09. Memory, Storage (RAM, Cache, HDD, ODD, SSD, Flashdrives)
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09. Memory, Storage (RAM, Cache, HDD, ODD, SSD, Flashdrives)

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RAM, Cache, HDD, ODD, SSD, Flashdrives - Storage, Memory
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Computer, Hardware, පරිගණක, දෘඩාංග, Information Technology, තොරතුරු තාක්ෂණය
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  • 1. Computer Memory/Storage
  • 2. Measuring Units  BIT: BInary digiT (0 or 1)  Word: Natural unit of data used by a particular processor design. The number of bits in a word (the word size, word width, or word length) is an important characteristic of any specific processor design or computer architecture. Majority of the registers in a processor are usually word sized. (32 bit, 64 bit)  Kilobit: 1000 bits  Byte: 8 bits  KiloByte (KB): 210 Bytes  Kibibyte (KiB): 210 Bytes  Binary_prefix: 1 KiB = 210 B, 1MiB = 220 B, 1GiB = 230 B (1 gibibyte) = (210 mebibytes) = (220 kibibytes) = (230 bytes) 2
  • 3. Memory/Storage Categories  Category 1  Main Memory  Primary Memory/Storage  Internal Memory/Storage  Category 2  Secondary Memory/Storage  Auxiliary Memory/Storage  External Memory/Storage 3
  • 4. Characteristics  Volatility  Volatile  Non-volatile  Mutability  Read/Write  Read Only  Accessibility  Random Access  Direct Access  Sequential Access 4
  • 5. Volatile Memory  Requires power to maintain the stored information  Retains the information as long as power supply is on, but when power supply is off or interrupted the stored memory is lost  RAM  2 main categories  DRAM (Dynamic RAM): RAM, Registers  SRAM (Static RAM): Cache Memory, Registers  Memory Refresh is needed in DRAM and not needed in SRAM 5
  • 6. Non-volatile Memory  Can retain stored information even when not powered  ROM: Read Only Memory  Flash Memory  F-RAM  Most Secondary Storage Devices 6
  • 7. ROM  Read Only Memory Types  Optical Storage ROM (CD/DVD/BD ROM)  Semiconductor based  PROM: Programmable Read-Only Memory  EPROM: Erasable Programmable Read-Only Memory  EEPROM: Electrically Erasable Programmable Read-Only Memory o EAROM o Flash Memory 7
  • 8. Read/Write  HDD: Hard Disk Drives  Flash Drives  Re-Writable Optical Disks  SSD: Solid State Drives  Also RAM, Cache, Registers 8
  • 9. Read Only  Optical ROM (CD/DVD/BD ROM)  Semiconductor ROM http://en.wikipedia.org/wiki/Write_Once_Read_Many 9
  • 10. Random, Direct, Sequential Access  Random Access  Main Memory: RAM, Cache  Direct Access  Disks: HDD, Optical Disks  Sequential Access  Tapes: Magnetic Tapes (Cassette, VHS) 10
  • 11. Random vs. Sequential Access 11
  • 12. SDRAM - DIMM Generally in practical world, the term RAM mostly used regarding SDRAM/DIMM 12
  • 13. SDRAM  Synchronous DRAM  SDRAM is DRAM synchronized with the system bus while classic DRAM has an asynchronous interface 13
  • 14. DIMM  Dual In-line Memory Module  Series of DRAM integrated circuits  Successor of SIMM (Single IMM) 14
  • 15. Generations of SDRAM  SDR SDRAM: Single Data Rate SDRAM  DDR SDRAM: Double Data Rate SDRAM  DDR  DDR2  DDR3  DDR4 15
  • 16. DDR SDRAM Comparison DDR SDRAM Standard Bus clock (MHz) Transfer Rate (MT/s) Voltage (V) DIMM pins DDR(1) 100–200  200–400  2.5/2.6 184 DDR2 200–533  400–1066 1.8 240 DDR3 400–1066 800–2133 1.5 240 16
  • 17. DDR SDRAM Comparison 17
  • 18. Key Values of a DIMM 18  Generation (DDR2, DDR3)  Frequency/Data Rate (1333, 1600)  Capacity (2048 MB, 4 GB)
  • 19. Determine Generation/Data Rate  Some vendors do not print DRAM generation/frequency in labels directly  But most of them label module names which contains generation and bandwidth info  PCX-#  The Generation is X and the memory bandwidth is #  Memory Frequency and Data Rate can be determined using memory bandwidth  Examples  PC-3200 : DDR, 400 (3200/8=400)  PC2-6400: DDR2, 800 (6400/8=800)  PC3-12800: DDR3, 1600 (12800/8=1600) 19
