Computer Architecture CEdu581 Week 4

Describe what actions a computer takes from power-on to Log-in screen.

Source: http://computer.howstuffworks.com/pc3.htm

As soon as power is fed to the computer with the On button being pushed the Basic Input Output System (BIOS) is started. On older model computers the BIOS information is displayed on the screen in text. New computers have sped up the process and eliminated the text. The BIOS will check the viability of various components of the computer in what is called the power-on self test (POST) This starts at the the video card.

The BIOS will also check if the computer is restarting or cold booting. If it is a restart the BIOS will skip many of the next processes. If it is a cold startup the computer will check the RAM, to ensure viability. It will also check the mouse, keyboard and any other peripherals that may be connected.

The next step is the hard drive. The BIOS will look for the boot drive where the operating system is located. The boot drive loads the OS and operations are handed over to the OS.

What are the essential "big picture" hardware pieces a computer must have to be a computer. Explain why each piece is essential.

A computer needs:

Central Process Unit: Makes all the decisions for the computer using arithmetic/logic decisions. Instructions are brought to the CPU from the memory, interpreted and executed.

Memory: There are two kinds of memory in the computer. RAM or Random Access Memory and Hard Drive Memory. The RAM is used to store short term information for the CPU. The more RAM that is available the quicker the CPU can work. The HD Memory stores programs and the operating system. These are collections of instructions that the CPU executes to perform the functions of the computer. Without HD memory when the computer is shut off the RAM is wiped clean and everything will be forgotten.

Input: Inputs are ways of getting instruction and data into the computer. This includes but is not limited to keyboards, mice and disk drives.

Output: The computer will perform actions based on instructions executed. The output displays the results. Outputs most notably include monitors that display a graphical user interface but outputs are also speakers and other devices.