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Contended Memory
Contended memory is Sinclair's name for a portion of the ZX Spectrum's 64 KB addressable memory space. With the full 64 KB, the Z80 microprocessor is the exclusive bus master, so it reads and writes operate at its full bus speed, but contended memory space is shared between the ULA and the Z80, with the ULA having higher priority. Contended memory occupies addresses 0x4000..0x7FFF of the Z80 memory map. This is the first 16 KB of RAM in the 48 KB machine and the entire RAM of the 16 KB machine. Contention occurs as a result of the ULA reading the display and attributes data in this RAM to produce the TV video display. Contention therefore does not occur during horizontal flyback, vertical flyback or during the screen border. Accesses to I/O also contend if the ULA must read contended memory while the Z80 accesses a ULA I/O port. ULA I/O ports are those with an even address (address bit 0 is a 0). The Z80 must wait whenever the ULA needs to access contended memory before procee ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sinclair Research
Sinclair Research Ltd is a British consumer electronics company founded by Clive Sinclair in Cambridge. It was originally incorporated in 1973 as Westminster Mail Order Ltd, renamed Sinclair Instrument Ltd, then Science of Cambridge Ltd, then Sinclair Computers Ltd, and finally 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, and 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, and competing aggressively against Commodore and Amstrad. At the height of its success, and largely inspired by the Japanese Fifth Generation Computer program, the company established the "MetaLab" research centre at Milton Hall near Cambrid ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Instruction Cycle
The instruction cycle (also known as the fetch–decode–execute cycle, or simply the fetch-execute cycle) is the cycle that the central processing unit (CPU) follows from boot-up until the computer has shut down in order to process instructions. It is composed of three main stages: the fetch stage, the decode stage, and the execute stage. In simpler CPUs, the instruction cycle is executed sequentially, each instruction being processed before the next one is started. In most modern CPUs, the instruction cycles are instead executed concurrently, and often in parallel, through an instruction pipeline: the next instruction starts being processed before the previous instruction has finished, which is possible because the cycle is broken up into separate steps. Role of components The program counter (PC) is a special register that holds the memory address of the next instruction to be executed. During the fetch stage, the address stored in the PC is copied into the memory addres ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Software Bug
A software bug is an error, flaw or fault in the design, development, or operation of computer software that causes it to produce an incorrect or unexpected result, or to behave in unintended ways. The process of finding and correcting bugs is termed " debugging" and often uses formal techniques or tools to pinpoint bugs. Since the 1950s, some computer systems have been designed to deter, detect or auto-correct various computer bugs during operations. Bugs in software can arise from mistakes and errors made in interpreting and extracting users' requirements, planning a program's design, writing its source code, and from interaction with humans, hardware and programs, such as operating systems or libraries. A program with many, or serious, bugs is often described as ''buggy''. Bugs can trigger errors that may have ripple effects. The effects of bugs may be subtle, such as unintended text formatting, through to more obvious effects such as causing a program to crash, freezing th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Special Effect
Special effects (often abbreviated as SFX, F/X or simply FX) are illusions or visual tricks used in the theatre, film, television, video game, amusement park and simulator industries to simulate the imagined events in a story or virtual world. Special effects are traditionally divided into the categories of mechanical effects and optical effects. With the emergence of digital film-making a distinction between special effects and visual effects has grown, with the latter referring to digital post-production and optical effects, while "special effects" refers to mechanical effects. Mechanical effects (also called practical or physical effects) are usually accomplished during the live-action shooting. This includes the use of mechanized props, scenery, scale models, animatronics, pyrotechnics and atmospheric effects: creating physical wind, rain, fog, snow, clouds, making a car appear to drive by itself and blowing up a building, etc. Mechanical effects are also often inco ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Video Game
Video games, also known as computer games, are electronic games that involves interaction with a user interface or input device such as a joystick, controller, keyboard, or motion sensing device to generate visual feedback. This feedback mostly commonly is shown on a video display device, such as a TV set, monitor, touchscreen, or virtual reality headset. Some computer games do not always depend on a graphics display, for example text adventure games and computer chess can be played through teletype printers. Video games are often augmented with audio feedback delivered through speakers or headphones, and sometimes with other types of feedback, including haptic technology. Video games are defined based on their platform, which include arcade video games, console games, and personal computer (PC) games. More recently, the industry has expanded onto mobile gaming through smartphones and tablet computers, virtual and augmented reality systems, and remote c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Noise (signal Processing)