  • 20. DIMM Vendors  Kingston  G.Skill  Toshiba  Samsung  Hynix  Corsair + many more (Not in Particular Order :) 20
  • 21. HDD Hard Disk Drives
  • 22. HDD: Hard Disk Drives  Direct Access Storage  Used for storing and retrieving digital information using rapidly rotating discs (platters) coated with magnetic material  Records data by magnetizing a thin film of ferromagnetic material on a disk  Consists of a spindle that holds flat circular disks, also called platters, which hold the recorded data  Platters in most consumer HDDs spin in the range of 5,400 rpm to 7,200 rpm  Information is written to and read from a platter as it rotates past devices called read-and-write heads that operate very close over the magnetic surface  Modern drives there is one head for each magnetic platter surface on the spindle 22
  • 23. HDD Capacity  Capacity measured by GB, TB  Vendors and Operating System uses 2 different methods to measure HDD capacity  Vendors use 1000 metric (SI) method (1KB=1000B) as a marketing trick and OS uses 1024 method (1KB=1024B) which is similar to binary prefix method  Therefore labeled size is different from the size we see from the size shown by the OS  Examples:  1TB : 931.32 GB  500GB : 465.66 GB (Actual Usable Size may also differ…) 23
  • 24. HDD Performance  RPM: Rotations Per Second  5400, 7200, 10000… etc.  Latency: The delay for the rotation of the disk to bring the required disk sector  Seek Time: The time for the actuator arm to reach the desired disk track  Access Time = Seek Time + Latency  Data Transfer Rate 24
  • 25. HDD Interface  http://en.wikipedia.org/wiki/Hard_disk_drive_i nterface  (P)ATA: Parallel ATA  SATA: Serial ATA 25
  • 26. SATA vs. PATA 26
  • 27. External HDD  External/Portable HDDs typically connect through USB or eSATA ports  Most External HDDs now use USB 3.0 interface  External HDDs are Slower, compared to Internal HDDs  Certain Portable HDDs have extra features such as special Encryption methods, Security Options, Shock Protection, etc… 27
  • 28. HDD Related Terms  ECC: Error Correcting Code  http://en.wikipedia.org/wiki/Forward_error_correction  S.M.A.R.T: Self-Monitoring, Analysis and Reporting Technology  http://en.wikipedia.org/wiki/S.M.A.R.T  Disk Buffer/Cache: Embedded memory acting as a buffer between the computer and the physical hard disk platter. Usually 8 to 128 MiB  RAID: Redundant Array of Independent Disks  http://en.wikipedia.org/wiki/RAID 28
  • 29. HDD Vendors 29  Samsung  Seagate  Western Digital  Hitachi  Quantum  Toshiba + many more [Not in Particular Order :]
  • 30. Optical Storage CD, DVD, BD
  • 31. Optical Storage Devices  Optical storage is a storage method in which data is written and read with a optical beam (laser)  ODD: Optical Disk Drive  Typically used for archival or backup purposes  Slower than HDDs  Less vulnerable to environmental conditions  Data stream is placed in a spiral path. The data begins at the innermost track and works its way out toward the edge of the disc  Data is read by a laser beam always  Data is also written/burned by laser beams, but in industrial mass produced discs, the data is placed on the disc by a stamping machine 31
  • 32. Optical Disc Generations  First-generation  CD  Second-generation  DVD  Third-generation  BD  Fourth-generation  HVD 32
  • 33. CD: Compact Disc  Developed by: Philips, Sony  Read mechanism: 780 nm wavelength (infrared and red edge) semiconductor laser (Speed 1200 Kib/s = 1 , Generally 52 )  CD-R (Compact Disc-Recordable)  CD-RW (Compact Disc-ReWritable)  Capacity: ~ 700 MiB 33
  • 34. CD: Compact Disc 34
