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Heisenbug
In computer programming jargon, a heisenbug is a software bug that seems to disappear or alter its behavior when one attempts to study it. The term is a pun on the name of Werner Heisenberg, the physicist who first asserted the observer effect of quantum mechanics, which states that the act of observing a system inevitably alters its state. In electronics, the traditional term is probe effect, where attaching a test probe to a device changes its behavior. Similar terms, such as ''bohrbug'', ''mandelbug'', ''hindenbug'', and ''schrödinbug'' (see the section on related terms) have been occasionally proposed for other kinds of unusual software bugs, sometimes in jest. Examples Heisenbugs occur because common attempts to debug a program, such as inserting output statements or running it with a debugger, usually have the side-effect of altering the behavior of the program in subtle ways, such as changing the memory addresses of variables and the timing of its execution. One comm ... [...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] |
Computer Programming
Computer programming is the process of performing a particular computation (or more generally, accomplishing a specific computing result), usually by designing and building an executable computer program. Programming involves tasks such as analysis, generating algorithms, profiling algorithms' accuracy and resource consumption, and the implementation of algorithms (usually in a chosen programming language, commonly referred to as coding). The source code of a program is written in one or more languages that are intelligible to programmers, rather than machine code, which is directly executed by the central processing unit. The purpose of programming is to find a sequence of instructions that will automate the performance of a task (which can be as complex as an operating system) on a computer, often for solving a given problem. Proficient programming thus usually requires expertise in several different subjects, including knowledge of the application domain, specialized algori ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Alpha Particle
Alpha particles, also called alpha rays or alpha radiation, consist of two protons and two neutrons bound together into a particle identical to a helium-4 nucleus. They are generally produced in the process of alpha decay, but may also be produced in other ways. Alpha particles are named after the first letter in the Greek alphabet, α. The symbol for the alpha particle is α or α2+. Because they are identical to helium nuclei, they are also sometimes written as or indicating a helium ion with a +2 charge (missing its two electrons). Once the ion gains electrons from its environment, the alpha particle becomes a normal (electrically neutral) helium atom . Alpha particles have a net spin of zero. Due to the mechanism of their production in standard alpha radioactive decay, alpha particles generally have a kinetic energy of about 5 MeV, and a velocity in the vicinity of 4% of the speed of light. (See discussion below for the limits of these figures in alpha decay.) They are ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Soft Error
In electronics and computing, a soft error is a type of error where a signal or datum is wrong. Errors may be caused by a defect, usually understood either to be a mistake in design or construction, or a broken component. A soft error is also a signal or datum which is wrong, but is not assumed to imply such a mistake or breakage. After observing a soft error, there is no implication that the system is any less reliable than before. One cause of soft errors is single event upsets from cosmic rays. In a computer's memory system, a soft error changes an instruction in a program or a data value. Soft errors typically can be remedied by cold booting the computer. A soft error will not damage a system's hardware; the only damage is to the data that is being processed. There are two types of soft errors, ''chip-level soft error'' and ''system-level soft error''. Chip-level soft errors occur when particles hit the chip, e.g., when secondary particles from cosmic rays land on the s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lunar Phase
Concerning the lunar month of ~29.53 days as viewed from Earth, the lunar phase or Moon phase is the shape of the Moon's directly sunlit portion, which can be expressed quantitatively using areas or angles, or described qualitatively using the terminology of the 4 major phases: new moon, first quarter, full moon, last quarter and 4 minor phases: waxing crescent, waxing gibbous, waning gibbous, and waning crescent. The lunar phases gradually change over a synodic month (~29.53 days) as the Moon's orbital positions around Earth and Earth around the Sun shift. The visible side of the Moon is variously sunlit, depending on the position of the Moon in its orbit. Thus, this face's sunlit portion can vary from 0% (at new moon) to 100% (at full moon). Each of the 4 major lunar phases (see below) is ~7.4 days, with +/− 19 hours in variation (6.58–8.24 days) due to the elliptical shape of the Moon's orbit. Phases of the Moon There are four ''principal'' (primary/major) lunar phase ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Observer Effect (information Technology)
In information technology, the observer effect is the impact on the behaviour of a computer process caused by the act of observing the process while it is running. For example: if a process uses a log file to record its progress, the process could slow down. Furthermore, the act of viewing the file while the process is running could cause an I/O error in the process, which could, in turn, cause it to stop. Another example would be observing the performance of a CPU by running both the observed and observing programs on the same CPU, which will lead to inaccurate results because the observer program itself affects the CPU performance (modern, heavily cached and pipelined CPUs are particularly affected by this kind of observation). The observer effect could either have a positive or negative impact on the computer process behaviour. A positive impact can be software bugs, also known as Heisenbugs, which diminish or change their negative behavior when observation mechanisms, such a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Race Condition
