1_understanding_a_computer.Rmd

title: Understanding a computer
author: "Laurent Modolo"

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Objective: understand the relations between the different components of a computer

Which parts are necessary to define a computer ?

Computer components

CPU (Central Processing Unit)

Memory

RAM (Random Access Memory)

HDD (Hard Disk Drive) / SSD (Solid-State Drive)

Motherboard

GPU (Graphical Processing Unit)

Alimentation

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Computer model: universal Turing machine

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As simple as a Turing machine ?

• A tape divided into cells, one next to the other. Each cell contains a symbol from some finite alphabet.
• A head that can read and write symbols on the tape and move the tape left and right one (and only one) cell at a time.
• A state register that stores the state of the Turing machine, one of finitely many. Among these is the special start state with which the state register is initialized.
• A finite table of instructions that, given the state the machine is currently in and the symbol it is reading on the tape, tells the machine what to do.

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Basic Input Output System (BIOS)

Used to perform hardware initialization during the booting process (power-on startup), and to provide runtime services for operating systems and programs.

• comes pre-installed on a personal computer's system board
• the first software to run when powered on
• in modern PCs initializes and tests the system hardware components, and loads a boot loader from a mass memory device