HARDWARE TERMS

1. What are the four components of a computer system?

The four components of a computer system are hardware, software, data and people.

2. Identify what the letters IPOS stand for and describe the IPOS cycle.

The letters IPOS stand for input, process, output and storage. The IPOS cycle refers to the steps we go through each time we sit down at a personal computer. The words input, process, output and storage are used as verbs as well as nouns. As verbs, IPOS refers to actions we take while using a computer. As nouns, IPOS refers to computer components or categories of computer hardware we use to perform the actions of inputting, processing, outputting and storing data/information on a computer.
Input: We enter data into the computer with a device such as a keyboard or a mouse.
Process:Tthe central processing unit (CPU), along with RAM, changes the data into information.
Output: The results of the processing by the CPU are given back to the operator, usually either on the computer screen or sent to the printer.
Storage: The results of processing are saved for later use on a storage device such as a floppy or hard drive.

3. List five categories of computer hardware.

The five categories of computer hardware are processor (CPU), memory (RAM), input, output and storage devices.

4. What is the difference between input and output hardware? Provide two examples each of input and output devices.

Input hardware is used to enter data into a computer; output hardware is used to display or relay the results of a computer's processing. Examples of input hardware are a keyboard, a mouse, microphone, a hard drive or a modem. Examples of output hardware are a computer screen, speakers, a hard drive, a modem or a printer. As you can see, some devices can serve as both input and output devices.

5. What role does storage play in a computer system? List three different ways to store data.

The role of storage is to retain the results of processing for future use. As a computer changes data into information, the results of processing are held only in temporary memory. If a computer loses power for any reason, even for a tiny fraction of a second, the results of processing are lost. Once we save information to devices such as disk drives (hard and floppy), tape drives or a CD ROM, we can retain information even after the computer is turned off or loses power.

6. List two major distinctions between storage and memory.

Storage and memory both hold data and program instructions. They differ in how they do this. Two differences between storage and memory are:
Storage is long term, it doesn't need electricity to retain its contents; memory is temporary (volatile), it needs a constant supply of electricity or memory and all its contents disappear.
Accessing information in storage much takes longer than accessing the same information in memory (milliseconds vs. nanoseconds).
Two lesser differences between storage and memory are:
A computer typically has much more storage capacity than memory capacity (gigabytes vs. megabytes).
Storage is less expensive than memory (ten cents per megabyte vs. a dollar per megabyte).

7. What are the three functions performed by a CPU?

Although the term computer commonly refers to the combination of system case (box), keyboard, mouse and monitor, in actuality the computer is only one chip in the case. This chip is known as the central processing unit or CPU for short. A CPU is composed of two different parts, the Arithmetic Logic Unit (ALU) and the Control Unit.
For all the varied tasks that a computer can perform, the only tasks it is actually capable of are math, logic and control. By math we mean the CPU has the ability to add numbers. Logic refers to the CPU's ability to compare one quantity to another. Math and logic are carried out by the Arithmetic Logic Unit. By control, we mean the CPU's ability to move data into memory or to request that data or instructions be sent from memory to the CPU for processing. Control is handled by the Control Unit.

8. What is memory? Why does a CPU need memory?

Memory, also called Random Access Memory (RAM), is a CPU's temporary workspace used to hold program instructions, data and the results of processing. Without memory, a CPU would have no place to store data and program instructions. Program instructions and data are held in memory until the CPU needs them and the results of processing are then placed in memory once the computer finishes a task.
Memory's two most prominent features are its speed and volatility.
Speed: When data or program instructions are held in memory, they can be accessed in nanoseconds or billionths of a second. An access time of 60-80 nanoseconds is common.
Volatility: Memory must have a constant flow of electricity at a certain level in order for it to hold data or instructions. If power should be cut off momentarily or even dip below a certain level, memory and all its contents disappear.

9. List three ways a computer's power is affected by the amount of RAM the computer contains.

One measure of a computer's power is throughput or the amount of time it takes a computer to complete a task. Although the single most important factor that determines the power of a computer is the speed of its CPU, the amount of RAM installed in a computer plays a major role in how powerful a computer is. RAM affects a computer's power in three ways.

