The System Unit: Processing and Memory

1. The System Unit:Processing and Memory Chapter 2

2. Inside the “box”

3. Inside the System Unit • System unit: The main case of a computer • Holds the main hardware for a computer • Main Circuit board (Motherboard) • Storage devices • Power supply • Cooling fans • CPU • Memory • Expansion Cards • Other components such as CD/DVD drives

4. Inside the System Unit

5. The Motherboard • Circuit board: • A thin board containing computer chips and other electronic components • Computer chip: A very small pieces of silicon or other semi-conducting material onto which integrated circuits are embedded • Motherboard or system board: The main circuit board inside the system unit • All devices must connect to the motherboard • External devices (monitors, keyboards, mice, printers) typically connect by plugging into a port exposed through the exterior of the system unit • Wireless devices connect through a transceiver or wireless networking technology (like Bluetooth)

6. The CPU • Central processing unit (CPU): • Does the vast majority of processing for a computer • Also called a processor/microprocessor • Dual-core CPU: Contains the processing components (cores) of two separate processors on a single CPU • Quad-core CPU: Contains 4 cores

7. Memory • Memory refers to chip based storage • RAM (random access memory): Computer’s main memory • Temporary memory (volatile) • Can be expanded • ROM (read only memory): chips located on the motherboard into which data or programs have been permanently stored • Permanent (Non-volatile) • Registers: High-speed memory built into the CPU and used by the CPU • Cache memory: special group of very fast memory chips located in or close to the CPU • Level 1 is fastest, then Level 2, then Level 3 • More cache memory typically means faster processing

8. How Data Travels • Bus: An electronic path over which data can travel • Bus width: The number of wires in the bus over which data can travel • Bus speed: measured in MHz –how fast the CPU connects to chips • Bus width and speed determine the throughput (or bandwidth) of the bus • The amount of data that can be transferred by the bus in a given time period • Universal Serial Bus (USB) • FireWire/IEEE 1394 bus

9. Its all about “speed” and “timing” • Computer has 2 clocks to keep things synchronized to perform at the best possible speed: • CPU has its clock speed: • Measured in megahertz (MHz) or gigahertz (GHz) • Higher CPU clock speed = more instructions processed per second • System clock: Timing mechanism that synchronizes all of the computer’s operations on the motherboard • Ticks like a metronome • Number of ticks (cycles) per second = hertz (Hz) • 1MHz = 1 million ticks of the system clock per second

10. Fans, Heat Sinks, and Other Cooling Components • Heat: A continuing problem for CPU and computer manufacturers • Fans: Used on most personal computers • Heat sinks: Small components typically made out of aluminum with fins that help to dissipate heat • Water cooling systems: Cool the computer with liquid-filled tubes • Notebook cooling stands

11. Expansion Slots, Expansion Cards, and ExpressCards • Expansion slot: A location on the motherboard into which expansion cards are inserted • Expansion card: A circuit board used to add additional functionality or to attach a peripheral device • ExpressCard modules: Designed for notebook computer expansion

12. Ports and Connectors Port: A connector on the exterior of a computer’s system unit to which a device may be attached • SCSI • MIDI • IrDA • Flash memory card slots • Game • Audio • eSATA • Monitor (VGA, DVI, HDMI) • Network • Modem • USB • FireWire • Keyboard

13. Ports and Connectors

14. Making Computers Faster and Better Now and in the Future • Improving performance today • Add more memory • Perform system maintenance • Uninstall programs properly • Consider placing large files on external storage devices • Delete temporary files • Error check and defragment • Scan for viruses and spyware • Clean out dust once or twice a year • Buy a larger or second hard drive • Upgrade your Internet connection • Upgrade your video graphics card • Upgrade the CPU • Replace the Motherboard (faster busses)

15. The “language” of the computer

16. Data and Program Representation • Digital computers: • Circuit based • Circuits understand two states • off and on (0 and 1) • When the gate is open, its off (0) • When the gate is closed, its on (1) • Data is represented using 0’s and 1’s • Digital data representation: • Theprocess of representing data thatweenter in digital form so it can be understoodby a computer

