103a-ae PC Lab
103a-ae Open-it Up! Lab
The main parts inside a computer, and how they work
- the processor
The microprocessor is the brain of the computer. It is located on the motherboard and is connected to the rest of the computer through wires and cables. The microprocessor is also known as the CPU and is a small chip containing millions of tiny transistors, devices that block current in one direction while letting current flow in another direction. The CPU performs the calculations necessary to make the computer work and the transistors in the CPU manipulate the data. The collection of instructions that the CPU processes is implemented as bit patterns, each one has a different meaning when loaded into the instruction register. The first microprocessor was the Intel 4004, introduced in 1971 which could only add and subtract at 4 bits at a time. The speed that the processor can execute an instruction is given in Megahertz (MHz) or millions of cycles per second (one hertz = one cycle per second). In 1974, processors could execute instruction in 2MHz. By 2004 processors were executing programs in 3.6 gigahertz . Today there are many different brands of processors such as a Pentium, a K6, a PowerPC, or a Sparc.
- the memory
The memory of a computer is a temporary electronic storage of information. The memory allows the computer to run faster so that it does not have to constantly retrieve information from the hard drive. The memory works with the computer's operating system (such as Microsoft Windows) to allow for faster performance and functionality. Every time a program is opened or loaded, the information is put into the computer's memory so that it is easier accessed and processed. The bit size of a CPU tells how many bytes of information it can access from memory at the same time. A 16-bit CPU can process 2 bytes at a time (1 byte = 8 bits, so 16 bits = 2 bytes), and a 64-bit CPU can process 8 bytes at a time.
- the disk drive
The disk drive or hard drive is what stores the information in a computer. The disk drive converts information onto a magnetic recording material on a high-precision aluminum or glass disk. The magnetic medium can be easily erased and rewritten, and it will store the information for many years. Most computer's hard disks have a capacity between 10 and 40 gigabytes. The information is stored and retrieved by a read/write head that never actually touches the disk, but instead floats above it as it seeks between all the information. The information is stored in sectors and tracks. Tracks are concentric circles, and sectors are pie-shaped wedges on a track. These clusters of information allow the drive to easily skip over or access information without having to go through all that is stored on the disk before it first.
- the cd-rom
The cd-rom is an optically read disc designed to hold information such as music, reference materials, or computer software. A single CD-ROM can hold around 640 megabytes of data. There are three main parts of the cd-drive which read the cd. A drive motor which spins the disc to rotate between 200 and 500 rpm. A laser which reads the information stored on the cd, and a tracking mechanism which moves the laser assembly so that the laser's beam can follow the spiral track. The laser passes through one layer of the cd, reflects off another, and hits a device that detects changes in light. The bumps reflect light differently the flat areas, and the sensor detects that change. The electronics in the drive interpret the changes to read the data.
- the power-supply
The power supply converts the alternating current (AC) line from an outlet to the direct current (DC) needed by the computer. A small, lightweight transformer in the power supply to do the actual voltage step-down from 110 volts (or 220 in certain countries) to the voltage needed by the particular computer component, usually 3.3- and 5-volts used by digital circuits, and 12-volts used to run motors in disk drives and fans.
- the battery
The battery allows a computer to store information even when the computer powers down. The battery provides uninterrupted power.
- the cables
The cables connect the different parts of the computer with each other, and specifically to the motherboard. They bring bits and information to the different parts of the computer.
Eck, David J. The Most Complex Machine. Natick, MA: A K Peters, 2000. 148+. http://www.factmonster.com/ipka/A0902844.html http://computer.howstuffworks.com/microprocessor.htm http://computer.howstuffworks.com/power-supply1.htm http://computer.howstuffworks.com/computer-memory.htm http://computer.howstuffworks.com/hard-disk8.htm http://computer.howstuffworks.com/pc1.htm http://en.wikipedia.org/wiki/Microprocessor
Cecelia Vayda 9/24/08
- The open but still assembled Dell computer
- The motherboard and power source still connected
- The Floppy Drive
- Although at first, we just removed the floppy drive from the computer and took the back off, in the end we took it apart further to show the mechanics of the floppy drive. We were able to see the spring where the floppy loads, as well as some of the more specific workings of it. If we had a smaller screw driver we would have been able to open it even more, but it was interesting to see just how easily we could take it apart.
- CD Rom
- We were not able to take the CD drive apart nearly as much as the floopy, we were really only able to take the casing off of it.
- The Power Supply
- We were able to, with some force, take the cover off the power supply. This allowed us to remove the plug and fan as well as to see some of the more specific parts of the power supply. We were not able to take the cover fully off, and it was interesting to see how much harder it was to take the power supply apart than other parts of the computer.
- The Hard Disk
- We were able to take the hard disk apart quite easily once we applied a little pressure and had a smaller screwdriver. It was interesting to see the actual disk and reader. Ours had three layers of disks that you could see from the side.
- The motherboard and its many components were very easy to remove and inspect. It looked as though it was meant to be easily accessed and added to. It was also interesting to see how different each computer was. The one we were taking apart was older than the one next to us and many things were different about the motherboard and its components. Our pieces were much larger, and there were more of them. Just comparing the processor, ours was much larger than the one in the newer computer next to ours. Additionally, our computer was much harder to take apart. It had many screws and sharp metal pieces. The newer computers looked much easier to take apart, and had less pieces. The pieces that were there were held with plastic and pins, so it seemed like the newer computers needed less force to take apart.
The Connected Pieces
- Sound Card