EOC Summary

1. What is a switch, and how does it work in a computer? Electrical switches are devices inside the computer that flip between two states: 1 or 0, on or off. Transistors are switches built out of layers of semiconductor material. Integrated circuits (or chips) are very small regions of semiconductor material that support a huge number of transistors. Integrated circuits enable computer designers to fit millions of transistors into a very small area.

2. What is the binary number system, and what role does it play in a computer system? The binary number system uses only two digits, 0 and 1. It is also referred to as the base 2 number system. It is used instead of the base 10 number system to manipulate the on/off switches that control the computer’s actions. Even with just two digits, the binary number system can still represent all the same values that a base 10 number system can. To provide a consistent means for representing letters and other characters, codes dictate how to represent characters in binary format. The ASCII code uses 8 bits (0s and 1s) to represent 255 characters. Unicode uses 16 bits of data for each character and can represent more than 65,000 character symbols.

3. What is inside the CPU, and how do these components operate? The CPU executes every instruction given to your computer. CPUs are differentiated by their processing power (how many transistors are on the microprocessor chip), how quickly the processor can work (called clock speed), and the amount of immediate access memory the CPU has (called cache memory). The CPU consists of two primary units: the control unit controls the switches inside the CPU, and the arithmetic logic unit (ALU) performs logical and arithmetic calculations.

4. How does a CPU process data and instructions? All CPUs must perform a series of similar general steps. These steps, referred to as a CPU machine cycle (or processing cycle), include: fetch (loading program and data binary code into the CPU), decode (translating the binary code into commands the CPU can understand), execute (carrying out the commands), and store (placing the results in special memory storage areas, called registers, before the process starts again).

5. What is cache memory? Cache memory consists of small blocks of memory, located directly on and next to the CPU chip, that hold recently or frequently used instructions or data that the CPU needs the most. The CPU can more quickly retrieve data and instructions from cache memory than from RAM.

6. What types of RAM are there? RAM is volatile storage, meaning that when you turn off your computer, the data stored there is erased. The cheapest and most basic type of RAM is DRAM (dynamic RAM). There are many types of RAM, including SDRAM, DDR SRAM, and DDR2s DRAM. All of these forms of RAM store data that the CPU can access quickly.

7. What is a bus, and how does it function in a computer system? A bus is an electrical wire in the computer’s circuitry through which data (or bits) travels between the computer’s various components. Local buses are on the motherboard and run between the CPU and the main system memory. Expansion buses expand the capabilities of your computer by allowing a range of different expansion cards to connect to the motherboard. The width of the bus (or the bus width) determines how many bits of data can be sent along a given bus at any one time.

8. How do manufacturers make CPUs so that they run faster? Pipelining is a technique that allows the CPU to work on more than one instruction (or stage of processing) at a time, thereby boosting CPU performance. Adual-processor design has two separate CPU chips installed on the same system. Multi-core systems are often used when intensive computational problems need to be solved. In parallel processing, computers in a large network each work on a portion of the same problem at the same time.