17. The Binary Numbering System • Numbering system: A way of representing numbers • Decimal numbering system • Uses 10 symbols (0-9) • Binary numbering system • Uses only two symbols (1 and 0) to represent all possible numbers • Used by computers

18. How data translates into binary • Binary number patterns translate to our language (letters, symbols, colors, sound) • Based on 8 digit positions, each position having a certain value ------ ------ ------ ------ ------ ------ ------ ------ 128 64 32 16 8 4 2 1 • Letter “A” is mapped to a decimal number (65) using standard coding system Decimal “65” is converted to binary representation 0 1 0 0 0 0 0 1------ ------ ------ ------ ------ ------ ------ ------ 128 64 32 16 8 4 2 1

19. Digital Data Representation • Bit: The smallest unit of data that a binary computer can recognize (a single 1 or 0) • Byte = 8 bits • Byte terminology used to express the size of documents and other files, programs, etc. • Prefixes are often used to express larger quantities of bytes: kilobyte (KB), megabyte (MB), gigabyte (GB), terabyte (TB), etc.

20. Coding Systems for Text-Based Data • All Computers use a coding system • ASCII (American Standard Code for Information Interchange): coding system traditionally used with personal computers (8 bits per character) • EBCDIC (Extended Binary-Coded Decimal Interchange Code): developed by IBM, primarily for mainframe use. (16 bits per character) • Unicode: newer code (32 bits per character); universal coding standard designed to represent text-based data written in any ancient or modern language

21. Coding Systems for Other Types of Data • Graphics (still images such as photos or drawings) • Bitmapped images: A variety of bit depths are possible (4, 8, 24 bits) • More bits = more colors • Audio data: Must be in digital form in order to be stored on or processed by a computer • Often compressed when sent over the Internet • MP3 files • Video data: Displayed using a collection of frames, each frame contains a still image • Amount of data can be substantial, but can be compressed

22. Representing Programs: Machine Language • Machine language: Binary-based language for representing computer programs the computer can execute directly • Early programs were written in machine language. • Today’s programs still need to be translated into machine language in order to be understood by the computer • Most programs are written in other programming languages • Language translators are used to translate the programs into machine language

23. Storage Chapter 3

24. Storage System Characteristics Consist of a storage device and a storage medium Medium is insertedinto device to beused Storage devices are typically identified by letter

25. Storage System Characteristics Type: Magnetic (conventional hard drives, tape) Optical (CD/DVD’s) Solid State: Electrons (flash memory media: USB, camera cards ) Location: Local – internal or external Remote – somewhere else View: Logical file representation: The user’s view of the way data is stored Physical file representation: The actual physical way the data is stored on the storage media Storage Data can be stored randomly or sequentially

26. Data Retention Volatile Non-Volatile • Storage that lasts only while the power is on • RAM • CACHE • REGISTERS • Storage that lasts regardless of the power • HD • CD • DVD • USB • ROM

27. MAGNETIC STORAGE Hard Drives Tape

28. Hard Drives Magnetic SSD Hybrid • FEATURES • Use Random Access • Can be Internal/External • Can be Partitioned for recovery/dual boot • Disk Access time – seek/rotate/move

29. Magnetic Tape Systems Magnetic tape: Plastic tape with a magnetizable surface that stores data as a series of magnetic spots Primarily used for backup and archival purposes Sequential access only Low cost per megabyte Most tapes today are in the form of cartridge tapes Read from and written to via a tape drive

30. OPTICAL STORAGE CD’s DVD’s

31. Optical Discs Optical discs: store data optically (using laser beams) Types of discs: CD, DVD, or Blu-Ray Disc (BD) CD discs: hold 650 MB DVD discs: hold 4.7 GB (single-layer) – can be dual layer BD discs: hold 25 GB (single-layer) – can be dual layer Burning: Process of Recording data onto disc CD discs: Use infrared lasers DVD discs: Use red lasers BD discs: Use blue-violet lasers Can be internal or external drives External drives typically USB

32. Optical Discs

33. Read-Only Discs (-ROM) Read-only disc: end in –ROM Surface is molded or stamped to represent the data Can be read from, but not written to, by the user CD-ROM (compact disc read-only memory) DVD-ROM (digital versatile disc read-only memory) BD-ROM (Blu-Ray disc read-only memory) Normally come pre-recorded Software programs Clip art and other graphics Music Movies Games (UMD, Wii, Xbox, etc.)

