1. 1 Copyright © 2003 Prentice Hall, IncSlides created by Bob Koziel

2. 2 Copyright © 2003 Prentice Hall, Inc Chapter 2 Inside the System Unit COMPUTERS IN YOUR FUTURE 2004 COMPUTERS IN YOUR FUTURE 2004 by Bryan Pfaffenberger and Bill Daley Chapter 2 Inside the System Unit What You Will Learn NEXT SLIDE Description of the data computers transfer or store Components found inside the system unit Components found on the motherboard How the CPU processes data Characteristics of a microprocessor’s performance Types of memory Purpose and types of expansion buses Differences between analog and digital electrical impulses

3. 3 Copyright © 2003 Prentice Hall, Inc ON 01 OR = 1 bit 10000011000011 OR = 1 Byte OFF 00 NEXT SLIDE Describing Hardware Performance Hardware performance refers to the amount of data a computer can store and how fast it can process the data. Bit (Binary digit)– On or off state of electric current; considered the basic unit of information; represented by 1s and 0s (binary numbers). Byte– Eight bits grouped together to represent a character (an alphabetical letter, a number, or a punctuation symbol); 256 different combinations.

4. 4 Copyright © 2003 Prentice Hall, Inc 8 bits = 1 Byte 1024 Bytes = 1 Kilobyte (KB) 1,048,576 Bytes = 1 Megabyte (MB) 1,043,741,824 Bytes = 1 Gigabyte (GB) 1,099,511,627,776 Bytes = 1 Terabyte (TB) NEXT SLIDE Millions, Billions, and More Kilobyte, megabyte, gigabyte, and terabyte are terms that describe large units of data. Data storage is measured using these terms. Example: 20 GB hard drive

5. 5 Copyright © 2003 Prentice Hall, Inc 1000 bits = 1 kilobit (kb) 1,000,000 bits = 1 megabit (mb) 1,000,000,000 bits = 1 gigabit (gb) NEXT SLIDE Millions, Billions, and More Kilobits, megabits, and gigabits are terms that describe units of data. Used for measuring data transfer rate (bits per second). Example: 56 kbps

6. 6 Copyright © 2003 Prentice Hall, Inc NEXT SLIDE The System Unit The system unit is boxlike case that houses the computer’s main hardware components. Space taken up on the desk is called a footprint. Form factor refers to how the internal components are mounted in the unit.

7. 7 Copyright © 2003 Prentice Hall, Inc Desktop Notebook Personal Digital Assistant NEXT SLIDE Types of System Units

8. 8 Copyright © 2003 Prentice Hall, Inc I NEXT SLIDE Inside the System Unit Motherboard (mainboard)– Large printed circuit board with thousands of electrical circuits Power supply– Transforms alternating current (AC) from wall outlets to direct current (DC) needed by the computer Cooling fan– Keeps the system unit cool Internal Speaker– Used for beeps when error is encountered Drive bays– Housing for the computer’s hard drive, floppy drive, and CD-ROM / DVD-ROM drives

9. 9 Copyright © 2003 Prentice Hall, Inc Microprocessor Printer Port Video Port PCI Slots Memory Slots AGP Slot Chipset Click on terms to view larger images and information Keyboard / Mouse Ports The Motherboard

10. 10 Copyright © 2003 Prentice Hall, Inc I NEXT SLIDE Components of the CPU Control unit– Coordinates and controls all parts of the computer system. Arithmetic-Logic unit– Performs arithmetic or logical operations. Registers– Store the most frequently used instructions and data.

11. 11 Copyright © 2003 Prentice Hall, Inc CPUs at Work I NEXT SLIDE Control Unit– Manages four basic operations (fetch, decode, execute, and write-back).  The machine cycle or processing cycle: Instruction Cycle  Fetch- Gets next program instruction from the computer’s memory.  Decode- Figures out what the program is telling the computer to do. Execution Cycle  Execute- Performs the requested action.  Write-back (Store)- Writes (stores) the results to a register or to memory. Arithmetic-Logic Unit (ALU)– Performs basic arithmetic or logic operations.  Adds, subtracts, multiplies, and divides  Compares data to determine which one is larger or smaller.

