1. Computer Architecture
How Does a Computer Work?
Chapter 6

2. Student Learning Outcomes
Explain the basic components (inside the box) of a personal computer and their related functions.
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System Unit
System unit is the case or box in which the motherboard and storage units are housed
p Fig. 6-1
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6.1 The Big Picture
Input
Data
Process
Data
Output
Information
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The System Unit
Motherboard is the large circuit board inside your system unit that holds the CPU, memory, and other essential electronic components
CAN YOU NAME THE PARTS?
An excellent exercise is to point at the red lines in this diagram and randomly ask students to identify the part/component.
By explaining the concept of the motherboard to students, it makes it easier for them to grasp. Ask your computing services department for an “old” board to take to class, and while you are identifying these components to students from the slide, the students can be passing around the real board. Most computing services departments are very glad to help out with this step, and many will gladly provide you with other components.
SimNet Concepts Support CD:
“The Motherboard” and “Inside the Computer”
p Fig. 6.3
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6. System Unit Terminology
Connector - plug used to connect a device to a computer
Port – Place through which information and instructions flow to your computer system
CPU – Chip that carries out instructions it receives from the software
RAM – Temporary memory that holds software instructions and information for the CPU
Again – by having a system to demonstrate these components with you are helping students grasp the concepts. The “seeing is believing” aspect of teaching this material makes it easier to lecture on, and easier for students who are not that versed in this area to understand and appreciate the material.
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7. System Unit Terminology
Expansion Card – Circuit board that is inserted into an expansion slot
Expansion Bus – highway system that moves information coming from & going to devices outside the motherboard
Expansion Slot – socket on the motherboard into which an expansion card is inserted
Again, bring some components to class greatly enhances this part of your lecture. Expansion cards such as video, fax/modem, sound cards etc. are fairly easy to get from your computing services department and make excellent props in your presentation.
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8. 6.2 Representing Information Inside a Computer
Binary digit (bit) has two states - 0 or 1
By combining bits into groups of 8, we can represent letters, symbols, and numbers, like the word "cool" (below)
A group of 8 bits represents one natural language character and is called a byte
By combining bits into groups of 8, we can make 256 (28) different patterns, and that’s enough patterns to represent the basis set of symbols we use in English and English-like alphabets.
Since this 8-bit group has enough unique patterns for what we need, it has become the standard over time.
A group of 8 bits that represents one natural language character is called a byte. And each byte has a unique pattern of 1’s and 0’s. That is, each of the 8 bits in a byte can be a 1 or a 0.
For example, if you were to type the word “COOL” on the keyboard, it would change into four bytes - one for each character - that would look like the following so it could be stored in RAM: C O L
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9. ASCII, EBCIDIC, and Unicode
ASCII —American Standard Code for Information Interchange
Used on personal computers; eight-bit coding system; 256 different patterns
EBCDIC —Extended Binary Coded Decimal Interchange Code
Used by IBM mainframes; eight-bit coding system; 256 different patterns
Unicode —coding scheme capable of representing many languages
Usable on many computers; 16-bit coding system; approximately 65,000 patterns
SimNet Concepts Support CD: “Data Representation Using Binary Codes”
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10. ASCII & EBCDIC Binary Representations
YOUR CHARACTERS
ASCII
EBCDIC
(space) ! # $
& 1 2 3 4 5 6 7 8 9
ASCII and EBCDIC are different ways of representing natural language characters in binary.
As a fun (but maybe tedious ) exercise, use the chart in your text book to put together a series of short words, using binary code. This will give the students an idea of the difficulty faced by programmers in the early years of programming. Students will learn about machine language later in the text.
p Fig. 6.7
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11. 6.3 CPU, RAM, and Machine Cycles
Central processing unit (CPU or microprocessor or processor). Chip that carries out instructions it receives from your software
Random access memory (RAM) Temporary memory that holds software instructions and information for the CPU
Machine cycle (CPU cycle or clock cycle) consists of retrieving, decoding, and executing the instruction, and returning the result to RAM
CPU – Central Processing Unit
All computer components must be connected in some way to the CPU.
Motherboard provides the base for these connections.
We can “never” have enough RAM, and we are constantly looking at getting a faster machine.
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12. Central Processing Unit
Chip that carries out instructions it receives
from your software
Role of the CPU is analogous to the role of
your brain – keeps everything functioning
as it’s supposed to
Once again, old chips are fairly easy to obtain, and passing a few around in class is a good idea. Explain to students that many recycle programs exist for old parts, and many of these parts actually end up being turned into jewelry….. imagine wearing a CPU in you ear – they will be a little heavy.
SimNet Concepts Support CD: “The CPU”
p Fig. 6.3
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13. Random Access Memory (RAM)
Work being
created
OS Instructions
RAM Holds
Application
Software
instructions
Keyboard
Strokes & Mouse
Movements
Ensure that students thoroughly understand that the contents of RAM are temporary and volatile. Ask them to explain what this means.
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14. Machine Cycle (CPU Cycle)
4. Store the result
In RAM
Machine cycle consists of:
3. Execute the
instruction
2. Decode the
1. Retrieve an
instruction from RAM
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How a CPU Works
Ask students to explain the above diagram.
