page_title: Booting
section_title: History
hierarchical_section_title: Booting / History
caption_attribution_description: English: ENIAC (Electronic Numerical Integrator And Computer) in Philadelphia, Pennsylvania. Glen Beck (background) and Betty Snyder (foreground) program the ENIAC in building 328 at the Ballistic Research Laboratory (BRL).
context_page_description: In computing, booting is the process of starting a computer. It can be initiated by hardware such as a button press, or by a software command. After it is switched on, a computer's central processing unit has no software in its main memory, so some process must load software into memory before it can be executed. This may be done by hardware or firmware in the CPU, or by a separate processor in the computer system.
  Restarting a computer also is called rebooting, which can be "hard", e.g. after electrical power to the CPU is switched from off to on, or "soft", where the power is not cut. On some systems, a soft boot may optionally clear RAM to zero. Both hard and soft booting can be initiated by hardware such as a button press or by software command. Booting is complete when the operative runtime system, typically operating system and some applications, is attained.
  The process of returning a computer from a state of hibernation or sleep does not involve booting. Minimally, some embedded systems do not require a noticeable boot sequence to begin functioning and when turned on may simply run operational programs that are stored in ROM.
context_section_description: There are many different methods available to load a short initial program into a computer. These methods reach from simple, physical input to removable media that can hold more complex programs.
caption: Switches and cables used to program ENIAC (1946)
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