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ZX-80
The Sinclair ZX80 is a home computer launched on 29 January 1980 by Science of Cambridge Ltd. (later to be better known as Sinclair Research). It is notable for being one of the first computers available in the United Kingdom for less than a hundred pounds. It was available in kit form for £79.95, where purchasers had to assemble and solder it together, and as a ready-built version at £99.95. The ZX80 was advertised as the first personal computer for under £100 and received praise for its value and documentation. However, it faced criticism for screen blanking during program execution, small RAM size, and the keyboard design. It was very popular straight away, and for some time there was a waiting list of several months for either version of the machine. Name The ZX80 was named after the Z80 processor with the 'X' meaning "the mystery ingredient". Hardware Internally, the machine was designed by Jim Westwood around a Z80 central processing unit with a clock speed of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Home Computer
Home computers were a class of microcomputers that entered the market in 1977 and became common during the 1980s. They were marketed to consumers as affordable and accessible computers that, for the first time, were intended for the use of a single, non-technical user. These computers were a distinct market segment that typically cost much less than business, scientific, or engineering-oriented computers of the time, such as those running CP/M or the IBM PC, and were generally less powerful in terms of computer memory, memory and expandability. However, a home computer often had better video display controller, graphics and sound than contemporary business computers. Their most common uses were word processing, playing video games, and computer programming, programming. Home computers were usually sold already manufactured in stylish metal or plastic enclosures. However, some home computers also came as commercial electronic kits, like the ZX80, Sinclair ZX80, which were both h ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Central Processing Unit
A central processing unit (CPU), also called a central processor, main processor, or just processor, is the primary Processor (computing), processor in a given computer. Its electronic circuitry executes Instruction (computing), instructions of a computer program, such as arithmetic, logic, controlling, and input/output (I/O) operations. This role contrasts with that of external components, such as main memory and I/O circuitry, and specialized coprocessors such as graphics processing units (GPUs). The form, CPU design, design, and implementation of CPUs have changed over time, but their fundamental operation remains almost unchanged. Principal components of a CPU include the arithmetic–logic unit (ALU) that performs arithmetic operation, arithmetic and Bitwise operation, logic operations, processor registers that supply operands to the ALU and store the results of ALU operations, and a control unit that orchestrates the #Fetch, fetching (from memory), #Decode, decoding and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Television
Television (TV) is a telecommunication medium for transmitting moving images and sound. Additionally, the term can refer to a physical television set rather than the medium of transmission. Television is a mass medium for advertising, entertainment, news, and sports. The medium is capable of more than "radio broadcasting", which refers to an audio signal sent to radio receivers. Television became available in crude experimental forms in the 1920s, but only after several years of further development was the new technology marketed to consumers. After World War II, an improved form of black-and-white television broadcasting became popular in the United Kingdom and the United States, and television sets became commonplace in homes, businesses, and institutions. During the 1950s, television was the primary medium for influencing public opinion.Diggs-Brown, Barbara (2011''Strategic Public Relations: Audience Focused Practice''p. 48 In the mid-1960s, color broadcasting was ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
RF Connector
An RF connector (radio frequency connector) is an electrical connector designed to work at radio frequencies in the multi-megahertz range. RF connectors are typically used with coaxial cables and are designed to maintain the shielding that the coaxial design offers. Better models also minimize the change in transmission line impedance at the connection in order to reduce signal reflection and power loss. As the frequency increases, transmission line effects become more important, with small impedance variations from connectors causing the signal to reflect rather than pass through. An RF connector must not allow external signals into the circuit through electromagnetic interference and capacitive pickup. Mechanically, RF connectors may provide a fastening mechanism ( thread, bayonet, braces, blind mate) and springs for a low ohmic electric contact while sparing the gold surface, thus allowing very high mating cycles and reducing the insertion force. Research activity in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Radio Frequency
Radio frequency (RF) is the oscillation rate of an alternating electric current or voltage or of a magnetic, electric or electromagnetic field or mechanical system in the frequency range from around to around . This is roughly between the upper limit of audio frequencies that humans can hear (though these are not electromagnetic) and the lower limit of infrared frequencies, and also encompasses the microwave range. These are the frequencies at which energy from an oscillating current can radiate off a conductor into space as radio waves, so they are used in radio technology, among other uses. Different sources specify different upper and lower bounds for the frequency range. Electric current Electric currents that oscillate at radio frequencies (RF currents) have special properties not shared by direct current or lower audio frequency alternating current, such as the 50 or 60 Hz current used in electrical power distribution. * Energy from RF currents in conduct ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
