifiers and tuners, imported from the Far East and badged with the Amstrad name for the UK market.
Their first electrical product was the Amstrad 8000 amplifier, which Sugar would describe as "the biggest load of rubbish I've seen in my life." In 1980, Amstrad went public trading on the London Stock Exchange, doubled in size each year during the early'80s. Amstrad began marketing its own home computers in an attempt to capture the market from Commodore and Sinclair, with the Amstrad CPC range in 1984; the CPC 464 was launched in the UK, Australia, New Zealand, Germany and Italy. It was followed by the CPC CPC 6128 models. "Plus" variants of the 464 and 6128, launched in 1990, increased their functionality slightly. In 1985, the popular Amstrad PCW range was introduced, which were principally word processors, complete with printer, running the LocoScript word processing program, they were capable of running the CP/M operating system. The Amsoft division of Amstrad was set up to provide in-house software and consumables. On 7 April 1986 Amstrad announced it had bought from Sinclair Research "...the worldwide rights to sell and manufacture all existing and future Sinclair computers and computer products, together with the Sinclair brand name and those intellectual property rights where they relate to computers and computer related products."
Which included the ZX Spectrum, for £5 million. This included Sinclair's unsold stock of Sinclair Spectrums. Amstrad made more than £5 million on selling these surplus machines alone. Amstrad launched two new variants of the Spectrum: the ZX Spectrum +2, based on the ZX Spectrum 128, with a built-in tape drive and, the following year, the ZX Spectrum +3, with a built-in floppy disk drive, taking the 3" disks that many Amstrad machines used. In 1986 Amstrad entered the IBM PC-compatible arena with the PC1512 system. In standard Amstrad livery and priced at £399 it was a success, capturing more than 25% of the European computer market, it was MS-DOS-based, but with the GEM graphics interface, Windows. In 1988 Amstrad attempted to make the first affordable portable personal computer with the PPC512 and 640 models, introduced a year before the Macintosh Portable, they ran MS-DOS on an 8 MHz processor, the built-in screen could emulate the Monochrome Display Adapter or Color Graphics Adapter. Amstrad's final attempts to exploit the Sinclair brand were based on the company's own PCs.
Amstrad's second generation of PCs, the PC2000 series, were launched in 1989. However, due to a problem with the Seagate ST277R hard disk shipped with the PC2386 model, these had to be recalled and fitted with Western Digital controllers. Amstrad successfully sued Seagate, but following bad press over the hard disk problems, Amstrad lost its lead in the European PC market. In the early 1990s, Amstrad began to focus on portable computers rather than desktop computers. In 1990, Amstrad tried to enter the video game console market with the Amstrad GX4000, similar to what Commodore did at the same time with the C64 GS; the console, based on the Amstrad 464 Plus hardware, was a complete commercial failure, because it used outdated technology, most games available for it were straight ports of CPC games that could be purchased for much less in their original format. In 1993, Amstrad was licensed by Sega to produce a system, similar to the Sega TeraDrive, going by the name of the Amstrad Mega PC, to try to regain their image in the gaming market.
The system didn't succeed as well as expected due to its high initial retail price of £599. In that same year, Amstrad released the PenPad, a PDA similar to the Apple Newton, released only weeks before it, it was a commercial failure, had several technical and usability problems. It lacked most features that the Apple Newton included, but had a lower price at $450; as Amstrad began to concentrate less on computers and more in communication, they purchased several telecommunications businesses including Betacom, Dancall Telecom, Viglen Computers and Dataflex Design Communications during the early 1990s. Amstrad has been a major supplier of set top boxes to UK satellite TV provider Sky since its launch in 1989. Amstrad was key to the introduction of Sky, as the company was responsible for finding methods to produce the requisite equipment at an attractive price for the consumer - Alan Sugar famously approached "someone who bashes out dustbin lids", to manufacture satellite dishes cheaply, it was the
Portishead is a coastal town on the Severn Estuary, close to Bristol, but within the unitary authority of North Somerset, which falls within the ceremonial county of Somerset, England. It has a population of around 25,000, with a growth rate in excess of surrounding towns. Portishead has a long history as a fishing port; as a Royal Manor it expanded during the early 19th century around the docks, with supporting transport infrastructure. A power station and chemical works were added in the 20th century, but the dock and industrial facilities have since closed and been redeveloped into a marina and residential areas. Portishead was the telephone control centre used by British Telecom for non-direct dialled calls to maritime vessels, a service known as Portishead Radio; the town's population is expanding, Portishead is now a dormitory town for Bristol and its environs, although a range of service industries has grown up. The headquarters of both Avon and Somerset Constabulary and Avon Fire Brigade are in Portishead.