In signal processing, noise is a general term for unwanted (and, in general, unknown) modifications that a signal (signal processing), signal may suffer during capture, storage, transmission, processing, or conversion. Vyacheslav Tuzlukov (2010), ''Signal Processing Noise'', Electrical Engineering and Applied Signal Processing Series, CRC Press. 688 pages. Sometimes the word is also used to mean signals that are Randomness, random (Predictability, unpredictable) and carry no useful information; even if they are not interfering with other signals or may have been introduced intentionally, as in comfort noise. Noise reduction, the recovery of the original signal from the noise-corrupted one, is a very common goal in the design of signal processing systems, especially filter (signal processing), filters. The mathematical limits for noise removal are set by information theory. Types of noise Signal processing noise can be classified by its statistical properties (sometimes ca ... [...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] |
Video
Video is an electronic medium for the recording, copying, playback, broadcasting, and display of moving visual media. Video was first developed for mechanical television systems, which were quickly replaced by cathode-ray tube (CRT) systems which, in turn, were replaced by flat panel displays of several types. Video systems vary in display resolution, aspect ratio, refresh rate, color capabilities and other qualities. Analog and digital variants exist and can be carried on a variety of media, including radio broadcast, magnetic tape, optical discs, computer files, and network streaming. History Analog video Video technology was first developed for mechanical television systems, which were quickly replaced by cathode-ray tube (CRT) television systems, but several new technologies for video display devices have since been invented. Video was originally exclusively a live technology. Charles Ginsburg led an Ampex research team developing one of the first practical vi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Interrupt Vector Table
An interrupt vector table (IVT) is a data structure that associates a list of interrupt handlers with a list of interrupt requests in a table of interrupt vectors. Each entry of the interrupt vector table, called an interrupt vector, is the address of an interrupt handler. While the concept is common across processor architectures, IVTs may be implemented in architecture-specific fashions. For example, a dispatch table is one method of implementing an interrupt vector table. Background Most processors have an interrupt vector table, including chips from Intel, AMD, Infineon, Microchip Atmel, NXP, ARM etc. Interrupt handlers Handling methods An interrupt vector table is used in the three most popular methods of finding the starting address of the interrupt service routine: "Predefined" The "predefined" method loads the program counter (PC) directly with the address of some entry inside the interrupt vector table. The jump table itself contains executable code. While in p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Programmer
A computer programmer, sometimes referred to as a software developer, a software engineer, a programmer or a coder, is a person who creates computer programs — often for larger computer software. A programmer is someone who writes/creates computer software or applications by providing a specific programming language to the computer. Most programmers have extensive computing and coding experience in many varieties of programming languages and platforms, such as Structured Query Language (SQL), Perl, Extensible Markup Language (XML), PHP, HTML, C, C++ and Java. A programmer's most often-used computer language (e.g., Assembly, C, C++, C#, JavaScript, Lisp, Python, Java, etc.) may be prefixed to the aforementioned terms. Some who work with web programming languages may also prefix their titles with ''web''. Terminology There is no industry-wide standard terminology, so "programmer" and "software engineer" might refer to the same role at different companies. Most typically, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Clock Signal
In electronics and especially synchronous digital circuits, a clock signal (historically also known as ''logic beat'') oscillates between a high and a low state and is used like a metronome to coordinate actions of digital circuits. A clock signal is produced by a clock generator. Although more complex arrangements are used, the most common clock signal is in the form of a square wave with a 50% duty cycle, usually with a fixed, constant frequency. Circuits using the clock signal for synchronization may become active at either the rising edge, falling edge, or, in the case of double data rate, both in the rising and in the falling edges of the clock cycle. Digital circuits Most integrated circuits (ICs) of sufficient complexity use a clock signal in order to synchronize different parts of the circuit, cycling at a rate slower than the worst-case internal propagation delays. In some cases, more than one clock cycle is required to perform a predictable action. As ICs become mo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
ZX Spectrum
The ZX Spectrum () is an 8-bit computing, 8-bit home computer that was developed by Sinclair Research. It was released in the United Kingdom on 23 April 1982, and became Britain's best-selling microcomputer. Referred to during development as the ''ZX81 Colour'' and ''ZX82'', it was launched as the ''ZX Spectrum'' to highlight the machine's colour display, which differed from the black and white display of its predecessor, the ZX81. The Spectrum was released as six different models, ranging from the entry level with 16 Kilobyte, KB RAM released in 1982 to the ZX Spectrum +3 with 128 KB RAM and built in floppy disk drive in 1987; altogether they sold over 5 million units worldwide (not counting List of ZX Spectrum clones, unofficial clones). The Spectrum was among the first home computers in the United Kingdom aimed at a mainstream audience, and it thus had similar significance to the Commodore 64 in the US and the Thomson MO5 in France. The introduction of the ZX Spect ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
