103a-ac PC Lab
103a-ac Open-it Up! Lab
The main parts inside a computer, and how they work
Every computer needs a motherboard for is to work. The motherboard contains everything the computer needs in order to work. Motherboards today contain the processor, the memory, the chipset, which connects the processor to the rest of the computer, the battery, and countless other slots and ports. The motherboard transports bits from different parts of the board through a bus. The speed of the bus is measured in Megahertz (MHz) .
The Processor (Central Processing Unit)
The processor is probably the most expensive and one of the most important parts of a computer. The processor is one aspect of the motherboard, which controls most of the computer through multiple wires transporting bits to other hardware. The Central Processing Unit (CPU) executes a program that is stored in the computer's memory. Executing an instruction from memory requires turning certain wires on or off (or moving the ones and zeros around) according to the the pattern of the instruction . We are able to power these wires by the use of a switches known as transistors.
The amount of instructions a processor can execute in a second determines the processing speed. This speed given in Megahertz (MHz) or the 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 which vary in specifications. The most well known processors are the Intel processors. The first microprocessor in a home computer was the Intel 8080 . This was the first 8-bit computer in one chip, a remarkable feat in 1974. Since then, Intel has created faster and more powerful microprocessors, including the Intel Pentium line of processors that have 125 million or more transistors, far larger than the 6,000 the Intel 8080 had.
Memory is simply a temporary form of storage for a computer. Here, the computer's CPU can access the memory and retrieve any program data it may need, but first the data needs to come from a source. That source is usually the computer's hard drive or an input such as a keyboard . A computer's memory holds a large collection of bits, representing both the data and the programs currently available to the computer, encoded as patterns of bits .
What exactly is a bit? A bit is one-eighth of a byte or one byte is equivalent to 8 bits. A byte is the smallest amount of information found in a computer. If a computers CPU is 16 bits, it can hold 2 bytes. Familiar terms that have the suffix byte are kilobytes (a thousand), megabytes (a million), and gigabytes (a billion).
Once, the computer is turned on, many processes begin to happen. One of them is the start up of the operating system. The computer loads the operating system (OS) from the hard disk (permanent storage) to the Random Access memory, or RAM. This allows the CPU to have immediate access to the operating system through out the time the computer is on.
There are many types of memory found in a computer. Three that we mentioned in class were ROM, RAM, and cache memory. ROM stands for Read-Only memory, RAM is Random access memory and it is the computer's main memory . Memory can also be found in the processor. This is known as cache memory. This is very useful since the processor won't have to go out and fetch the data. The processor will work faster since it will retrieve all the info it thinks it will need and save it in it's own memory .
The Disk Drive
This is also known as the hard drive. This disk is magnetic. Because of the hard disk's magnetic nature information can easily be erased and rewritten . The information is stored in little circles known as tracks. The speed of the hard drive is 10,000 rotations per minute.
The read/write head never touches the surface of the disk, it is always floating over the surface. If the head did touch, the disk would melt whenever the disk reached it's maximum speed. The processor deposits bits to the hard disk. When the track is full, it simply goes on to the next track.
The CD-ROM drive reads the information from the popular medium for storing data, CDs. The drive is equipped with a laser and an optical lens system that reads the bumps and curves of the CD. These pits contain the bits of data found on the CD. The CD player's goal is to focus the lasers on the pits and bumps on the CD, so that the data could be read when the light is reflected from the pits to the ROM drive .
The power supply does exactly what the name implies. Through a collection of wires, it supplies electricity to the different parts of the computer, such as the CD drive. The power supply converts the alternative current (AC) from the electricity socket into direct current (DC), which is what the computer needs. The typical voltage that a computer needs vary from 3.3 volts to 5 volts to 12 volts. 3.3- and 5 volts are normally used to by digital circuits, while 12 volts are needed to run the motors in disk drives and fans .These days, you don't need much to start up a computer these days. 5 volts of electricity will do the trick.
This battery is found in the motherboard. It is primarily used to power the Real Time Clock (RTC) which keeps track of the computer's time.
This is also known as the jumpers . This connects various hardware parts of the computer to the motherboard. The cable transfers bits from the CPU to the different parts of the computer.
 David Eck, The Most Complex Machine: A Survey Of Computers And Computing, Natick, MA, AK Peters, pp. 14
 David Eck, The Most Complex Machine: A Survey Of Computers And Computing, Natick, MA, AK Peters, pp. 13
 David Eck, The Most Complex Machine: A Survey Of Computers And Computing, Natick, MA, AK Peters, pp. 69
What happened in the Lab
On September 22, 2008 I had the chance to take apart a Dell DHM computer in the McConnell Foyer.
It took me the whole 1 hour and 20 minute class time to take apart this Dell.
I worked alone on this project. I didn't mind, since it gave me the opportunity to take out every part of the computer. I did have the help of the various professors who passed through the foyer and our TA, Alex C. Cheng.
The first items I took out of the case was the hard disk and the CD drive. These two were relatively easy to take out. All I had to do was push the green tabs on the side and pull them out.
After taking out the CD drive and the disk drive, I still had most of the computer to go.
I took out the 2 memory modules
Then the whole mother board! I explore that later in the class, but first I went for the other big computer parts.
During this part of the lab I managed to identify and take out these parts and more!
- Power supply
- USB port
At this stage of the lab, I managed to take a closer look at the motherboard. Everything just looked confusing, but I took looking at the motherboard one step at a time.
First, I tried to locate the processor. It was under a hood, but eventually I opened that out and took out the processor. After that I looked for the battery and anything else that could be taken out from the board.
This lab was a great learning experience. I got to see first hand what was in a computer. I had a great time deconstructing the parts of the computer. It's still miraculous how much a little chip could do, but now that little chip (and everything around it) is a little less mysterious.