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Sinclair BASIC
Sinclair BASIC is a dialect of the programming language BASIC used in the 8-bit home computers from Sinclair Research and Timex Sinclair. The Sinclair BASIC interpreter was made by Nine Tiles Networks Ltd. History Sinclair BASIC was originally developed in 1979 for the ZX80 by Nine Tiles. The programmers were John Grant, the owner of Nine Tiles, and Steve Vickers. It was initially an incomplete implementation of the 1978 American National Standards Institute (ANSI) minimal BASIC standard with integer arithmetic only, termed the 4K BASIC (for its ROM size) for the ZX80. It evolved through the floating-point 8K BASIC for the ZX81 and TS1000 (which was also available as an upgrade for the ZX80), and became an almost complete version in the 16 KB ROM ZX Spectrum (known as 48K BASIC). It is present in all ZX Spectrum compatibles, with more advanced systems also offering expanded versions like 128K BASIC, +3 BASIC, T/S 2000 BASIC, BASIC64 or Timex Extended Basic. As of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Imperative Programming
In computer science, imperative programming is a programming paradigm of software that uses statements that change a program's state. In much the same way that the imperative mood in natural languages expresses commands, an imperative program consists of commands for the computer to perform. Imperative programming focuses on describing ''how'' a program operates step by step, rather than on high-level descriptions of its expected results. The term is often used in contrast to declarative programming, which focuses on ''what'' the program should accomplish without specifying all the details of ''how'' the program should achieve the result. Imperative and procedural programming Procedural programming is a type of imperative programming in which the program is built from one or more procedures (also termed subroutines or functions). The terms are often used as synonyms, but the use of procedures has a dramatic effect on how imperative programs appear and how they are constructed ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hello World Program
''Hello'' is a salutation or greeting in the English language. It is first attested in writing from 1826. Early uses ''Hello'', with that spelling, was used in publications in the U.S. as early as the 18 October 1826 edition of the ''Norwich Courier'' of Norwich, Connecticut. Another early use was an 1833 American book called ''The Sketches and Eccentricities of Col. David Crockett, of West Tennessee'', which was reprinted that same year in '' The London Literary Gazette''. The word was extensively used in literature by the 1860s. Etymology According to the ''Oxford English Dictionary'', ''hello'' is an alteration of ''hallo'', ''hollo'', which came from Old High German "''halâ'', ''holâ'', emphatic imperative of ''halôn'', ''holôn'' to fetch, used especially in hailing a ferryman". It also connects the development of ''hello'' to the influence of an earlier form, ''holla'', whose origin is in the French ''holà'' (roughly, 'whoa there!', from French ''là'' 'there'). As i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Memory-mapped I/O
Memory-mapped I/O (MMIO) and port-mapped I/O (PMIO) are two complementary methods of performing input/output (I/O) between the central processing unit (CPU) and peripheral devices in a computer. An alternative approach is using dedicated I/O processors, commonly known as channels on mainframe computers, which execute their own instructions. Memory-mapped I/O uses the same address space to address both main memory and I/O devices. The memory and registers of the I/O devices are mapped to (associated with) address values. So a memory address may refer to either a portion of physical RAM, or instead to memory and registers of the I/O device. Thus, the CPU instructions used to access the memory can also be used for accessing devices. Each I/O device monitors the CPU's address bus and responds to any CPU access of an address assigned to that device, connecting the data bus to the desired device's hardware register. To accommodate the I/O devices, some areas of the address bus use ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
E (mathematical Constant)
The number , also known as Euler's number, is a mathematical constant approximately equal to 2.71828 that can be characterized in many ways. It is the base of the natural logarithms. It is the limit of as approaches infinity, an expression that arises in the study of compound interest. It can also be calculated as the sum of the infinite series e = \sum\limits_^ \frac = 1 + \frac + \frac + \frac + \cdots. It is also the unique positive number such that the graph of the function has a slope of 1 at . The (natural) exponential function is the unique function that equals its own derivative and satisfies the equation ; hence one can also define as . The natural logarithm, or logarithm to base , is the inverse function to the natural exponential function. The natural logarithm of a number can be defined directly as the area under the curve between and , in which case is the value of for which this area equals one (see image). There are various other characteriz ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Radian
The radian, denoted by the symbol rad, is the unit of angle in the International System of Units (SI) and is the standard unit of angular measure used in many areas of mathematics. The unit was formerly an SI supplementary unit (before that category was abolished in 1995). The radian is defined in the SI as being a dimensionless unit, with 1 rad = 1. Its symbol is accordingly often omitted, especially in mathematical writing. Definition One radian is defined as the angle subtended from the center of a circle which intercepts an arc equal in length to the radius of the circle. More generally, the magnitude in radians of a subtended angle is equal to the ratio of the arc length to the radius of the circle; that is, \theta = \frac, where is the subtended angle in radians, is arc length, and is radius. A right angle is exactly \frac radians. The rotation angle (360°) corresponding to one complete revolution is the length of the circumference divided by the radius, which i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Trigonometric Functions