  • 35. DVD  Developed by: Philips, Sony, Toshiba, and Panasonic in 1995  Read mechanism: 650 nm laser, (Speed 10.5 Mbit/s = 1 , Generally 16 )  Recordable DVDs: DVD-R and DVD+R  Re-Writable DVDs: DVD-RW, DVD+RW, and DVD-RAM  Capacity: ~ 4.7 GiB  DVD was an acronym (initialism) for the unofficial Digital Video Disk. Later the Backronym Digital Versatile Disc was introduced to express that DVD goes beyond video (Data, Software, Audio). However it was not universally accepted and a 1999 report decreed that DVD was "simply three letters" and stood for "nothing".  Today, usage varies and there is no universal agreement. Digital Versatile Disc has gained wide acceptance 35
  • 36. DVD 36
  • 37. BD: Blu-ray Disc  Designed to supersede DVD  BD is 120 mm in diameter and 1.2 mm thick, the same size as DVD and CD  Developed by: Blu-ray Disc Association  Read mechanism: 405 nm diode laser. (Speed 36 Mbit/s = 1 , Generally 2 )  Capacity: ~ 25 GB  BD-ROM (read-only) - for pre-recorded content  BD-R (recordable) - for PC data storage  BD-RE (rewritable) - for HDTV recording  BD-RW (rewritable) - for PC data storage  Blu-ray 3D, BD-XL, Printable Blu-ray 37
  • 38. BD: Blu-ray Disc 38
  • 39. Optical Staroge Read-Write 39 http://www.howstuffworks.com/blu-ray2.htm http://www.cd-info.com/blu-ray/
  • 40. HVD: Holographic Versatile Disc  The Holographic Versatile Disc (HVD) is an optical disc technology developed between April 2004 and mid-2008  Can store up to several terabytes of data on an optical disc 10 cm or 12 cm in diameter  Media type: Ultra-high density optical disc  Capacity: ~ 6 TB 40
  • 41. HVD: Holographic Versatile Disc 41
  • 42. Flash Drives
  • 43. Flash Drive Types 43  Generic  Solid-State Drives  USB Flash Drives and Memory Cards  Specific ● CompactFlash (CF) ● Multimedia Card (MMC) ● Memory Stick (MS) ● Secure Digital (SD, SDHC, SDXC)
  • 44. SSD Solid-State Drives
  • 45. SSD: Solid State Drives  A data storage device using integrated circuit assemblies as memory to store data persistently  Unlike HDDs, SSDs have no moving mechanical components  SSHD  Hybrid drives or solid state hybrid drives (SSHD) combine the features of SSDs and HDDs in the same unit, containing a large hard disk drive and an SSD cache to improve performance of frequently accessed data 45
  • 46. SSD vs HDD  SSD (Compared to HDD)…  High Cost  High Speed  Low Access Time  Low (No) Noise  Less susceptible to physical shock and magnetic fields  Less Power Consumption and Less Heat Generation  Smaller in Physical Size  Smaller in Capacity https://duckduckgo.com/?q=SSD+vs+HDD https://www.google.com/search?q=SSD+vs+HDD 46
  • 47. USB Flash Drive Pen Drive Jump Drive Thumb Drive
  • 48. USB Flash Drives  AKA: Pen Drive, Jump Drive, Thumb Drive  Uses a Flash Memory Chip  Has a USB Connector, Mostly USB 2.0 or 3.0  Usually very small in physical size and come in different shapes 48
  • 49. USB Flash Drives 49
  • 50. Memory Cards 50  Used by Mobile Phones, Digital Cameras, Music players , etc.  Memory Cards use a Flash Memory Chip  Memory Card Types  CompactFlash (CF)  Multimedia Card (MMC)  Memory Stick (MS)  Secure Digital (SD, SDHC, SDXC) (More)
  • 51. SD Card: Secure Digital Card  Most mobile devices uses SD cards now  SD specification (Capacity)  SD – SDSC (SD Standard Capacity)  SDHC (SD High Capacity): Up to 32 GB  SDXC (SD eXtended Capacity): Up to 2 TB  Physical Size  Standard: SD  Mini: miniSD  Micro: microSD 51
  • 52. SD, miniSD, microSD Comparison 52
  • 53. Card Readers  Memory Card readers are used to read/write singe or multiple types of Cards (CF, MMC, MS, SD)  USB and PCI Card Readers are available  Most Notebook Computers and some desktop PCs Contain Internal Card Readers  USB microSD card readers much similar to a Pen Drive 53
  • 54. Card Readers 54
  • 55. Online Storage
  • 56. Online Storage  http://en.wikipedia.org/wiki/Online_file_storage  http://en.wikipedia.org/wiki/Cloud_storage  Google Drive:  https://drive.google.com  SkyDrive  https://skydrive.live.com  DropBox  https://www.dropbox.com  SugarSync  https://www.sugarsync.com  Amazon Cloud Drive  http://www.amazon.com/gp/feature.html?ie=UTF8&docId=1000828861 56
  • 57. Thank You! :) Ayubowan!