The name Portishead derives from the "port at the head of the river". It has been called Portshead and Portschute at times in its history and Portesheve in the Domesday Book, was locally known as Posset; the town’s recorded history dates back to Roman times, although there is evidence of prehistoric settlement, including polished flint axe heads. There were Iron Age settlements in the area, of which Cadbury Camp was the largest. Other sites that have been identified include a 1,200 by 600 feet site, successively occupied by the Romans and Danes. There is some evidence that it may have been the western end of the Wansdyke, an early medieval or Roman boundary with a series of defensive linear earthworks extending to the Savernake Forest near Marlborough in Wiltshire. After the Norman conquest the manor was held by the Bishop of Coutances and reverted to the crown, after which William II gave it to a merchant from Bristol known as Harding and to his son Robert Fitzharding who became Lord of Berkeley.
The Berkeley family held it for generations until it passed by marriage to the Cokes of Holkham in Norfolk. In the 14th century it belonged to Everard le Frenshe. In 1621 the Bristol Corporation purchased large portions of land in Portishead and revived the Manor Court; the rights of the corporation over the manor was disputed but they held it until 1836 when they sold it for £8,050. The parish of Portishead was part of the Portbury Hundred; the town was built on the mouth of a small tributary of the Severn Estuary near the mouth of the River Avon. The old pill or jetty provided protection for craft against the Bristol Channel's large tidal range, iron rings can be seen in the high street at which fishing boats used to moor, its position meant Portishead was used to guard the "King Road", as the waters around the headland are called. In 1497 it was the departure point for John Cabot on the Matthew. A fort was built on Battery Point, was used during the English Civil War when the town supported the Royalists, but surrendered to Fairfax in 1645.
Guns were placed at Battery Point during World War II. The King Road was the site of a naval action in 1758 when HMS Antelope captured HMS Belliqueux, one of a French squadron returning from Quebec. A mill was built on Welhay stream but this was replaced by tidal mills. In the 17th century the City of Bristol bought the manors of North Weston and Portishead for access to the channel and as a place to stay outside of the city and, in the 19th century, as a seaside resort. An outer sea wall was built allowing the local marshes to be drained and increased the land available for farming; the dominant architecture is early Victorian, with some buildings maintaining their original features. The expansion in residential property coincided with the construction of the dock and the rail link to Bristol; the Royal Hotel by the pier was built in a Tudor Gothic style in 1830, to provide accommodation and catering for travellers on the steamers from Bristol and Ireland. The Act of Parliament governing the enclosure of Portishead was passed in 1814, stipulated the right to a public wharf, although there is historical evidence of nautical connections dating back to the Patent Rolls of 1331.
Around the 1860s, at the height of the iron and steel era, a pier and a deep-water dock were built by the Bristol & Portishead Pier and Railway to accommodate the large ships that had difficulty in reaching Bristol Harbour. They exported local products overseas. Ships carrying coal were commonplace in Portishead Docks. In the 1880s Portishead Dock was acquired by Bristol Corporation, was subsequently managed as part of the Port of Bristol until its closure; the Portishead power stations were coal-fed power stations built next to the dock. Construction work started on Portishead "A" power station in 1926, it began generating electricity in 1929 for the Bristol Corporation's Electricity Department. In 1937 its original six short chimney stacks were replaced by a 350 ft high stack. A second 350 ft stack was added when the power station was expanded in 1948. Construction of Portishead "B" power station began in 1949; the power stations became part of the nationalised electricity industry after 1949, were operated in turn by the British Electricity Authority, the Central Electricity Authority and the CEGB.