In mathematics, the trigonometric functions (also called circular functions, angle functions or goniometric functions) are real functions which relate an angle of a right-angled triangle to ratios of two side lengths. They are widely used in all sciences that are related to geometry, such as navigation, solid mechanics, celestial mechanics, geodesy, and many others. They are among the simplest periodic functions, and as such are also widely used for studying periodic phenomena through Fourier analysis. The trigonometric functions most widely used in modern mathematics are the sine, the cosine, and the tangent. Their reciprocals are respectively the cosecant, the secant, and the cotangent, which are less used. Each of these six trigonometric functions has a corresponding inverse function, and an analog among the hyperbolic functions. The oldest definitions of trigonometric functions, related to right-angle triangles, define them only for acute angles. To extend the sine and cos ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
ZX Spectrum Character Set
The ZX Spectrum character set is the variant of ASCII used in the ZX Spectrum family computers. It is based on ASCII-1967 but the characters ^, ` and DEL are replaced with ↑, £ and ©. It also differs in its use of the C0 control codes other than the common BS and CR, and it makes use of the 128 high-bit characters beyond the ASCII range.ZX Spectrum manual, Appendix A, the character set The ZX Spectrum's main set of printable characters and system font are also used by the Jupiter Ace computer. Printable characters Standard US-ASCII, 0x20–0x7F, is included in the Spectrum character set except that code point 0x5E is an up-arrow (↑) instead of a caret (^), 0x60 is the pound sign (£) instead of the grave accent (`), and 0x7F is the copyright sign (©) instead of the control character DEL. Note that the use of 0x5E as ↑ was also the case in the older 1963 version of ASCII. The £ sign was not mapped to 0x23 as in the British variant of ASCII ( ISO-646-GB), allowing bo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
ZX Microdrive
ZX Microdrive unit 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 faster-loading alternative to the cassette and cheaper than a floppy disk, but it suffered from poor reliability and lower speed. Microdrives used tiny cartridges containing a endless loop of magnetic tape, which held a minimum of 85 kB and performed a complete circuit in approximately eight seconds. The Microdrive technology was later also used in the Sinclair QL and ICL One Per Desk personal computers. Development Microdrive cartridge with case It is claimed the Microdrive concept was originally 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, and neve ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Binary Number
A binary number is a number expressed in the base-2 numeral system or binary numeral system, a method of mathematical expression which uses only two symbols: typically "0" (zero) and "1" ( one). The base-2 numeral system is a positional notation with a radix of 2. Each digit is referred to as a bit, or binary digit. Because of its straightforward implementation in digital electronic circuitry using logic gates, the binary system is used by almost all modern computers and computer-based devices, as a preferred system of use, over various other human techniques of communication, because of the simplicity of the language and the noise immunity in physical implementation. History The modern binary number system was studied in Europe in the 16th and 17th centuries by Thomas Harriot, Juan Caramuel y Lobkowitz, and Gottfried Leibniz. However, systems related to binary numbers have appeared earlier in multiple cultures including ancient Egypt, China, and India. Leibniz was specifica ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Middle C
C or Do is the first note and semitone of the C major scale, the third note of the A minor scale (the relative minor of C major), and the fourth note (G, A, B, C) of the Guidonian hand, commonly pitched around 261.63 Hz. The actual frequency has depended on historical pitch standards, and for transposing instruments a distinction is made between written and sounding or concert pitch. It has enharmonic equivalents of B and D. In English the term ''Do'' is used interchangeably with C only by adherents of fixed Do solfège; in the movable Do system Do refers to the tonic of the prevailing key. Frequency Historically, concert pitch has varied. For an instrument in equal temperament tuned to the A440 pitch standard widely adopted in 1939, middle C has a frequency around 261.63 Hz (for other notes see piano key frequencies). Scientific pitch was originally proposed in 1713 by French physicist Joseph Sauveur and based on the numerically convenient frequency of 256 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Semitone
A semitone, also called a half step or a half tone, is the smallest musical interval commonly used in Western tonal music, and it is considered the most dissonant when sounded harmonically. It is defined as the interval between two adjacent notes in a 12-tone scale. For example, C is adjacent to C; the interval between them is a semitone. In a 12-note approximately equally divided scale, any interval can be defined in terms of an appropriate number of semitones (e.g. a whole tone or major second is 2 semitones wide, a major third 4 semitones, and a perfect fifth 7 semitones. In music theory, a distinction is made between a diatonic semitone, or minor second (an interval encompassing two different staff positions, e.g. from C to D) and a chromatic semitone or augmented unison (an interval between two notes at the same staff position, e.g. from C to C). These are enharmonically equivalent when twelve-tone equal temperament is used, but are not the same thing in meantone temper ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Byte
The byte is a unit of digital information that most commonly consists of eight bits. Historically, the byte was the number of bits used to encode a single character of text in a computer and for this reason it is the smallest addressable unit of memory in many computer architectures. To disambiguate arbitrarily sized bytes from the common 8-bit definition, network protocol documents such as The Internet Protocol () refer to an 8-bit byte as an octet. Those bits in an octet are usually counted with numbering from 0 to 7 or 7 to 0 depending on the bit endianness. The first bit is number 0, making the eighth bit number 7. The size of the byte has historically been hardware-dependent and no definitive standards existed that mandated the size. Sizes from 1 to 48 bits have been used. The six-bit character code was an often-used implementation in early encoding systems, and computers using six-bit and nine-bit bytes were common in the 1960s. These systems often had memory words ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
