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Date (Unix Command)
In computer science and computer programming, system time represents a computer system's notion of the passage of time. In this sense, ''time'' also includes the passing of days on the calendar. System time is measured by a ''system clock'', which is typically implemented as a simple count of the number of ''ticks'' that have transpired since some arbitrary starting date, called the ''epoch''. For example, Unix and POSIX-compliant systems encode system time ("Unix time") as the number of seconds elapsed since the start of the Unix epoch at 1 January 1970 00:00:00 UT, with exceptions for leap seconds. Systems that implement the 32-bit and 64-bit versions of the Windows API, such as Windows 9x and Windows NT, provide the system time as both , represented as a year/month/day/hour/minute/second/milliseconds value, and , represented as a count of the number of 100-nanosecond ticks since 1 January 1601 00:00:00 UT as reckoned in the proleptic Gregorian calendar. System time can be ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Unix Time
Unix time is a date and time representation widely used in computing. It measures time by the number of non-leap seconds that have elapsed since 00:00:00 Coordinated Universal Time, UTC on 1 January 1970, the Unix Epoch (computing), epoch. For example, at midnight on 1 January 2010, Unix time was 1262304000. Unix time originated as the system time of Unix operating systems. It has come to be widely used in other computer operating systems, file systems, programming languages, and databases. In modern computing, values are sometimes stored with higher Data granularity, granularity, such as microseconds or nanoseconds. Definition Unix time is currently defined as the number of non-leap seconds which have passed since 00:00:00UTC on Thursday, 1 January 1970, which is referred to as the ''Unix epoch (computing), epoch''. Unix time is typically encoded as a signed integer. The Unix time is exactly midnight UTC on 1 January 1970, with Unix time incrementing by 1 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Locale (computer Software)
In computing, a locale is a set of parameters that defines the user's language, region and any special variant preferences that the user wants to see in their user interface. Usually a locale identifier consists of at least a language code and a country/region code. Locale is an important aspect of i18n. General locale settings These settings usually include the following display (output) format settings: * Number format setting (LC_NUMERIC, C/C++) * Character classification, case conversion settings (LC_CTYPE, C/C++) * Date-time format setting (LC_TIME, C/C++) * String collation setting (LC_COLLATE, C/C++) * Currency format setting (LC_MONETARY, C/C++) * Paper size setting (LC_PAPER, ISO 30112) * Color temperature setting * UI font setting (especially for CJKV language) * Location setting (country or region) * ANSI character set setting (for Microsoft Windows) The locale settings are about formatting output given a locale. So, the time zone information and daylight saving ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Timestamp
A timestamp is a sequence of characters or encoded information identifying when a certain event occurred, usually giving date and time of day, sometimes accurate to a small fraction of a second. Timestamps do not have to be based on some absolute notion of time, however. They can have any epoch, can be relative to any arbitrary time, such as the power-on time of a system, or to some arbitrary time in the past. A distinction is sometimes made between the terms datestamp, timestamp and date-timestamp: * Datestamp or DS: A date, for example -- according to ISO 8601 * Timestamp or TS: A time of day, for example :: using 24-hour clock * Date-timestamp or DTS: Date and time, for example --, :: History The term "timestamp" derives from rubber stamps used in offices to stamp the current date, and sometimes time, in ink on paper documents, to record when the document was received. Common examples of this type of timestamp are a postmark on a letter or the "in" and "out" times on a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Elapsed Real Time
In computing, elapsed real time, real time, wall-clock time, wall time, or walltime is the actual time taken from the start of a computer program to the end. In other words, it is the difference between the time at which a task finishes and the time at which the task started. Wall time is thus different from '' CPU time'', which measures only the time during which the processor is actively working on a certain task or process. The difference between the two can arise from architecture and run-time dependent factors, e.g. programmed delays or waiting for system resources to become available. Consider the example of a mathematical program that reports that it has used "CPU time 0m0.04s, Wall time 6m6.01s". This means that while the program was active for six minutes and one second, during that time the computer's processor spent only 4/100 of a second performing calculations for the program. Conversely, programs running in parallel on more than one processing unit can spend CPU ... [...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'') is an electronic logic signal (voltage or current) which oscillates between a high and a low state at a constant frequency and is used like a metronome to synchronize actions of digital circuits. In a synchronous logic circuit, the most common type of digital circuit, the clock signal is applied to all storage devices, flip-flops and latches, and causes them all to change state simultaneously, preventing race conditions. A clock signal is produced by an electronic oscillator called a clock generator. The most common clock signal is in the form of a square wave with a 50% duty cycle. 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 suffi ... [...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 Program counter The program counter (PC) is a register that holds the memory address of the next instruction to be executed. After each instruction copy to the memory address register (MAR), the PC can ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kernel (operating System)
A kernel is a computer program at the core of a computer's operating system that always has complete control over everything in the system. The kernel is also responsible for preventing and mitigating conflicts between different processes. It is the portion of the operating system code that is always resident in memory and facilitates interactions between hardware and software components. A full kernel controls all hardware resources (e.g. I/O, memory, cryptography) via device drivers, arbitrates conflicts between processes concerning such resources, and optimizes the use of common resources, such as CPU, cache, file systems, and network sockets. On most systems, the kernel is one of the first programs loaded on startup (after the bootloader). It handles the rest of startup as well as memory, peripherals, and input/output (I/O) requests from software, translating them into data-processing instructions for the central processing unit. The critical code of the kernel is usua ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Process (computing)
In computing, a process is the Instance (computer science), instance of a computer program that is being executed by one or many thread (computing), threads. There are many different process models, some of which are light weight, but almost all processes (even entire virtual machines) are rooted in an operating system (OS) process which comprises the program code, assigned system resources, physical and logical access permissions, and data structures to initiate, control and coordinate execution activity. Depending on the OS, a process may be made up of multiple threads of execution that execute instructions Concurrency (computer science), concurrently. While a computer program is a passive collection of Instruction set, instructions typically stored in a file on disk, a process is the execution of those instructions after being loaded from the disk into memory. Several processes may be associated with the same program; for example, opening up several instances of the same progra ... [...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] |
CPU Time
CPU time (or process time) is the amount of time that a central processing unit (CPU) was used for processing instructions of a computer program or operating system. CPU time is measured in clock ticks or seconds. Sometimes it is useful to convert CPU time into a percentage of the CPU capacity, giving the CPU usage. Measuring CPU time for two functionally identical programs that process identical inputs can indicate which program is faster, but it is a common misunderstanding that CPU time can be used to compare ''algorithms''. Comparing programs by their CPU time compares specific ''implementations'' of algorithms. (It is possible to have both efficient and inefficient implementations of the same algorithm.) Algorithms are more commonly compared using measures of time complexity and space complexity. Typically, the CPU time used by a program is measured by the operating system, which schedules all of the work of the CPU. Modern multitasking operating systems run hundreds ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
File Format
A file format is a Computer standard, standard way that information is encoded for storage in a computer file. It specifies how bits are used to encode information in a digital storage medium. File formats may be either proprietary format, proprietary or open format, open. Some file formats are designed for very particular types of data: Portable Network Graphics, PNG files, for example, store Raster graphics, bitmapped Graphics file format, images using lossless data compression. Other file formats, however, are designed for storage of several different types of data: the Ogg format can act as a container format (digital), container for different types of multimedia including any combination of sound, audio and video, with or without text (such as subtitles), and metadata. A text file can contain any stream of characters, including possible control characters, and is encoded in one of various Character encoding, character encoding schemes. Some file formats, such as HTML, sca ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
