Computers Chapter 4 Inside the Computer © 2005 Prentice-Hall, Inc.Slide 2

Computers Inside the Computer Digital signals: Data is represented by a stream of bits. Bit – short for binary digit (either 0 or 1) 1 represents on 0 represents off © 2005 Prentice-Hall, Inc.Slide 6

Computers Inside the Computer The Language of Computers Encoding systems ASCII – American Standard Code for Information Interchange ANSI – American National Standards Institute UNICODE – capable of handling most printed languages © 2005 Prentice-Hall, Inc.Slide 7

Computers Inside the Computer Digital: The Language of Computers Byte – collection of bits that represent a character ASCII – 7 bits/byte ANSI – 8 bits/byte UNICODE – 16 bits/byte © 2005 Prentice-Hall, Inc.Slide 8

Computers Inside the Computer The PC System Unit Connected to the Motherboard: Processor Chipset Memory chips Expansion boards © 2005 Prentice-Hall, Inc.Slide 11

Computers Inside the Computer The PC System Unit Motherboard System bus – permits communication between components Device controllers – control peripheral devices © 2005 Prentice-Hall, Inc.Slide 12

Computers Inside the Computer The PC System Unit The Processor: Computer on a Chip Pentium 4 Celeron Xeon TM Itanium TM © 2005 Prentice-Hall, Inc.Slide 13

Computers Inside the Computer CPU Speed: GHz, MIPS, and FLOPS Gigahertz (GHz) – billions of clock cycles per second (Instructions) Megahertz (MHz) – millions of clock cycles per second (Instructions) © 2005 Prentice-Hall, Inc.Slide 39

Computers Inside the Computer CPU Speed: GHz, MIPS, and FLOPS MIPS – millions of instructions per second FLOPS – floating point operations per second; used to measure speed of supercomputers © 2005 Prentice-Hall, Inc.Slide 40

Computers Inside the Computer RAM: (Temporary Memory) High-speed holding area for data and programs Volatile memory – data is lost if electrical current is not maintained © 2005 Prentice-Hall, Inc.Slide 18

Computers Inside the Computer RAM: (Temporary Memory) DDR SDRAM – synchronous dynamic RAM SIMMs – single in-line memory modules DIMMs – dual in-line memory modules © 2005 Prentice-Hall, Inc.Slide 19

Computers Inside the Computer Cache Cache Memory – faster than RAM Housed on (L1) or near (L2) the CPU © 2005 Prentice-Hall, Inc.Slide 20

Computers Inside the Computer Other High-Speed Memories ROM (read-only memory) – contains instructions to the computer that the user cannot change PROM (programmable ROM) – user can store read-only programs and data © 2005 Prentice-Hall, Inc.Slide 21

Computers Inside the Computer Other High-Speed Memories Flash Memory Nonvolatile memory – does not lose data in a power outage Easily upgraded BIOS (Basic Input Output System) – stored in flash memory © 2005 Prentice-Hall, Inc.Slide 22

Computers Inside the Computer Memory Capacity MB (megabyte) – approximately 1 million bytes GB (gigabyte) – approximately 1 billion bytes TB (terabyte) – approximately 1 trillion bytes © 2005 Prentice-Hall, Inc.Slide 42

Computers Inside the Computer Memory Capacity KB (kilobytes) – approximately 1000 bytes Kb (kilobit) Mb (megabit) © 2005 Prentice-Hall, Inc.Slide 43

Computers Inside the Computer Buses and Ports PCI (peripheral component interconnect) local bus – allows for circuit boards to connect to the common system bus © 2005 Prentice-Hall, Inc.Slide 27

Computers Inside the Computer Buses and Ports Expansion slots – where expansion boards are installed Expansion boards or expansion cards – provide additional capabilities to the computer © 2005 Prentice-Hall, Inc.Slide 28

Computers Inside the Computer Buses and Ports AGP (accelerated graphics port) bus– speeds up high-resolution 3-D graphics © 2005 Prentice-Hall, Inc.Slide 29

Computers Inside the Computer Buses and Ports USB (universal serial bus) – used to connect peripheral devices to the PC USB hub – connects to the USB port and provides additional places to plug USB devices © 2005 Prentice-Hall, Inc.Slide 30

Computers Inside the Computer Buses and Ports Hot plug – USB devices can be attached or removed while the PC is running USB 2.0 – about 40 times faster than original USB © 2005 Prentice-Hall, Inc.Slide 31

Computers Inside the Computer Buses and Ports 1394 bus – similar to USB in speed FireWire – Apple terminology Supports hot plugging © 2005 Prentice-Hall, Inc.Slide 32

Computers Inside the Computer Buses and Ports SCSI (small computer system interface) or “scuzzy” bus – early alternative to expansion slots in PCs © 2005 Prentice-Hall, Inc.Slide 33

Computers Inside the Computer Legacy and Other PC Ports Serial port – data flows one bit at a time Parallel port – data flows several bits at a time IrDA port or infrared port – data sent by light waves © 2005 Prentice-Hall, Inc.Slide 34

Computers Inside the Computer Bus Speed Most buses operate at MHz Major block to efficiency in a PC © 2005 Prentice-Hall, Inc.Slide 41

Computers Inside the Computer PC Growth: Adding Capabilities Expansion Boards – placed in expansion slots Graphics adapter Sound Data/voice/fax modem Network interface card (NIC) SCSI interface card Video capture card © 2005 Prentice-Hall, Inc.Slide 35

Computers Inside the Computer PC Cards: PCMCIA Technology PCMCIA card or PC card Usually used on notebook computers Expand RAM NIC Hard-disk cards GPS (global positioning system) © 2005 Prentice-Hall, Inc.Slide 36

Computers Chapter 5 Storage Devices: (Permanente Storage) measured in Mega Bytes (MB), or Gaga Bytes (GB) –Hard Drive –Floppy Disc –CD-ROM –DVD-ROM –CD-R (Recordable) –CD-RW (Rewritable) –DVD-R, DVD+R –DVD-RW, DVD+RW –DVD+,-RW

Computers Inside the Computer Build Your Own PC Advantages Cheaper (for high-end systems) Meets your requirements Disadvantages No warranty on system No help desk © 2005 Prentice-Hall, Inc.Slide 37