A race condition or race hazard is the condition of an electronics, software, or other system where the system's substantive behavior is dependent on the sequence or timing of other uncontrollable events. It becomes a bug when one or more of the possible behaviors is undesirable. The term ''race condition'' was already in use by 1954, for example in David A. Huffman's doctoral thesis "The synthesis of sequential switching circuits". Race conditions can occur especially in logic circuits, multithreaded, or distributed Distribution may refer to: Mathematics *Distribution (mathematics), generalized functions used to formulate solutions of partial differential equations *Probability distribution, the probability of a particular value or value range of a varia ... software programs. In electronics A typical example of a race condition may occur when a logic gate combines signals that have traveled along different paths from the same source. The inputs to the gate can chan ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Source Code
In computing, source code, or simply code, is any collection of code, with or without comments, written using a human-readable programming language, usually as plain text. The source code of a program is specially designed to facilitate the work of computer programmers, who specify the actions to be performed by a computer mostly by writing source code. The source code is often transformed by an assembler or compiler into binary machine code that can be executed by the computer. The machine code is then available for execution at a later time. Most application software is distributed in a form that includes only executable files. If the source code were included it would be useful to a user, programmer or a system administrator, any of whom might wish to study or modify the program. Alternatively, depending on the technology being used, source code may be interpreted and executed directly. Definitions Richard Stallman's definition, formulated in his 1989 seminal li ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Breakpoint
In software development, a breakpoint is an intentional stopping or pausing place in a program, put in place for debugging purposes. It is also sometimes simply referred to as a pause. More generally, a breakpoint is a means of acquiring knowledge about a program during its execution. During the interruption, the programmer inspects the test environment (general purpose registers, memory, logs, files, etc.) to find out whether the program is functioning as expected. In practice, a breakpoint consists of one or more conditions that determine when a program's execution should be interrupted. Breakpoints were invented for ENIAC, one of the earliest digital computers, by programmer Betty Holberton. In the initial design of ENIAC, program flow was set by plugging cables from one unit to another. To make the program stop at a certain point, a cable was removed, called a ''breakpoint''. Machine breakpoints Early mainframe computers, such as the IBM/360, had console switches/dial ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pointer (computer Programming)
In computer science, a pointer is an object in many programming languages that stores a memory address. This can be that of another value located in computer memory, or in some cases, that of memory-mapped computer hardware. A pointer ''references'' a location in memory, and obtaining the value stored at that location is known as ''dereferencing'' the pointer. As an analogy, a page number in a book's index could be considered a pointer to the corresponding page; dereferencing such a pointer would be done by flipping to the page with the given page number and reading the text found on that page. The actual format and content of a pointer variable is dependent on the underlying computer architecture. Using pointers significantly improves performance for repetitive operations, like traversing iterable data structures (e.g. strings, lookup tables, control tables and tree structures). In particular, it is often much cheaper in time and space to copy and dereference pointers th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fandango On Core
{{Short description, Out-of-bounds pointer effects Fandango on core is a computer programming term for the effects of a pointer running out of bounds, often leading to a core dump, or failures in other seemingly unrelated processes. In extreme situations, ''fandango on core'' may lead to the overwriting of operating system code, possibly causing data loss or system crashes. The advent of protected memory means that while a program cannot overwrite the memory of other programs, a loose pointer can still cause strange behaviour within the application. The term presumably comes from the programmer imagining the program following the wild pointer and dancing a fandango on the core (an older term for memory) of a program. References ''This article or an earlier version of it came from the Jargon File.'' External links Fandango on core entry from the Jargon File The Jargon File is a glossary and usage dictionary of slang used by computer programmers. The original Jargon File was a coll ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Assert
Assertion or assert may refer to: Computing * Assertion (software development), a computer programming technique * assert.h, a header file in the standard library of the C programming language * Assertion definition language, a specification language providing a formal grammar to specify behaviour and interfaces for computer software Logic and language * Logical assertion, a statement that asserts that a certain premise is true * Proof by assertion, an informal fallacy in which a proposition is repeatedly restated * Time of assertion, in linguistics a secondary temporal reference in establishing tense * Assertive, a speech act that commits a speaker to the truth of the expressed proposition Other uses * Assert (horse) Assert (17 April 1979 – 14 September 1995) was an Irish Thoroughbred racehorse and sire. As a two-year-old he was beaten by Golden Fleece on his debut but went on to win the Beresford Stakes. In the following year he won four Group One ... (1979–1995 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