The text book uses a good example comparing CPU operations to that of making lasagna. Use this example as well.
p Fig. 6.9
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16. CPU Clock Each beat or tick of the clock is called a CPU
cycle/machine cycle
CPU speed is quoted in
Megahertz (MHz = 1 million
CPU cycles per second) or
Gigahertz (GHz= 1 billiion
CPU cycles per second).
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Classes of CPU’s
Intel and AMD are two major manufacturers of CPUs for consumer computers
CPU speed and power continue to get faster
Higher-performance CPUs have top speeds and are the most expensive
As an exercise ask students which one they have a personal preference for. In the Intel line you can select a true Intel chip or a Celeron chip – many buyers have a personal preference – or the purchase cost will influence which chip they will purchase.
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RAM Capacity
“Buy as much as you can afford”. For optimal performance purchase, more than the minimum specifications
512 MB is standard on new computers – i.e. 512 million bytes
RAM is very inexpensive. Put as much in your machine as you can afford to purchase, or add more memory modules as you can afford them. They are easy to install.
Once again, bring in an old motherboard and installing some RAM on it is a good demonstration for students. Show them that they cannot put in it wrong as the clips will only accept it being installed one way. Advise them NEVER to touch the gold colored pin part of RAM as human sweat and these connectors are not very friendly towards each other. Handle it with care, and avoid static at all cost.
SimNet Concepts Support CD: “Memory”
p Fig. 6.13
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19. RAM Capacity: How Much Do You Need?
Byte
Kilobyte (KB)
Megabytes (MB)
Gigabytes (GB)
Terabytes (TB)
Petabyte (PB)
Exabyte (EB)
= 8 bits
≈ 1 Thousand Bytes
≈ 1 Million Bytes
≈ 1 Billion Bytes
≈ 1 Trillion Bytes
≈ 1 quadrillion Bytes
≈ 1 quintillion Bytes
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20. RAM Capacity: How Much Do You Need?
Byte
Kilobyte (KB)
Megabytes (MB)
Gigabytes (GB)
Terabytes (TB)
Petabyte (PB)
Exabyte (EB)
= 8 bits
≈ 1000 ≈ ≈ ≈ ≈ ≈
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RAM and Virtual Memory
If your computer runs out of physical RAM space, it uses hard disk space as temporary RAM, which is called virtual memory
Virtual memory is slower than physical RAM because instructions temporarily stored on the hard disk must be moved into RAM as they are needed
Advise students that they should not rely on Virtual RAM as a replacement for physical RAM. RAM prices have dropped dramatically and basically is very affordable. Virtual RAM is no substitute for physical RAM.
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How Virtual RAM Works
p Fig. 6.14
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6.4 Making Connections
Ports are places in a computer system where external devices are plugged in, and through which information and instructions flow into the computer system
Connectors consist of cables that are used to join peripheral to the computer. Common types of connectors:
USB
Firewire
Serial
PS/2
Parallel
RJ-45
Bring in some of these connectors to class. Pass them around, and explain the difference between the different cables. You may also demonstrate that many devices which enable you to turn your serial mouse into a USB connecting mouse. They are only a couple of dollars. Many devices come with these “gadgets” included in the box.
p Fig. 6.15
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24. USB Connectors and Ports
USB (Universal serial bus) connector – is a plug-and-play interface between a computer and add-on device
With plug and play, a new device can be added to your computer without having to add an adapter card or even having to turn the computer off
USB is the newer type of connector. The newest version is USB Most of the new devices on the market today are USB.
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Firewire (IEEE 1394)
Firewire (IEEE1394) although different from USB, allows you to connect hot-swap, plug and play devices to your computer
Firewire used mostly for video camcorders and digital video disk (DVD) players
A popular implementation of IEEE 1394 is Sony’s I-LINK
Firewire is relatively new in the market place, and most commonly will be used with video camcorders and digital video disk players. If possible bring one these cables to class along with a device that uses it.
Also used for high-capacity music players.
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26. Serial Connectors and Ports
Serial means one event at a time. It is usually contrasted with parallel, meaning more than one event happening at a time
In the context of computer hardware and data transmission, serial connection, operation, and media usually indicate a simpler, slower operation and parallel indicates a faster operation
Ask students what the difference is between transmitting with a serial connector and a parallel connection. In their explanation, ask them which would be the safest buy longest method to use, and why it would be.
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27. Parallel Connectors and Ports
On a PC, the printer is usually attached through a parallel interface and cable so that it will print faster
Keyboard and mouse are one-way devices that only require a serial interface and line
Bring a parallel cord and a serial cord to class and show students the difference between the two.
SimNet Concepts Support CD: “Ports and Cables”
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Wireless Ports
Wireless is a term used to describe telecommunications in which electromagnetic waves (rather than some form of wire) carry the signal over part or all of the communications path
Ask students if they have ever used this type of technology. Is it available in their school? Do they have a laptop equipped with wireless ports. Does the instructor use a wireless pointing device to control the LCD projector when giving a lecture?
