A computer performs computations and makes logical decisions. The elements of a computer are hardware, programs, and software. Hardware makes up the physical devices of a computer system. Programs are a set of instructions by which a computer processes data, and software is the collection of bundled programs to be executed by the user.
A computer is organized into several units.
- An input unit is an external piece of hardware allowing users to send commands to the computer (e.g. through a keyboard or mouse).
- In order to create a feedback loop with the computer we must have outputs as well, e.g. through a monitor, speakers, headphones, or even a printer. These devices allow the computer to output the user input in visual and auditory terms.
- In order for the computer to keep track of the user input, a memory unit is required to store or process information. Information is stored on the computer only temporarily and won’t remain on the computer in ling term.
- The arithmetic logic unit (ALU) and the central processing unit (CPU) are the units which perform calculations. The ALU performs arithmetic and logic operations, while the CPU supervisors the operation of all devices
- In order to store software, programs, and other data for the long term, a secondary storage unit is required.
The booting process is the process by which a machine comes from its rest state to a usable state.
During the boot process there are several units involved that have a specific order.
- The machine is powered on by the user with an on/off switch on the computer, after which the CPU runs the BIOS (= Basic Input/Output System).
- The BIOS is responsible for loading the sector program, which in turn loads the OS (operating system) files into the RAM (Random Access Memory).
- The operating system configures the hardware to prepare for input and output. The boot process is complete when the computer waits for the user to issue commands.