CSC231 2010 Amy PCDemo
On September 8th, 2010, a Dell PC computer was taken apart for viewing of the CSC231 class. Despite the inherent complexity of the machine, the class was able to identify the various parts. This was done in order to better understand the inner workings of the computer, giving us more information about what the assembly language will actually be doing in terms of hardware.
Amy Tayloe CSC 231 9/17/10
Deconstruction of a Computer
The main control point of the computer is the processor, in this case, an Intel chip, used for the basis of all computer interactions. These functions include:
- Fetching: getting commands from memory, as well as keeping track of where in the memory the processor is
- Decoding: translating the data in memory (consisting solely of ones and zeroes) into a meaningful set of commands
- Executing: going through the calculations instructed by memory
- Writing back: sending the output of the command either to permanent memory, RAM, a disk, the screen, etc. 
Due to the age of the computer, the chip in question was probably a 32-bit processor, although it is possible it was a more advanced 64-bit. The "bits" refer to the size of the address handleable by the CPU; in this case, it could access addresses up to 32 bits long, meaning that the total memory available to the chip would be 4 GB. 
In a computer, there are two ways of getting data: from primary memory stored in the computer, referred to as memory, or by secondary devices, referred to as storage. In the former, data can be kept in caches for easy access, and generally has a faster resolution time. Some data is kept in the processor itself, in the processor register, which has very fast access, but very limited space (usually a word). Commonly, basic commands are kept there. The processor cache, pictured to the right, holds commonly access commands. While slower than the register, it serves as a faster go-between for the CPU and the main memory, holding a greater amount of commonly-used commands. The memory itself holds the bulk of the data. Its slower access (due to its large address size) can slow down commands, but modern computers would not be able to function without its capacity for holding commands. 
While a lot of data can be held in main memory, data used less often can be kept on outside memory, such as CDs, zip disks, floppy disks, thumb drives, and the like. The drives used to access this memory still need to be connected to the CPU. These disks are removable, and because they can store much larger amounts of data than main memory, are known as storage. The access to this memory is hundreds of times slower than any of the RAM, due to the amount of time spent fetching and decoding. 
In order to transfer information to and from the CPU and main memory, tapes are used. There are two kinds: address tapes and data tapes. The first is often small, and transfers where to start reading via wires, one for each bit of the address. However, if the address is sent in chunks, space can be optimized. As such, tapes often have half as many wires as bits, and send the data one half at a time. The data tapes transfer the data to where its going. Since this data can get very large, it is sent in chunks of whatever size the bus is. 
The motherboard is used to hold basic commands and to translate for the computer, supporting things like keyboards, mice, disk drives, graphics cards, and similar. It is the most obvious part of the inner computer, although it does less of the actual work. 
Many portions of the CPU we removed were devices to connect the CPU with various input and output devices other than memory storage. Pictured below are the various parts.
Printer, Mouse, Keybord, USB Drives, Audio
Other Visual (including graphics chip)
Because of the amount of heat generated by the electricity moving through the computer, several cooling methods are employed. The largest (and loudest) is the fan, which sends cooler air through the computer and expels warmer air through vents. This is generally effective at cooling most parts of the computer, but tends to collect dust through its intake, which may slow the computer by interfering with the wires.
The second method of cooling is the heat sink, which uses low-specific heat metal or plastic to draw heat away from the components, and let the air carry some of the heat away. These increase the effectiveness of the fan, and also work to cool specific portions of the computer. For example, the processor chip has a heat sink of its own, due to the strain placed on the device.