1. The System Unit What is the system unit? p. 4.04 Fig. 4-1 Next  Case that contains electronic components of the computer used to process data  Sometimes called the chassis system unit

2. The System Unit What are common components inside the system unit? p. 4.03 Fig. 4-2 Next  Processor  Memory  Adapter cards  Sound card  Modem card  Video card  Network card  Ports  Drive bays  Power supply power supply ports drive bays processor memory sound card video card modem card network card

3. The System Unit What is the motherboard? p. 4.04 Fig. 4-3 Next  Main circuit board in system unit  Contains adapter cards, processor chips, and memory chips  Also called system board processor chip adapter cards memory chips memory slots motherboard Expansion slots for adapter cards

4. The System Unit What is a chip? p. 4.04 Fig. 4-4 Next dual inline packages (DIP) holds memory chips pin grid array (PGA) package holds processor chips  Small piece of semi-conducting material on which integrated circuits are etched  Integrated circuits contain many microscopic pathways capable of carrying electrical current  Chips are packaged so they can be attached to a circuit board

5. Processor Control Unit Arithmetic Logic Unit (ALU) Central Processing Unit What is the central processing unit (CPU)? p. 4.05 Fig. 4-5 Next Input Devices Storage Devices Output Devices  Interprets and carries out basic instructions that operate a computer Memory DataInformation Instruction Data Information Control Unit  Control unit directs and coordinates operations in computer  Arithmetic logic unit (ALU) performs arithmetic, comparison, and logical operations  Also called the processor

6. Central Processing Unit What is a machine cycle? p. 4.06 Fig. 4-6 Next  Four operations of the CPU comprise a machine cycle

7. Central Processing Unit What is pipelining? p. 4.07 Fig. 4-7 Next  CPU begins fetching second instruction before completing machine cycle for first instruction  Results in faster processing

8. Stores location from where instruction was fetched Central Processing Unit What is a register? Stores instruction while it is being decoded p. 4.07 Next Stores data while ALU computes it Stores results of calculation  Temporary high-speed storage area that holds data and instructions

9. Central Processing Unit What is the system clock? p. 4.07 Click to view Web Link, then click Clock Speed below Chapter 4 Next Each tick is a clock cycle Pace of system clock is clock speed Most clock speeds are in the gigahertz (GHz) range (1 GHz = one billion ticks of system clock per second) Processor speed can also be measured in millions of instructions per second (MIPS)  Controls timing of all computer operations  Generates regular electronic pulses, or ticks, that set operating pace of components of system unit

10. Central Processing Unit How do personal computer processors compare? p. 4.08 Next Comparison of Widely Used Personal Computer Processors NameDateClock IntroducedSpeed Itanium 220021 GH Z and up Xeon20011.4–2.4 GH Z Itanium2001733–800 MH Z Pentium 42000 1.4–2.53 GH Z Pentium III Xeon1999 500–900 MH Z Pentium III1999 400 MH Z –1.2 GH Z Celeron1998266 MH Z –1.8 GH Z Operon2003To come Athlon MP20021.53–1.6 GH Z Athlon XP20011.33–1.73 GH Z Athlon 1999 500 MH Z –1.4 GH Z ® ™ ® ® ® ™ ® ® ™ ™ ™ ™

11. Central Processing Unit Which processor should you select? p. 4.10 Next  The faster the processor, the more expensive the computer

12. Chip-for chip upgrade replace the chip Central Processing Unit What are the types of processor upgrades? p. 4.10 Next Piggyback upgrade stack new chip on top of old one Daughterboard upgrade chip is on adapter card that plugs into motherboard

13. Central Processing Unit What are heat sinks and heat pipes? p. 4.12 Fig. 4-11 Next  Heat sink—component with fins that cools processor heat sink fan heat sink  Heat pipe—smaller device for notebook computers

14. Central Processing Unit What is parallel processing? p. 4.12 Fig. 4-12 Next Control Processor Processor 1 Memory Processor 2 Memory Processor 3 Memory Processor 4 Memory Results combined  Using multiple processors simultaneously to execute a program faster  Requires special software to divide problem and bring results together

15. Data Representation How do computers represent data? p. 4.13 Fig. 4-13 Next  Recognize only two discrete states: on or off  Use a binary system to recognize two states  Use Number system with two unique digits: 0 and 1, called bits (short for binary digits)  Most computers are digital

16. Data Representation What is a byte? p. 4.13 Fig. 4-14 Next  Eight bits grouped together as a unit  Provides enough different combinations of 0s and 1s to represent 256 individual characters  Numbers  Uppercase and lowercase letters  Punctuation marks

17. Data Representation What are three popular coding systems to represent data? p. 4.14 Next  ASCII—American Standard Code for Information Interchange  EBCDIC—Extended Binary Coded Decimal Interchange Code  Unicode—coding scheme capable of representing all world’s languages ASCIISymbolEBCDIC 00110000011110000 00110001111110001 00110010211110010 00110011311110011

18. Data Representation How is a letter converted to binary form and back? p. 4.15 Fig. 4-16 Next Step 1. The user presses the capital letter D (shift+D key) on the keyboard. Step 2. An electronic signal for the capital letter D is sent to the system unit. Step 3. The signal for the capital letter D is converted to its ASCII binary code (01000100) and is stored in memory for processing. Step 4. After processing, the binary code for the capital letter D is converted to an image, and displayed on the output device.