1. The amount of RAM installed in a computer controls how large a program and how many programs at one time the computer can work with.
2. The amount of RAM installed also determines how large the data files created with programs can be.
3. The more RAM installed in a computer, the less likely the computer is to use virtual memory. Virtual memory is a feature of some operating systems that allows a computer to use a portion of available hard drive space as if it were RAM. While the use of virtual memory allows a computer system to overcome some of the limitations imposed by a lack of physical RAM, it has a major draw back associated with it. Virtual memory is thousands of times slower than real RAM. A CPU can access data stored in RAM in 60-80 nanoseconds (billionths of a second). Accessing the same data on a hard drive takes 10-15 milliseconds (thousandths of a second). While using virtual memory will let you open larger programs or load bigger data files, working with programs and data is much faster if you have enough real RAM to hold all the programs and files you want to use.

10. What is a binary digit? How does a computer use binary digits?

A binary digit is either a one or a zero, the two numbers in a binary numbering system. Computers use binary digits as the building blocks of the programs and data stored on a computer. Just as bricks can be arranged in patterns to form patios, barbecues or walls, binary digits can be arranged in patterns to represent programs and data stored in a computer. The term bit is often used to refer to the ones and zeroes used by computers. The term bit is a contraction of the two words binary and digit.

11. What is a Byte? What is a byte composed of?

There are two meanings for the term byte.

1. A byte is an arrangement of eight bits (ones or zeroes) that represent a character such as the letter A or the number 1.
2. A byte is also the amount of memory or storage needed to hold one character.

12. How many bytes are there in a kilobyte, a megabyte, a gigabyte?

The terms kilobyte, megabyte and gigabyte refer to a collection of bytes stored in a computer. There are 1024 bytes in kilobyte, 1024 kilobytes in a megabyte and 1024 megabytes in a gigabyte. Although the above definitions are the accurate definitions, the terms kilobyte, megabyte and gigabyte also have a popular definition. A kilobyte is popularly referred to as 1000 bytes, a megabyte is popularly referred to as a million bytes and a gigabyte as billion bytes.

13. List the four types of data you might enter into a computer and give an example of each.

There are four types of data, numeric (numbers), textual (words), audio/visual, (sounds or pictures) and physical (measurements such as temperature or weight).

14. How do computers represent data or programs stored on a computer?

Everything stored on a computer, no matter how large or small the computer may be, is represented as a series of ones and zeroes arranged in unique patterns. Whether it is the data we enter with a keyboard or microphone or the programs we use to accomplish tasks such as sending email or adding a column of numbers, everything stored on a computer is represented as a series of ones and zeroes.

15. What is the purpose of the text code called ASCII?

The letters ASCII stand for American Standard Code for Information Interchange. ASCII uses unique arrangements of ones and zeroes to represent codes for controlling computer hardware, the letters of the alphabet, the digits zero through nine and punctuation marks. Since all personal computers understand ASCII, it is possible to transfer data saved in an ASCII format from a computer made by one company to another computer made by a different company. Because ASCII is something of a common language between computers and software programs, a file saved in ASCII format can be opened and read by almost any program, not just the one used to create it. Saving a file as text only is another way to refer to a file saved in ASCII format.

16. What two components does a computer use to transform data into information?

While the terms data and information are often used synonymously in everyday conversation, there is an important distinction between the two. Data are raw facts that have little value in and of themselves. Information is something we can use. One way to think of a computer is as a system for producing information. We enter data (raw facts) into the computer and the CPU, along with RAM, take that data and transform it into information. The hardware components that transform data into information are the CPU and RAM. Together, the CPU and RAM are often referred to as the system unit.

17. What is a motherboard? List three items you would find on a motherboard.

A motherboard is a piece of fiber glass containing the electrical circuitry that links the various computer components found inside the computer's case. Some of the components you'll find on a motherboard include the CPU, memory, the ROM chip or BIOS,the computer's power supply, the expansion bus and expansion cards.

18. What does it mean to boot a computer? What role does ROM play in booting a computer?

To boot a computer means to turn it on and have it go through the steps necessary for it to be able to accept and follow commands from an operator. When a computer is first turned on, control of the system is turned over to the ROM chip. ROM contains instructions that tell the computer how to proceed with the boot process. Before a computer is ready to accept commands, it has to determine what components are connected to the system and to verify that all components are working properly. Once this is accomplished, control of the computer is turned over to the operating system.