They used some local coal produced in the Somerset coalfield, delivered by train along the Portishead branch of the Great Western Railway. The line had opened on 12 April 1867 as Railway Company; the main supply of coal was imported by boat from N
Engineers, as practitioners of engineering, are professionals who invent, analyze and test machines, systems and materials to fulfill objectives and requirements while considering the limitations imposed by practicality, regulation and cost. The word engineer is derived from the Latin words ingenium; the foundational qualifications of an engineer include a four-year bachelor's degree in an engineering discipline, or in some jurisdictions, a master's degree in an engineering discipline plus four to six years of peer-reviewed professional practice and passage of engineering board examinations. The work of engineers forms the link between scientific discoveries and their subsequent applications to human and business needs and quality of life. In 1961, the Conference of Engineering Societies of Western Europe and the United States of America defined "professional engineer" as follows: A professional engineer is competent by virtue of his/her fundamental education and training to apply the scientific method and outlook to the analysis and solution of engineering problems.
He/she is able to assume personal responsibility for the development and application of engineering science and knowledge, notably in research, construction, superintending, managing and in the education of the engineer. His/her work is predominantly intellectual and varied and not of a routine mental or physical character, it requires the exercise of original thought and judgement and the ability to supervise the technical and administrative work of others. His/her education will have been such as to make him/her capable of and continuously following progress in his/her branch of engineering science by consulting newly published works on a worldwide basis, assimilating such information and applying it independently. He/she is thus placed in a position to make contributions to the development of engineering science or its applications. His/her education and training will have been such that he/she will have acquired a broad and general appreciation of the engineering sciences as well as thorough insight into the special features of his/her own branch.
In due time he/she will be able to give authoritative technical advice and to assume responsibility for the direction of important tasks in his/her branch. Engineers develop new technological solutions. During the engineering design process, the responsibilities of the engineer may include defining problems and narrowing research, analyzing criteria and analyzing solutions, making decisions. Much of an engineer's time is spent on researching, locating and transferring information. Indeed, research suggests engineers spend 56% of their time engaged in various information behaviours, including 14% searching for information. Engineers must weigh different design choices on their merits and choose the solution that best matches the requirements and needs, their crucial and unique task is to identify and interpret the constraints on a design in order to produce a successful result. Engineers apply techniques of engineering analysis in production, or maintenance. Analytical engineers may supervise production in factories and elsewhere, determine the causes of a process failure, test output to maintain quality.
They estimate the time and cost required to complete projects. Supervisory engineers are responsible for entire projects. Engineering analysis involves the application of scientific analytic principles and processes to reveal the properties and state of the system, device or mechanism under study. Engineering analysis proceeds by separating the engineering design into the mechanisms of operation or failure, analyzing or estimating each component of the operation or failure mechanism in isolation, recombining the components, they may analyze risk. Many engineers use computers to produce and analyze designs, to simulate and test how a machine, structure, or system operates, to generate specifications for parts, to monitor the quality of products, to control the efficiency of processes. Most engineers specialize in one or more engineering disciplines. Numerous specialties are recognized by professional societies, each of the major branches of engineering has numerous subdivisions. Civil engineering, for example, includes structural and transportation engineering and materials engineering include ceramic and polymer engineering.
Mechanical engineering cuts across just about every discipline since its core essence is applied physics. Engineers may specialize in one industry, such as motor vehicles, or in one type of technology, such as turbines or semiconductor materials. Several recent studies have investigated. Research suggests that there are several key themes present in engineers' work: technical work, social work, computer-based work and information behaviours. Among other more detailed findings, a recent work sampling study found that engineers spend 62.92% of their time engaged in technical work, 40.37% in social work, 49.66% in computer-based work. Furthermore, there was considerable overlap between these different types of work, with engineers spending 24.96% of their time engaged in technical and social work, 37.97% in technical and non-social, 15.42% in non-technical and social, 21.66% in non-technical and non-social. Engineering is an information-intensive field, with research finding that engineers spend 55
The ZX Spectrum is an 8-bit personal home computer released in the United Kingdom in 1982 by Sinclair Research. Referred to during development as the ZX81 Colour and ZX82, it was launched as the ZX Spectrum by Sinclair to highlight the machine's colour display, compared with the black and white of its predecessor, the ZX81; the Spectrum was released as eight different models, ranging from the entry level with 16 KB RAM released in 1982 to the ZX Spectrum +3 with 128 KB RAM and built in floppy disk drive in 1987. The Spectrum was among the first mainstream-audience home computers in the UK, similar in significance to the Commodore 64 in the US; the introduction of the ZX Spectrum led to a boom in companies producing software and hardware for the machine, the effects of which are still seen. Some credit it as the machine. Licensing deals and clones followed, earned Clive Sinclair a knighthood for "services to British industry"; the Commodore 64, Dragon 32, Oric-1, Oric Atmos, BBC Micro and the Amstrad CPC range were rivals to the Spectrum in the UK market during the early 1980s.
