103a-ag PC Lab

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103a-xx Open-it Up! Lab

The main parts inside a computer, and how they work:

  • the processor The processor retrieves instructions from addresses in the memory. It can also store data in the memory, and move data around. Additionally, its ALU unit can perform mathematical functions. It consists of a single chip with a fairly small amount of memory, but controls all of the functioning of the computer. This chip contains transistors assembled into logic gates, which function as the logical operators "and", "or", and "not.". The speed of the processor is measured in megahertz (or in more recent processors, gigahertz), and is known as the "clock speed". Intel manufactured the first single-chip processor, the 4004, and Intel processors remain the most prevalent type of processor in home computers, with the most recent model being the Pentium 4 [1].
  • the memory The memory consists of a series of memory circuits, each of which stores one bit, which can read as either 0 or 1. Eight of these bits comprise a byte, which is the size of a single character in ascii. Modern computers often have between 256 megabytes (or 256 million bytes) and a gigabyte (1 billion bytes) of random access memory, or RAM. As its name indicates, addresses in the RAM can be accessed in any order, and do not need to be read in a specific sequence. All programs and processes, including the computer's operating system, that are running at a given time are stored on the RAM as long as they are open. The processor can then retrieve instructions as needed. [2]
  • the CD-ROM The reflective surface of a CD is actually a series of microscopic raised areas and indentations, or "pits", which are read by the computer as bits of binary data. As the disc spins, a laser is shone onto it, and is reflected onto an electronic optical receptor. The reflection changes depending on whether the laser is hitting a raised area or pit, and is interpreted accordingly. [3]
  • the hard drive The hard drive resembles a CD, but while it does store data on tracks, it does so in a different manner. Instead of pits and bits, it has tiny magnetic areas that are polarized either north-south or south-north. These are both written and read as binary data by a read-write head, which floats just above the spinning disk. It can't touch the disk because the hard drive spins at up to 100 mph.
  • the power-supply The power supply converts the power coming into the computer, reduces the voltage as needed by each component, and distributes it. While standard electrical outlets provide 110 volts of AC power, the various components of the computer typically use 3.3 or 5 volts (digital circuits) or 12 volts (drives, fans). [4]
  • the motherboard The motherboard is the hub of activity in the computer. It holds the processor, RAM, clock, and other components, as well as "daughterboards" such as graphics cards. The components of the motherboard are connected by buses, which are collections of wires with the same purpose.
  • the cables The computer cables convey bits of data between the components of the computer.
  • the battery The battery powers the "real-time clock chip", which keeps track of the passage of time and regulates the computer even when it is powered off [5].
  • the crystal The crystal keeps time, and regulates the processor's speed. It vibrates at a certain number of megahertz, which equates to how many millons of instructions per second the computer can process [6].

References

[1]Brain, Marshall. "How Microprocessors Work." (April 1, 2000). HowStuffWorks.com. [Online]. Available: <http://computer.howstuffworks.com/microprocessor.htm>

[2]Tyson, Jeff. "How Computer Memory Works." (23 August 2000). "HowStuffWorks.com". [Online]. Available: <http://computer.howstuffworks.com/computer-memory.htm>

[3]Brain, Marshall. "How CDs Work." (01 April 2000). HowStuffWorks.com. [Online]. Available: <http://electronics.howstuffworks.com/cd.htm>

[4]Brown, Gary. "How PC Power Supplies Work." (05 March 2001). HowStuffWorks.com. [Online]. Available: <http://computer.howstuffworks.com/power-supply.htm>

[5]Wilson, Tracy V., and Ryan Johnson. "How Motherboards Work." (20 July 2005). HowStuffWorks.com. [Online]. Available: <http://computer.howstuffworks.com/motherboard.htm>

[6]David Eck, The Most Complex Machine. Natick, MA: A K Peters, Ltd., 2000, p. 48

Lab report

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Talia Levy Dec. 22

Pictures

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  • We began to disassemble the computer by taking out the screws in the back. We then pressed the two buttons on either side of the chassis to open it.

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  • Greg helped us out.

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  • We removed the components from the computer. We took out the motherboard first, as it seemed to be connected to everything. As we took things out, we noticed that green plastic tabs seemed to indicate the method by which something could be removed.

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  • The computer components, laid out on the table.

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  • The processor, attached to a heat sink. Apparently, the processor gets very hot.

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  • 512 MB of RAM.

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  • The power supply.

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  • The hard drive.

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  • The CD drive.

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  • The motherboard.

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  • The fan.

One of the instructors who walked by our table remarked that our computer's chassis was poorly designed, and I am inclined to agree. He mentioned that better-designed cases housed their components such that when the chassis was opened, everything was on one side. I would be curious to see the inside of one of these computers, to determine whether it is less difficult to isolate components and determine what is connected to what.

103a-ag 03:19, 24 September 2008 (UTC)