Lec10. Memory and storage
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The document provides an overview of the system unit's components, including the motherboard, processor, memory types, and storage devices. It explains the differences between memory and storage, detailing various types of memory (RAM, ROM, cache) and storage media (hard disks, CDs, tapes). Additionally, it covers how data is accessed and managed in computing systems, emphasizing the importance of volatile and non-volatile storage.
Lec10. Memory and storage
- 1. The Components of the System Unit
- 2. What is the system unit? p. 180 Fig. 4-1 Next Case that contains electronic components of the computer used to process data Sometimes called the chassis
- 3. What are common components inside the system unit? p. 181 Fig. 4-2 Next 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 Processor
- 4. What is the motherboard? p. 182 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
- 5. The main circuit board of a microcomputer. The motherboard contains the connectors for attaching additional boards. Typically, the motherboard contains the CPU, BIOS, memory, mass storage interfaces, serial and parallel ports, expansion slots, and all the controllers required to control standard peripheral devices, such as the display screen, keyboard, and disk drive.
- 6. What is a chip? p. 182 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
- 7. A small piece of semiconducting material (usually silicon) on which an integrated circuit is embedded There are different types of chips. For example, CPU chips (also called microprocessors)
- 8. Computer sockets are the built-in interfaces on motherboards that accept various hardware components.
- 9. What are heat sinks and heat pipes? p. 190 Fig. 4-11 Next Heat sink—component that cools processor heat sink fan heat sink Heat pipe—smaller device for notebook computers
- 11. What is memory? p. 193 Fig. 4-17 Next Electronic components that store instructions, data, and results Consists of one or more chips on motherboard or other circuit board Each byte stored in unique location called an address, similar to seats on a passenger train Seat #2B4 Seat #2B3
- 12. 1.ROM (Read Only Memory) 2.RAM (Random Access Memory) 3.Cache 4.Flash memory
- 13. There is a type of memory that stores data without electrical current; it is the ROM (Read Only Memory) or is sometimes called non-volatile memory as it is not erased when the system is switched off.
- 14. PROM (Programmable Read Only Memory) EPROM (Erasable Programmable Read Only Memory) EEPROM (Electrically Erasable Read Only Memory .
- 15. Programmable read-only memory (PROM) is a blank ROM chip on which a programmer can write permanently, but once written cannot be changed or modified
- 16. But most ROM chips designed to be modified by users, use Erasable programmable read-only memory ( EPROM ) or electrically erasable programmable read-only memory ( EEPROM ).
- 17. An EPROM or erasable programmable read only memory, is a type of memory chip Once programmed, an EPROM can be erased
- 18. EEPROM (Electrically Erasable Programmable Read-Only Memory )is user-modifiable read- only memory (ROM) that can be erased and reprogrammed (written to) repeatedly
- 19. How is memory measured? p. 194 Fig. 4-18 Next Term Abbreviation Approximate Size Kilobyte KB or K 1 thousand bytes Megabyte MB 1 million bytes Gigabyte GB 1 billion bytes Terabyte TB 1 trillion bytes By number of bytes available for storage
- 20. Random Access Memory, a type of computer memory that can be accessed randomly; that is, any byte of memory can be accessed without touching the preceding bytes. RAM is the most common type of memory found in computers and other devices, such as printers.
- 21. What is random access memory (RAM)? p. 195 Next The more RAM a computer has, the faster it responds Also called main memory or primary storage Most RAM is volatile, it is lost when computer’s power is turned off Memory chips that can be read from and written to by processor
- 22. How do program instructions transfer in and out of RAM? p. 195 Fig. 4-19 Next Step 1. When you start the computer, certain operating system files are loaded into RAM from the hard disk. The operating system displays the user interface on the screen. Operating system instructions Web browser instructions Word processing program instructions Operating system interface Web browser window Word processing program window RAM RAM Web browser program instructions are removed from RAM Web browser window no longer is displayed on desktop Step 2. When you start a Web browser, the program’s instructions are loaded into RAM from the hard disk. The Web browser window is displayed on the screen. Step 3. When you start a word processing program, the program’s instructions are loaded into RAM from the hard disk. The word processing program, along with the Web Browser and certain operating system instructions are in RAM. The word processing program window is displayed on the screen. Step 4. When you quit a program, such as the Web browser, its program instructions are removed from RAM. The Web browser no longer is displayed on the screen.
- 23. Faster variations of DRAM are SDRAM and RDRAM Used for special applications such as cache Most common type Faster and more reliable than DRAM chips What are two basic types of RAM chips? p. 196 Next Static RAM (SRAM) Dynamic RAM (DRAM) Future: Magnetoresistive RAM (MRAM)
- 24. There are two different types of RAM: DRAM (Dynamic Random Access Memory) SRAM (Static Random Access Memory). DRAM needs to be refreshed thousands of times per second while SRAM does not need to be refreshed, which is what makes it faster than DRAM. Both types of RAM are volatile, meaning that they lose their contents when the power is turned off.