34. Recordable Discs (-R or +R) Recordable disc: End in –R or +R Can be written to ONCE, but cannot be erased and reused Reflectivity of surface is changed by a laser (burned in) CD-R discs DVD-R/DVD+R discs BD-R Used for back up, sending large files to others, creating custom music CDs, storing home movies, etc.

35. Rewritable Discs (-RW or –RE) Rewritable disc: end in –RW or –RE Can be recorded on MANY TIMES - erased, and overwritten just like hard drives and USB’s CD-RW DVD-RW BD-RE Use phase-change technology where reflectivity of surface is changed by a laser and melted down for rewrite Heating and cooling process is used to change the reflectivity of the disc Can be changed back to erase the disc

36. SOLID STATE Uses CHIP-BASED ELECTRON STORAGE USB’s, Memory cards (SD, xD, CF, etc.)

37. Flash Memory Systems Chip-based storage medium No moving parts so more resistant to shock and vibration, require less power, makes no sound Uses SSD - Solid-state storage system Retain data – non-volatile Most often found in the form of: Flash memory cards USB flash drives Solid State or Hybrid hard drives Very small and so are very appropriate for use with digital cameras, digital music players, GPS devices, notebook computers, mobile devices, etc.

38. Flash Memory Systems

39. Smart Cards Smart card: Credit card-sized piece of plastic that contains some computer circuitry (processor, memory, and storage) Stores small amount of data (about 64 KB or less) Commonly used to store prepaid amounts of digital cash or personal information Smart card readers are built into or attached to a computer, keyboard, vending machine, or other device Some smart cards store biometric data Can be used in conjunction with encryption and other security technologies

40. Holographic Storage Holographic storage: Store data as holograms Emerging type of 3D storage technology Uses two blue laser beams to store data in three dimensions Reference beam Signal beam Potential initial applications for holographic data storage systems include: High-speed digital libraries Image processing for medical, video, and military purposes Any other applications in which data needs to be stored or retrieved quickly in large quantities but rarely changed

41. Holographic Storage

42. RAID RAID (redundant arrays of independent discs): Method of storing data on two or more hard drives that work together to do the job of a larger drive Usually involves recording redundant copies of stored data Helps to increase fault tolerance Different levels of RAID: RAID 0 = disk striping (spread files over two or more hard drives) RAID 1 = disk mirroring (duplicate copy) Other level use a combination or striping and mirroring

43. RAID

44. REMOTE STORAGE Cloud, NAS, SAN (could be magnetic, tape, electrons)

45. Other Types of Storage Systems Remote storage: Using a storage device not directly a part of the computer being used Cloud storage: Accessed via the Internet Via Web sites (Flickr, Facebook, Google Docs, etc.) Via online storage sites (Box.net, SkyDrive, etc.) Network attached storage (NAS) Storage device is connected directly to a network Storage Area Network (SAN) A whole network of hard drives, connected to a central computer To use a storage area network, you must have access to the central computer

46. Storage Systems for Large Computer Systems and Networks Storage server: Hardware device containing multiple high-speed hard drives Businesses have to store tremendous amounts of data Business data Employee andcustomer data E-discovery data

47. Input and Output Chapter 4

48. Learning Objectives Inputs –get data INTO the computer Describe the characteristics and purpose of a computer input devices Outputs – get data OUT of the computer Describe the characteristics and purpose of a computer output devices

49. Input: Keyboards Keyboard: An input device used to enter characters at the location marked by the insertion point or cursor Can be wired or wireless Built in or slide-out keyboard Pen or touch input (on-screen keyboard) Voice input Most computers today are designed to be used with a keyboard Typically contains: Standard alphanumeric keys Numeric keypad Function keys Delete and Backspace keys Control and Alternate keys Arrow directional keys and special keys

50. Input: Pointing Devices Pointing devices: Used to select and manipulate objects Used to input data Used to issue commands to the computer Common types of pointing devices: Mouse Optical or laser mice track with light 3D mice Pen/stylus/digital pen Signature capture Touch screen