1. Computer Architecture
Expected time: 40 min.

2. Outline Computer hardware {section 1.2} Memory
Central Processing Unit (CPU)
Input devices
Output devices
Network connections
Computer software {section 1.3}
System
Application
Every computer is organized roughly into five hardware parts.
Computer hardware refers to the physical devices that a computer is made of.
Most computer systems are made of similar hardware.
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3. Memory Memory is an essential component in any computer.
There are two types of memory:
main/primary memory, and
secondary memory (mass storage).
Memory stores data and programs.
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4. Main Memory Stores information being processed by the CPU.
There are two types of main memory, RAM & ROM.
RAM – Random Access Memory: the part of main memory that temporarily stores programs, data and results. It is volatile.
ROM – Read Only Memory: the part of main memory that permanently stores programs or data necessary for booting the computer.
When we talk about computer main memory in general we usually mean RAM.
Stores the program that is running/executing, as well as data.
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5. Secondary Memory Semi permanent data-storage capability Magnetic Tape
Floppy disk
Hard disk
Non-magnetic
CD-ROM or DVD
Memory stick/flash memory (USB drives)
Secondary memory usually has much more storage capacity than main memory.
USB stands for universal serial bus.
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6. Anatomy of Memory
The computer memory could be visualized as a sequence of storage locations called memory cells.
Each memory cell has a unique address, so as to be able to store and retrieve information in the memory.
Storing a value in memory destroys the previous contents.
Retrieving a value from memory copies the content to another storage area for processing.
Address
Contents
-27.2
354 1 H 2
ADD 7 3 . .
We use the word “cell” to refer to an arbitrary storage unit.
Memory cells could contain data or program instructions.
Notice that positions start in computer science and math from 0.
75.62
1024
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7. Anatomy of Memory (cont’d)
The smallest memory unit to represent a 1 or 0 is called bit (binary digit).
8 bits make a byte, which is the place required to store a single character.
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8. CPU “Brain” of the computer, where
decisions are made, computations are performed, and input/output requests are delegated.
CPU contains:
Arithmetic/Logic Unit - carries out all arithmetic and logical operations.
Control unit - decodes and executes instructions.
Registers - hold information and instructions for CPU to process.
Fundamental building block of a CPU is a switch.
Switches are made from ultrasmall transistors.
A register is a high speed memory located in the CPU.
Examples of CPUs:
The Pentium ® processor contains about three million transistors.
The Pentium Pro ® has about 5.5 million transistors.
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9. CPU (cont’d) CSCE106 CU (Control Unit)
Fetches and decodes instructions
Controls flow of information in and out of main memory
Controls operation of internal CPU components
Registers:
PC (program counter) - points to next instruction to be executed
IR (instruction register) - holds instruction currently being executed
ACC (accumulator) - holds results of ALU operation
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10. Input & Output Devices
Input devices are accessories that allow people to supply information to computers.
Common input devices:
Keyboard
Joystick
Scanner
Output devices are accessories that allow people to receive information from computers.
Common output devices:
Printer
Monitor
Speaker
Input devices allow a computer to receive information for processing
Output devices allow a computer to return the results of processing
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11. Basic Functional Components (1)
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12. Basic Functional Components (2)
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13. The Bus
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14. Computer Networks
Allow multiple computers to connect together to share resources and/or data.
LAN - Local area network
Organizational
WAN - Wide area network
Internet
Requires additional hardware
Modems
Ethernet interface
Network connection
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15. World Wide Web
Most popular feature on the Internet; introduced in 1989
A collection of interconnected documents that may be accessed from any computer
Navigation needs a Web browser
A program with a graphical user interface (GUI) that displays the text and graphics in a Web document and activates the hyperlinks to other documents.
Examples: Netscape and IE
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16. Computer Hardware Components
The figure shows how the computer hardware components interact in a computer when a program is executed; the arrows show the direction of information flow.
The program must be transferred from secondary memory to main memory before it can be executed.
Data must be supplied from some source; input device, a data file, or remotely from a network connection.
The data are stored in main memory where they can be accessed and manipulated by CPU.
Results are stored back in main memory.
Finally the results gets displayed to the user through an output device, stored, or sent to another computer via network.
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17. Computer Hardware Components
This figure shows some more modern input devices.
Source: Gaddis T. Starting Out With Games and Graphics in C++. Addison Wesley, 2010.
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18. Computer Software System software
Programs that support the execution and development of other programs.
Major types:
Operating systems
Utilities
Translation systems
Application software
Programs designed to perform specific tasks to the user.
Computers cannot think, although we are led to think otherwise.
Computers are devices for performing computations at incredible speeds (more than one billion instructions per second), and with great accuracy.
For a computer to accomplish anything useful, a computer must be provided with a list of instructions, i.e. a program.
A program is a list of instructions that a computer uses to manipulate data to perform a task.
Programs are written in special computer programming languages, such as C++.
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19. Operating System
Controls and manages the computing resources. It controls:
the interaction of system with the user, and
the hardware interactions.
Important services that an operating system (OS) provides are:
File system.
Commands that allow for manipulation of the file system.
Ability to perform input and output on a variety of devices.
Management of the running systems.
Part of the OS (required to boot the system) is usually stored on ROM, and the rest on hard drive.
Examples:
MSDOS ®, Windows ®, Unix ®
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20. Application Software
Application software is the software that has made using computers indispensable and popular.
Common application software:
Word processors
Desktop publishing programs
Spreadsheets
Presentation managers
Drawing programs
Next presentation/lecture will be about “Brief History of Computers & Computer Languages”.
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