SECAM
SECAM, also written SÉCAM (, ''Séquentiel de couleur à mémoire'', French for ''sequential colour memory''), is an analog color television system that was used in France, Russia and some other countries or territories of Europe and Africa. It was one of three major analog color television standards, the others being PAL and NTSC. Like PAL, a SECAM picture is also made up of 625 interlaced lines and is displayed at a rate of 25 frames per second (except SECAM-M). However, due to the way SECAM processes color information, it is not compatible with the PAL video format standard. SECAM video is composite video; the luminance (luma, monochrome image) and chrominance (chroma, color applied to the monochrome image) are transmitted together as one signal. All the countries using SECAM have either converted to DVB, Digital Video Broadcasting (DVB), the new pan-European standard for digital television, or are currently in the Digital television transition, process of conversion. S ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
ZX80 Character Set
The ZX80 character set is the character encoding used by the Sinclair Research ZX80 microcomputer with its original 4K Sinclair BASIC, BASIC Read-Only Memory, ROM. The encoding uses one byte per character for 256 code points. It has no relationship with previously established ones like ASCII or EBCDIC, but it is related though not identical to the ZX81 character set, character set of the successor ZX81. Printable characters The character set has 64 unique glyphs present at code points 0–63. With the most significant bit set the character is generated in Reverse video, inverse video; corresponding to code points 128–191. These 128 values are the only displayable ones allowed in the video memory (known as the display file). The remaining code points (64–127 and 192–255) are used as control characters or Sinclair BASIC keywords, while some are unused. The small effective range of only 64 unique glyphs precludes support for Latin alphabet, Latin Letter case, lower case lette ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Personal Computer World
''Personal Computer World'' (''PCW'') (February 1978 - June 2009) was the first British computer magazine. Although for at least the last decade it contained a high proportion of Windows PC content (reflecting the state of the IT field), the magazine's title was not intended as a specific reference to this. At its inception in 1978 'personal computer' was still a generic term (the Apple II, Commodore PET, PET 2001 and TRS-80 had been launched as personal computers in 1977.) The magazine came out before the Wintel (or IBM PC compatible) platform existed; the original IBM PC itself was introduced in 1981. Similarly, the magazine was unrelated to the Amstrad PCW. History ''PCW'' was founded by the Croatian-born Angelo Zgorelec"About the authors" visit-croatia.co.uk. Article retrieved 2006-11-24. in 1978, [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Membrane Keyboard
A membrane keyboard is a computer keyboard whose keys are not separate, moving parts, as with the majority of other keyboards, but rather are pressure pads that have only outlines and symbols printed on a flat, flexible surface. Very little tactile feedback is felt when using such a keyboard. History Membrane keyboards work by electrical contact between the keyboard surface and the underlying circuits when keytop areas are pressed. These models were used with some early 1980s home computers which lead to greater adoption of the design. The keyboards are inexpensive to produce, and are more resistant against dirt and liquids than some other keyboard types. However, due to a low or non-existent tactile feedback, some people have reported difficulty typing with them, especially when larger numbers of characters are being typed. Chiclet keyboards are a variation of the design. Usage Aside from early hobbyist/kit/home computers and some video game consoles, membrane-based QWERTY ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Firmware
In computing Computing is any goal-oriented activity requiring, benefiting from, or creating computer, computing machinery. It includes the study and experimentation of algorithmic processes, and the development of both computer hardware, hardware and softw ..., firmware is software that provides low-level control of computing device Computer hardware, hardware. For a relatively simple device, firmware may perform all control, monitoring and data manipulation functionality. For a more complex device, firmware may provide relatively low-level control as well as hardware abstraction Service (systems architecture), services to higher-level software such as an operating system. Firmware is found in a wide range of computing devices including personal computers, smartphones, home appliances, vehicles, computer peripherals and in many of the integrated circuits inside each of these larger systems. Firmware is stored in non-volatile memory either read-only memory (ROM) or progra ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Read-only Memory
Read-only memory (ROM) is a type of non-volatile memory used in computers and other electronic devices. Data stored in ROM cannot be electronically modified after the manufacture of the memory device. Read-only memory is useful for storing software that is rarely changed during the life of the system, also known as firmware. Software applications, such as video games, for programmable devices can be distributed as ROM cartridge, plug-in cartridges containing ROM. Strictly speaking, ''read-only memory'' refers to hard-wired memory, such as diode matrix or a #Solid-state ROM, mask ROM integrated circuit (IC), that cannot be electronically changed after manufacture. Although discrete circuits can be altered in principle, through the addition of Jump wire, bodge wires and the removal or replacement of components, ICs cannot. Correction of errors, or updates to the software, require new devices to be manufactured and to replace the installed device. Floating-gate ROM semiconductor ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