12. 12 Copyright © 2003 Prentice Hall, Inc Control unit ALU Memory Click to animate. Click one time only NEXT SLIDE The Processing Cycle

13. 13 Copyright © 2003 Prentice Hall, Inc NEXT SLIDE Microprocessor Performance Data bus width– The number of pathways within the CPU that transfer data (8, 16, 32, or 64) Word size– The maximum number of bits of data that the CPU can process at a time (8 bits, 16 bits, 32 bits, or 64 bits) Operations per cycle (clock speed)– The number of clock cycles per second measured in Megahertz (MHz) or Gigahertz (GHz).  Superscalar– Carrying out more than one instruction per clock cycle.  Pipelining– Feeding a new instruction into the CPU at every step of the processing cycle.

14. 14 Copyright © 2003 Prentice Hall, Inc Parallel Processing Parallel processing involves using more than one CPU to improve performance. Complex instruction set computer (CISC)– A chip that includes special-purpose circuits that carry out instructions at high speeds. Reduced instruction set computer (RISC)– A chip with a bare-bones instruction set that results in a faster processing speed than CISC chips. NEXT SLIDE

15. 15 Copyright © 2003 Prentice Hall, Inc Intel Advanced Micro Devices (AMD) Cyrix Motorola (Apple) Pentium IV Pentium MMX Pentium III NEXT SLIDE Popular CPUs (of days gone by)

16. 16 Copyright © 2003 Prentice Hall, Inc Memory is a term for a device that enables the computer to retain (store) information. RAMROM Flash NEXT SLIDE Memory

17. 17 Copyright © 2003 Prentice Hall, Inc DIMM SIMM NOTEBOOK DIMM RIMM NEXT SLIDE Memory Modules

18. 18 Copyright © 2003 Prentice Hall, Inc NEXT SLIDE Memory Categories Volatile memory– Contents of memory are erased when power supply is turned off. It is temporary storage.  RAM– Random access memory holds data in locations called memory addresses.  Cache memory– Memory that the processor uses to store frequently used instructions and data.  Virtual memory– The computer uses the hard disk as an extension of RAM. Nonvolatile memory– Contents of memory are not erased when power is turned off.  ROM– Read-only memory provides the instructions to start the computer.  Flash memory– Memory that can be rewritten.

19. 19 Copyright © 2003 Prentice Hall, Inc NEXT SLIDE Random Access Memory / RAM RAM is a type of volatile memory that stores information temporarily so that it’s available to the CPU.

20. 20 Copyright © 2003 Prentice Hall, Inc WEB KEYBOARD CPU RAM MONITOR CLICK TO BEGIN ANIMATION Copyright © 2003 Prentice Hall, Inc HOW RAM WORKS NEXT SLIDE

21. 21 Copyright © 2003 Prentice Hall, Inc Virtual memory involves:  Part of the hard disk is reserved as RAM.  When RAM modules become full, the CPU accesses the hard disk to store and retrieve data.  Slower than RAM. FULL NEXT SLIDE Virtual Memory

22. 22 Copyright © 2003 Prentice Hall, Inc BIOS and CMOS BIOS– Basic input/output system is stored in ROM.  Its instructions provide the boot sequence when starting the computer.  The boot sequence includes: POST– Power-on self-test checks memory and configures video and other hardware. Locating the disk drive with the boot sector which contains the operating system. CMOS– Complementary metal-oxide semiconductor is a type of memory which stores essential startup options.  It stores the amount of memory installed and tracks date and time.  It is volatile. NEXT SLIDE

23. 23 Copyright © 2003 Prentice Hall, Inc NEXT SLIDE Cache Memory Primary cache (Level 1 or L1)– Located within the CPU chip, it is the memory the microprocessor uses to store frequently used instructions and data. Secondary cache (Level 2 or L2; Backside Cache)– Located near the CPU, it is the memory between the CPU and RAM. It is faster than RAM.

24. 24 Copyright © 2003 Prentice Hall, Inc NEXT SLIDE Chipset A chipset is a collection of chips that work together. It provides circuitry to move data to and from the rest of the computer.

25. 25 Copyright © 2003 Prentice Hall, Inc Expansion slots Expansion card NEXT SLIDE Input/Output (I/O) Buses I/O buses are pathways that enable the CPU to communicate with input/output devices. Typically the buses contain slots, called expansion slots, in which expansion cards are inserted.

26. 26 Copyright © 2003 Prentice Hall, Inc Drive bays On/off switch Reset button Indicator lights FRONT BACK NEXT SLIDE Outside the System Unit Power switch– Is located on the back. It turns power on/off to the computer. Receptacles– Also called connectors or ports, are located on the back to plug in peripheral devices, keyboard, mouse, and monitor. Front panel– Contains drive bays, various buttons, and lights.