19. How does ROM differ from RAM? What does it mean to say that RAM is volatile?

The letters ROM stand for read only memory. ROM, also called BIOS, is a chip on the motherboard that holds start up instructions for a computer. Unlike RAM, these instructions are wired into the chip and so don't disappear when the computer is turned off. Also, the instructions held in ROM can't be changed easily or at all. Although some newer computers have the ability to let you use software to change the instructions found in ROM, for many computers, if you need a different set of ROM instructions, you must remove the chip and put in a new one. When a computer is first turned on, instructions found in ROM tell the computer how to proceed with the process of getting the computer ready to accept instructions from the user.
By contrast, RAM only exists as long as the computer has electricity. RAM is described as volatile because it disappears if the computer doesn't have enough electricity. Even if the power doesn't disappear completely, should electricity dip below a certain level, that would be enough for RAM and all its contents to disappear.

20. What is the role of a computer's system clock? What does a CPU's Megahertz rating tell you about that chip?

Inside every computer is a crystal that vibrates a fixed number of times per second. This crystal drives the computer's system clock. The system clock doesn't keep the time of day. Instead, the system clock is a timing device used to coordinate system events. Much like a band uses the beat of a drum to keep time, a computer turns transistors on and off to the beat of the system clock. With every tick of the clock, a transistor is turned on, a 1, or off, a 0. With every tick of the clock, a computer completes a cycle. The faster the clock ticks (the crystal vibrates), the faster a computer can process data. The term Megahertz means millions of cycles. Megahertz is a measure of how many millions of cycles per second a computer can complete. The higher the Megahertz rating, the faster and more powerful the computer is.
In addition to the system clock, computers have another clock called the real time clock. This clock is battery operated and keeps track of the date and time. Don't confuse the system clock with the real time clock.

21. What does the term bus refer to when used with computers? What are the two main computer buses?

A computer bus is a collection of circuits that carry electricity to and from the system components. Although computers have several different buses, the two main types of buses a computer has are data and address buses. A data bus carries data from system components to the CPU and back again. An address bus carries the address in memory where the CPU will find the data or program instructions needed for processing. Some examples of buses are ISA (Industry Standard Architecture), PCI (Peripheral Component Interconnect) and SCSI (Small Computer System Interface).

22. What is a cache? How does a cache improve a computer's throughput?

The fastest component of a computer system is usually the CPU. The CPU is so much faster than some of the other components such as the hard drive that it often sits idle waiting for the information it requested. The term cache refers to a temporary storage location for data. The purpose of a cache is to provide a CPU with the data it needs as quickly as possible. A cache does this by anticipating what data a CPU will need next and by placing needed data where the CPU can most quickly find it. The two main types of caches are disk and memory caches. A disk cache uses regular RAM while a memory cache uses a small amount of high speed RAM. Since a cache reduces the amount of time the CPU sits idle, the result is an increase in system throughput.

23. What is the difference between a RISC and a CISC CPU? What are two advantages provided by RISC over CISC?

Every CPU is designed to understand a limited number of instructions. The number of instructions a CPU understands is called its instruction set. One way to classify CPUs is by the number of instructions it understands, a complex set (CISC) or a reduced set (RISC). CISC chips understand a larger number of instructions than RISC chips. The ability to understand a larger set of instructions might seem like an advantage but it isn't. A RISC chip's instructions are smaller and simpler than those of a CISC chip. Because of this, generally speaking, a RISC chip will perform faster than a CISC chip operating at the same Megahertz. In addition to being faster, RISC chips are also less expensive to build.

24. What is symmetric multiprocessing? List two reasons parallel processing hasn't become more popular.

Symmetric multiprocessing, also referred to as parallel processing, is the use of more than one CPU in a computer. The use of two or even four CPUs in a personal computer is not uncommon today. Although using more than one CPU does make a computer faster, a computer with two CPUs won't be twice as fast as a computer with one CPU. So a computer with more than one CPU will be more expensive. Also, just because a computer has several CPUs doesn't mean its software can use more than one CPU at at time. It is much more difficult to write programs that can take advantage of multiple CPUs so there is not nearly as much multiprocessor aware software available.

25. Briefly describe the difference between an operating system and an application program.

Software may be divided into two main categories, system software and application software. Operating systems and applications are both sets of detailed instructions that tell a computer what to do and when and how to do it. The two types of programs contain different types of instructions. An operating system is the central control program on a personal computer. It is responsible for almost every activity that occurs while a computer is running. An application program lets a user complete a specific task such as printing a newsletter or sending email.