Asking students simple questions peeks their interest in the subject. After you have identified the “cool” things with using wireless ask them what is not “so cool” about wireless – the answer of course if the security issue.
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Wireless Ports – Cont.
Common examples of wireless equipment
Cellular phones
Global positioning systems
Cordless mouse
Wireless networks
Baby monitors
TV remote controls
Ask students if they have ever used this type of technology. Is it available in their school? Do they have a laptop equipped with wireless ports. Does the instructor use a wireless pointing device to control the LCD projector when giving a lecture?
Asking students simple questions peeks their interest in the subject. After you have identified the “cool” things with using wireless ask them what is not “so cool” about wireless – the answer of course if the security issue.
p Fig. 6.17
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Wireless Ports
IrDA (Infrared Data Association) port
Use infrared light to send and receive information
Bluetooth uses radio waves over distances of up to 30 feet
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31. IrDA (Infrared Data Association)
In this form of radio transmission, a focused ray of light in the infrared frequency spectrum, measured in terahertz, or trillions of hertz (cycles per second), is modulated and sent from a relatively short distance
IrDa communications is playing an important role in wireless data communication due to the popularity of laptop computers, personal digital assistants, digital cameras, mobile telephones, pagers, and other devices
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32. Examples for Using IrDA
Exchange business cards between handheld PCs
Send a document from a notebook computer to a printer
Coordinate schedules and telephone books between a desktop and notebook computer
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33. Examples for Using IrDA
Send faxes from a notebook computer to a distant fax machine through a public telephone
Beaming images from a digital camera into a computer
Interconnecting local area networks. Maximum effective distance is somewhat under 1.5 miles
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Bluetooth
Bluetooth is a computing and telecommunications industry specification that describes how mobile phones, computers, and PDAs can easily interconnect with each other and with home and business phones and computers using a short-range wireless connection
Bluetooth requires that a low-cost transceiver chip be included in each device
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35. Expansion Slots on the Motherboard
Most motherboards will have PCI and AGP slots and may also have an ISA slot. It is always beneficial to actually show students these components rather than just lecturing on them.
SimNet Concepts Support CD: “Expansion Cards and Slots”
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Buses
Data buses
Carries information in the form of bits around the motherboard
Two types: system and expansion
System bus
Electrical pathways which move information between RAM and CPU
The more bits that can travel together at one time, the faster the bus
Buses, or data buses, carry information in the form of bits around the motherboard in your computer.
The pathway that carries information between RAM and the CPU is part of the system bus.
The system bus consists of electrical pathways, which move information between basic components of the motherboard, including between RAM and the CPU.
The number of bits that can travel side by side at one time helps to determine the speed of the system bus.
Obviously, the more the bus can accommodate the faster the transfer of information, in the same way that multiple lanes on our traffic highways allow vehicles to reach their destinations more quickly.
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Expansion Bus
Moves information coming from and going to devices outside the motherboard
Types of expansion buses
ISA (industry standard architecture)
PCI (peripheral component interconnect)
AGP (accelerated graphics port)
Much of the elaborate circuitry that you can see on the top and bottom of the motherboard is part of the expansion bus, which is another system of pathways along which information moves.
The expansion bus forms the highway system that moves information coming from and going to devices outside the motherboard like your microphone or printer.
The ISA (industry standard architecture) bus is the oldest and slowest type of expansion bus. Newer motherboards have either one or none of these.
The PCI (peripheral component interconnect) bus is the most common in modern computers. The PCI bus moves information about 4 times faster than the ISA bus.
The AGP (accelerated graphics port) bus is dedicated to carrying complex graphics between the CPU and the AGP video card in the AGP slot on the motherboard. Unlike the ISA and PCI buses, AGP is usable only for carrying information to the monitor.
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PCI and AGP Buses
Explain to students the difference between PCI and AGP buses. Again taking some examples to class has a tremendous impact on the lecture you give, and the understanding that students will acquire.
p Fig. 6.19
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6.5 Notebook Computers
Notebook computer is smaller and power to run devices is limited
Biggest advantage is its portability
Electronic engineers work to reduce the power and size requirements of these computers
Bringing in some components from a notebook computer and sitting them beside the components from a desktop computer really makes a difference. Also, showing students the difference between the purchasing price for something like a hard drive or RAM for a laptop and purchasing those same components for a desktop machines also goes a long way in explaining the difference in the technology involved in producing these components. Replacement parts for a laptop are far more expensive than they are for a desk machine.
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40. Notebook Computers CPUs and RAM
Notebook hardware has special features
A mobile CPU is a special type of CPU for a notebook computer that changes speed, and therefore power consumption, in response to fluctuations in demand
The CPU fan comes on only when the CPU gets too hot
RAM for a notebook looks a little different from desktop RAM
Notebook RAM
Desktop RAM
p Fig & 6.20
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41. Notebook Computers – Expansion Cards and Slots
Devices are added to a notebook by sliding a PC card into the PC Card slot on the notebook, and connecting the device to the PC card
A PC Card is the expansion card used to add devices to notebook computers
p Fig. 6.21
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