- 25. Where does memory chips reside? p. 196 Fig. 4-20 Next Memory slots on motherboard hold memory modules memory chip memory slot dual inline memory module
- 26. What is read-only memory (ROM)? p. 198 Next Memory chips that store permanent data and instructions Nonvolatile memory, it is not lost when computer’s power is turned off Three types: Firmware— Manufactured with permanently written data, instructions, or information EEPROM (electrically erasable programmable read-only memory)— Type of PROM containing microcode programmer can erase PROM (programmable read-only memory)— Blank ROM chip onto which a programmer can write permanently
- 27. What is cache? p. 198 Fig. 4-23 Next Helps speed computer processes by storing frequently used instructions and data Also called memory cache
- 28. Non volatile memory can be erased electronically and rewritten similar to EEPROM Most computers use it to hold up their startup instructions Also used in many mobiles , smart phones , digital cameras and PDA
- 29. The amount of time a processor takes to read the data, instructions and information from memory. A computer’s access time affects how fast the computer process data.
- 30. What is storage? p. 348 Fig. 7-1 Next Holds data, instructions, and information for future use Storage medium is physical material used for storage Also called secondary storage
- 31. What is capacity? p. 350 Next Kilobyte (KB) 1 thousand Megabyte (MB) 1 million Gigabyte (GB) 1 billion Terabyte (TB) 1 trillion Petabyte (PB) 1 quadrillion Number of bytes (characters) a storage medium can hold Exabyte (EB) 1 quintillion Zettabyte (ZB) 1 sextillion Yottabyte (YB) 1 septillion
- 32. Writing Process of transferring items from memory to storage media What is a storage device? p. 350 Next Reading Process of transferring items from storage media to memory Hardware that records and retrieves items to and from storage media Functions as source of input Creates output
- 33. Floppy Disk Small files to be transported Secondary Storage Primary Storage Hard Disk CDs and DVDs Miniature Storage Media Tape Items waiting to be interpreted and executed by the processor Operating system, application software, user data and information Software, backups, movies, music Digital pictures or small files to be transported Backups Memory (most RAM) Stores … What is access time? p. 350 Time it takes storage device to locate item on storage medium Next Time required to deliver item from memory to processor faster transfer rates slower transfer rates
- 34. 1.floppy disk 2.Zip disk 3.Hard disk 4.CDs and DVDs 5.Tape 6.PC Card 7.Miniature mobile storage
- 35. What is a floppy disk? p. 351 Fig. 7-5 Next Portable, inexpensive storage medium (also called diskette) Thin, circular, flexible film enclosed in 3.5” wide plastic shell shutter shell liner magnetic coating flexible thin film metal hub
- 36. What is a floppy disk drive? p. 352 Fig. 7-6 Next Floppy disk drive built into a desktop computer External floppy disk drive attaches to a computer with a cable Also called secondary storage One floppy drive, named drive A If two floppy drives, second designated as drive B Device that reads from and writes to floppy disk
- 37. p. 354 Next Never open the shutter and touch the disk’s surface How do you care for a floppy? Avoid exposure to heat and cold Avoid exposure to magnetic fields Avoid exposure to contaminants such as dust, smoke, or salt air Keep disks in a storage tray when not using them Proper care helps maximize disk’s life Floppy disk can last at least seven years
- 38. External Zip drive What is a Zip disk? p. 355 Fig. 7-11 Next Magnetic medium that stores 100 MB to 750 MB of data Zip disks require a Zip drivec—chigh capacity drive that reads from and writes on a Zip disk Used to back up and to transfer files Backup is duplicate of file, program, or disk in case original is lost c Zip disk
- 39. What is a hard disk? p. 355 Fig. 7-12 Next hard disk installed in system unit High-capacity storage Consists of several inflexible, circular platters that store items electronically Components enclosed in airtight, sealed case for protection
- 40. What are characteristics of a hard disk? p. 356 Fig. 7-13 Next Sample Hard Disk Characteristics Advertised capacity 120 GB Platters 3 Read/write heads 6 Cylinders 16,383 Bytes per second 512 Sectors per track 63 Sectors per drive 234,441,648 Revolutions per minute 7,200 Transfer rate 133 MB per second Access time 8.9 ms actual disk capacity
- 41. How does a hard disk work? p. 357 Fig. 7-14 Next Step 1. Circuit board controls movement of head actuator and a small motor. Step 2. Small motor spins platters while computer is running. Step 3. When software requests a disk access, read/write heads determine current or new location of data. Step 4. Head actuator positions read/write head arms over correct location on platters to read or write data.
