Computer program

[4] If the source code is requested for execution, then the operating system loads the corresponding interpreter into memory and starts a process.

[14] The description contained Note G which completely detailed a method for calculating Bernoulli numbers using the Analytical Engine.

[18] Its 40 units weighed 30 tons, occupied 1,800 square feet (167 m2), and consumed $650 per hour (in 1940s currency) in electricity when idle.

[19] It ran from 1947 until 1955 at Aberdeen Proving Ground, calculating hydrogen bomb parameters, predicting weather patterns, and producing firing tables to aim artillery guns.

[28] A major milestone in software development was the invention of the Very Large Scale Integration (VLSI) circuit (1964).

[29] Robert Noyce, co-founder of Fairchild Semiconductor (1957) and Intel (1968), achieved a technological improvement to refine the production of field-effect transistors (1963).

For example, the IBM System/360 (1964) had a CPU made from circuit boards containing discrete components on ceramic substrates.

[40] A programming language is a set of keywords, symbols, identifiers, and rules by which programmers can communicate instructions to the computer.

[42] The purpose of defining a solution in terms of its formal language is to generate an algorithm to solve the underlining problem.

Imperative languages specify a sequential algorithm using declarations, expressions, and statements:[52] FORTRAN (1958) was unveiled as "The IBM Mathematical FORmula TRANslating system".

[57] Emerging from a committee of European and American programming language experts, it used standard mathematical notation and had a readable, structured design.

It added features like: Algol's direct descendants include Pascal, Modula-2, Ada, Delphi and Oberon on one branch.

Therefore, the following expression will return the list x: cons(head(x), tail(x)) One drawback of Lisp is when many functions are nested, the parentheses may look confusing.

[84] Whereas dynamic binding increases the language's flexibility, programming errors may linger until late in the software development process.

It is an implementation of Selective Linear Definite clause resolution, pioneered by Robert Kowalski and others at the University of Edinburgh.

Here is a C programming language header file for the GRADE abstract datatype in a simple school application: The grade_new() function performs the same algorithm as the C++ constructor operation.

Here is a C programming language source file for the GRADE abstract datatype in a simple school application: In the constructor, the function calloc() is used instead of malloc() because each memory cell will be set to zero.

In a formal environment, a systems analyst will gather information from managers about all the organization's processes to automate.

[111] As the waterfall label implies, the basic phases overlap each other:[112] A computer programmer is a specialist responsible for writing or modifying the source code to implement the detailed plan.

[122] The purpose of the operating system is to provide an environment where application software executes in a convenient and efficient manner.

The potential advantages of off-the-shelf software are upfront costs are identifiable, the basic needs should be fulfilled, and its performance and reliability have a track record.

The biggest advantage is it frees in-house resources from staffing and managing complex computer projects.

[129] Many application service providers target small, fast-growing companies with limited information system resources.

[129] An operating system is the low-level software that supports a computer's basic functions, such as scheduling processes and controlling peripherals.

After the program finished executing, the output may have been printed, or it may have been punched onto paper tape or cards for later processing.

Operating systems execute hardware utility programs to check the status of disk drives, memory, speakers, and printers.

)[142] Microcode instructions allow the programmer to more easily implement the digital logic level[143]—the computer's real hardware.

Microcode instructions are mnemonics programmers may use to execute digital logic functions instead of forming them in binary algebra.

The micro-instruction cycle begins when the microsequencer uses its microprogram counter to fetch the next machine instruction from random-access memory.

[147] The next step is to decode the machine instruction by selecting the proper output line to the hardware module.