27. 27 Copyright © 2003 Prentice Hall, Inc Types of Ports PS/2 port (mouse port)– Special serial port to connect mouse.PS/2 port (keyboard port)– Special serial port to connect keyboard. Universal Serial Bus (USB)– Allows up to 127 devices to be connected at a time. Serial port– Data flows in a series of pulses, one after another one bit at a time; slow data transfer rate. Parallel port– Data flows through eight wires allowing the transfer of eight bits of data simultaneously; faster than serial ports. VGA connector– A 15 pin connector used for monitorsGame port– A connector for high speed access for graphics- intensive interaction. Sound card connectors– Also called jacks, they accept stereo mini-plugs. Microphone, line-in, line-out, and speaker connectors are used. Click on a port below to view information about it. Click again to remove the text. NEXT SLIDE

28. 28 Copyright © 2003 Prentice Hall, Inc SERIALPARALLEL NEXT SLIDE The difference between serial and parallel ports

29. 29 Copyright © 2003 Prentice Hall, Inc Analog Digital OFFON NEXT SLIDE How a Computer Represents Data Computers represent data through electronic signals or impulses. Two types of signals:  Analog– Continuous waveform. Examples: talking and computerized gas pumps  Digital– On/off electrical states (bit). Examples: light switches and transistors

30. 30 Copyright © 2003 Prentice Hall, Inc 01000011 00000011 = 4 = A NEXT SLIDE Character Codes Numerical data, that computers use; translated into characters readable by humans.  American Standard Code for Information Interchange (ASCII)– Eight bits; used by minicomputers and personal computers  Extended Binary Coded Decimal Interchange Code (EBCDIC)– Eight bits; used by mainframe computers  Unicode– Uses 16 bits; over 65,000 combinations

31. 31 Copyright © 2003 Prentice Hall, Inc NEXT SLIDE Chapter 2 Summary 1.The basic unit of information is the bit. 2.Large units of data are kilobyte (KB), megabyte (MB), gigabyte (GB), and terabyte (TB). 3.The motherboard is a circuit board that provides receptacles for chips and input/output buses. 4.The central processing unit (CPU) contains the control unit (CU) and the arithmetic-logic unit (ALU). It manages the four basic operations (fetch, decode, execute, and write-back). 5.The CPU’s performance is measured by the data bus width, operations per second, speed, and cache memory. 6.Random access memory (RAM) is the computer’s main memory. It is volatile. 1.The basic unit of information is the bit. 2.Large units of data are kilobyte (KB), megabyte (MB), gigabyte (GB), and terabyte (TB). 3.The motherboard is a circuit board that provides receptacles for chips and input/output buses. 4.The central processing unit (CPU) contains the control unit (CU) and the arithmetic-logic unit (ALU). It manages the four basic operations (fetch, decode, execute, and write-back). 5.The CPU’s performance is measured by the data bus width, operations per second, speed, and cache memory. 6.Random access memory (RAM) is the computer’s main memory. It is volatile.

32. 32 Copyright © 2003 Prentice Hall, Inc NEXT SLIDE Chapter 2 Summary cont. 7.There are various types of RAM. They include dynamic RAM (DRAM), synchronous DRAM (SDRAM), Rambus DRAM (RDRAM), and double data rate (DDR)SDRAM. 8.Peripheral devices connect to the computer on the outside of the case. 9.Computers have ports such as serial ports, parallel ports, SCSI ports, USB ports, FireWire ports, and IrDA ports to connect input/output devices. 10.Analog computers measure and digital computers count. 7.There are various types of RAM. They include dynamic RAM (DRAM), synchronous DRAM (SDRAM), Rambus DRAM (RDRAM), and double data rate (DDR)SDRAM. 8.Peripheral devices connect to the computer on the outside of the case. 9.Computers have ports such as serial ports, parallel ports, SCSI ports, USB ports, FireWire ports, and IrDA ports to connect input/output devices. 10.Analog computers measure and digital computers count.

33. 33 Copyright © 2003 Prentice Hall, Inc THE END

34. 34 Copyright © 2003 Prentice Hall, Inc Microprocessor (CPU)- Central processing unit interprets and carries out instructions given by software. CPU CPU socket RETURN

35. 35 Copyright © 2003 Prentice Hall, Inc Memory- Enables the computer to retain information. RAM slots RETURN RAM module

36. 36 Copyright © 2003 Prentice Hall, Inc Chipset- A collection of chips that provide the switching circuitry needed to move data. RETURN

37. 37 Copyright © 2003 Prentice Hall, Inc Input/Output buses- Pathways that allow the microprocessor to communicate with input and output devices. RETURN