While the machine was discontinued in 1992, new software titles continue to be released – over 40 so far in 2018. The Spectrum is based on a Zilog Z80 A CPU running at 3.5 MHz. The original model has 16 KB of ROM and either 16 KB or 48 KB of RAM. Hardware design was by Richard Altwasser of Sinclair Research, the outward appearance was designed by Sinclair's industrial designer Rick Dickinson. Video output is through an RF modulator and was designed for use with contemporary television sets, for a simple colour graphic display. Text can be displayed using 32 columns × 24 rows of characters from the ZX Spectrum character set or from a set provided within an application, from a palette of 15 shades: seven colours at two levels of brightness each, plus black; the image resolution is 256×192 with the same colour limitations. To conserve memory, colour is stored separate from the pixel bitmap in a low resolution, 32×24 grid overlay, corresponding to the character cells. In practice, this means that all pixels of an 8x8 character block share one foreground colour and one background colour.
Altwasser received a patent for this design. An "attribute" consists of a foreground and a background colour, a brightness level and a flashing "flag" which, when set, causes the two colours to swap at regular intervals; this scheme leads to what was dubbed colour clash or attribute clash, where a desired colour of a specific pixel could not be selected. This became a distinctive feature of the Spectrum, meaning programs games, had to be designed around this limitation. Other machines available around the same time, for example the Amstrad CPC or the Commodore 64, did not suffer from this limitation; the Commodore 64 used colour attributes in a similar way, but a special multicolour mode, hardware sprites and hardware scrolling were used to avoid attribute clash. Sound output is through a beeper on the machine itself, capable of producing one channel with 10 octaves. Software was available that could play two channel sound; the machine includes an expansion bus edge connector and 3.5 mm audio in/out ports for the connection of a cassette recorder for loading and saving programs and data.
The "ear" port has a higher output than the "mic" and is recommended for headphones, with "mic" for attaching to other audio devices as line in. It was manufactured in Scotland, in the now closed Timex factory; the machine's Sinclair BASIC interpreter is stored in ROM and was written by Steve Vickers on contract from Nine Tiles Ltd. The Spectrum's chiclet keyboard is marked with BASIC keywords. For example, pressing "G" when in programming mode would insert the BASIC command GO TO; the BASIC interpreter was developed from that used on the ZX81 and a ZX81 BASIC program can be typed into a Spectrum unmodified, but Spectrum BASIC included many extra features making it easier to use. The ZX Spectrum character set was expanded from that of the ZX81, which did not feature lower-case letters. Spectrum BASIC included extra keywords for the more advanced display and sound, supported multi-statement lines; the cassette interface was much more advanced and loading around five times faster than the ZX81, unlike the ZX81, the Spectrum could maintain the TV display during tape storage and retrieval operations.
As well as being able to save programs, the Spectrum could save the contents of arrays, the contents of the screen memory, the contents of any defined range of memory addresses. Rick Dickinson came up with a number of designs for the "ZX82" project before the final ZX Spectrum design. A number of the keyboard legends changed during the design phase including ARC becoming CIRCLE, FORE becoming INK and BACK becoming PAPER; the Spectrum reused a number of design elements of the ZX81: The ROM code for things such as floating point calculations and expression parsing were similar. The simple keyboard decoding and cassette interfaces were nearly identical; the central ULA integrated circuit was somewhat similar although it implemented the major enhancement over the ZX81: A hardware based television raster generator that indirectly gave the new machine four times as much processing power as the ZX81 due to the Z80 now being released from this video generation task. A bug in the ULA as designed