- 42. What is a cylinder? p. 357 Fig. 7-15 Next Vertical section of track through all platters Single movement of read/write head arms accesses all platters in cylinder platter read/write head platter sides cylinder track sector
- 43. What is a head crash? p. 358 Fig. 7-16 Next clearance read/write head platter hair dust smoke Spinning creates cushion of air that floats read/write head above platter Occurs when read/write head touches platter surface A smoke particle, dust particle, or human hair could render drive unusable Clearance between head and platter is approximately two-millionths of an inch
- 44. hard disk Next What is a disk cache? p. 358 Fig. 7-17 Portion of memory that processor uses to store frequently accessed items second request for data—to hard disk disk cache first request for data—to disk cache processor
- 45. What are external hard disks and removable hard disks? p. 359 Fig. 7-18 Next External hard disk—freestanding hard disk that connects to system unit Removable hard disk—hard disk that you insert and remove from hard disk drive Used to back up or transfer files
- 46. What is an Internet hard drive? p. 360 Fig. 7-19 Next Others can be authorized to access your data Service on Web that provides storage for minimal monthly fee Files can be accessed from any computer with Web access Large files can be downloaded instantaneously
- 47. Push the same button to close the tray. What are CDs and DVDs? p. 361 Fig. 7-20 Next Most PCs include CD or DVD drive, most play audio CDs Flat, round, portable metal discs made of metal, plastic, and lacquer Can be read only or read/write Insert the disc, label side up. Push the button to slide out the tray.
- 48. How does a laser read data on a CD or DVD? p. 362 Fig. 7-21 Next laser diode laser diode prism prism light- sensing diode light- sensing diode 0 1 lens lens pit land disc label Step 1. Laser diode shines a light beam toward disc. Step 2. If light strikes a pit, it scatters. If light strikes a land, it is reflected back toward diode. Step 3. Reflected light is deflected to a light-sensing diode, which sends digital signals of 1 to computer. Absence of reflected light is read as digital signal of 0.
- 49. How is data stored on a CD or DVD? p. 362 Fig. 7-22 Next Typically stored in single track Track divided into evenly sized sectors that store items single track spirals to edge of disc disc sectors
- 50. What is a CD-ROM? p. 363 Fig. 7-24 Next Compact disc read- only memory Cannot erase or modify contents Typically holds 650 MB to 1 GB Commonly used to distribute multimedia and complex software
- 51. What are CD-Rs and CD-RWs? p. 366 Next Must have CD recorder or CD-R drive Cannot erase disc’s contents CD-R (compact disc-readable) —cdisc you can write on once CD-RW (compact disc-rewritable) —ceerasable disc you can write on multiple times Must have CD-RW software and CD-RW drive
- 52. What is tape? p. 370 Fig. 7-29 Next Magnetically coated plastic ribbon capable of storing large amounts of data at low cost Primarily used for backup
- 53. How is data stored on a tape? p. 370 Fig. 7-30 Next Sequential access Unlike direct access — used on floppy disks, Zip disks, hard disks, CDs, and DVDs — which can locate particular item immediately Reads and writes data consecutively, like music tape
- 54. What is a PC Card? p. 370 Figs. 7-31–7-32 Next PC Cards Category Thickness Use Type I 3.3 mm RAM, SRAM, flash memory Type II 5.0 mm Modem, LAN, SCSI, sound, TV turner, hard disk, or other storage Type III 10.5 mm Rotating storage such as a hard disk Adds capabilities to computer Credit-card-sized device commonly used in notebook computers
- 55. What is Miniature mobile storage media? p. 371 Fig. 7-33 Next Storage for small mobile devices
- 56. What are common types of miniature mobile storage media? p. 372 Next Smart Media xD Picture Card CompactFlash Secure Digital Memory Stick Microdrive
- 57. What is a card reader? p. 373 Fig. 7-35 Next Reads information stored on miniature mobile storage media Type of card determines type of card reader needed
- 58. What is a smart card? p. 373 Fig. 7-37 Next Stores data on microprocessor embedded in small card Input, process, output, and storage capabilities
- 59. What are microfilm and microfiche? p. 374 Fig. 7-38 Next Images recorded using computer output microfilm recorder Store microscopic images of documents on roll or sheet of film Microfilm — 100- to 215-foot roll of film Microfiche — small sheet of film, usually 4” 6”
- 60. A metaphor………. The file cabinet represents the computer's hard disk, which provides storage for all the files and information you need in your office. When you come in to work, you take out the files you need from storage and put them on your desk for easy access while you work on them. The desk is like memory in the computer: it holds the information and data you need to have handy while you're working.
- 61. The two terms are sometimes used interchangeably, so it is important to understand some key differences. 1. The term memory refers to the amount of RAM installed in the computer, whereas the term storage refers to the capacity of the computer’s hard disk.
- 62. 2. Both terms are used to refer to internal storage space on a computer. Memory, usually referred to as Random Access Memory (RAM), is the place where an application loads its data during processing, while a hard disk drive is usually the place where data is stored for long or short term retention.
- 63. 3. Memory dumps everything when you turn off your computer, in nature but the hard drive retains what is stored on it. 4. Memory is typically volatile Storage is typically non-volatile . 5. Memory is quite a lot faster than hard drive. 6.Computer storage is typically cheaper, slower while computer memory is expensive and faster
- 64. Storage Medium (floppy disks, Zip disks, hard disks, CDs) How does volatility compare? p. 350 Next Nonvolatile Storage medium is nonvolatile—contents retained when power is off Contents retained Contents available to user Memory (most RAM) (chips on motherboard) Screen Display ON OFF Volatile Display disappears Data and instructions available to user Display appears Data and instructions erased Memory is volatile—holds data and instructions temporarily