A branch (or jump on some computer architectures, such as the PDP-8 and Intel x86) is a point in a computer program where the flow of control is altered. The term branch is usually used when referring to a program written in machine code or assembly language; in a high-level programming language, branches usually take the form of conditional statements, subroutine calls or GOTO statements. An instruction that causes a branch, a branch instruction, can be taken or not taken: if a branch is not taken, the flow of control is unchanged and the next instruction to be executed is the instruction immediately following the current instruction in memory; if taken, the next instruction to be executed is an instruction at some other place in memory. There are two usual forms of branch instruction: a conditional branch that can be either taken or not taken, depending on a condition such as a CPUflag, and an unconditional branch which is always taken. Computer architecture is the theory behind the design of a computer. ... A PDP-8 on display at the Smithsonians National Museum of American History in Washington, D.C.. This example is from the first generation of PDP-8s, built with discrete transistors and later known as the Straight 8. ... x86 or 80x86 is the generic name of a microprocessor architecture first developed and manufactured by Intel. ... A computer program is a collection of instructions that describe a task, or set of tasks, to be carried out by a computer. ... In computer science control flow (or alternatively, flow of control) refers to the order in which the individual statements, instructions or function calls of an imperative or functional program are executed or evaluated. ... Machine code or machine language is a system of instructions and data directly understandable by a computers central processing unit. ... See the terminology section, below, regarding inconsistent use of the terms assembly and assembler. ... A high-level programming language is a programming language that, in comparison to low-level programming languages, may be more abstract, easier to use, or more portable across platforms. ... In computer science, conditional statements are a vital part of a programming language. ... In computer science, a subroutine (function, method, procedure, or subprogram) is a portion of code within a larger program, which performs a specific task and is relatively independent of the remaining code. ... GOTO is a statement found in many computer programming languages. ... To meet Wikipedias quality standards, this article or section may require cleanup. ... Die of an Intel 80486DX2 microprocessor (actual size: 12×6. ... In computer programming, flag refers to one or more bits that are used to store a binary value or code that has an assigned meaning. ...
Examples
An unconditional branch in Intel assembly language:
Computerscience overlapped considerably during this time with the branch of mathematics known as numerical analysis, which examines the accuracy and precision of calculations.
As the use of computers expanded between the 1950s and the 1970s, the focus of computerscience broadened to include simplifying the use of computers through programming languages—artificial languages used to program computers, and operating systems—computer programs that provide a useful interface between a computer and a user.
Computerscience can be divided into four main fields: software development, computer architecture (hardware), human-computer interfacing (the design of the most efficient ways for humans to use computers), and artificial intelligence (the attempt to make computers behave intelligently).
Computer scientists are interested in making operating systems easier to use, more secure, and more efficient by developing new user interface designs, designing new mechanisms that allow data to be shared while preventing access to sensitive data, and developing algorithms that make more effective use of the computer’s time and memory.
Computer architects study ways of improving computers by increasing their speed, storage capacity, and reliability, and by reducing their cost and power consumption.
Examples include improving computer access for people with disabilities, simplifying program use, developing three-dimensional input and output devices for virtual reality, improving handwriting and speech recognition, and developing heads-up displays for aircraft instruments in which critical information such as speed, altitude, and heading are displayed on a screen in front of the pilot’s window.
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