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Relatively New RAM-RDRAM

Relatively New RAM-RDRAM. RDRAM---Rambus RAM It is a very fast different type of DRAM. Rambus is the company’s name. Intel has adopted this RAM for a while. The special RDRAM bus delivers address and control information using an asynchronous block-oriented protocol.

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Relatively New RAM-RDRAM

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  1. Relatively New RAM-RDRAM • RDRAM---Rambus RAM • It is a very fast different type of DRAM. • Rambus is the company’s name. Intel has adopted this RAM for a while. • The special RDRAM bus delivers address and control information using an asynchronous block-oriented protocol. • The bus can address up to 320 RDRAM chips and it rated at 1.6 GBps

  2. External Memory • 1. Magnetic disk---Floppy disk, hard disk • 2. Magnetic tape • 3. Optical Memory---CD, CD-R, CD-RW… • DVD, DVD-RW.

  3. Registers Cache Main Memory Magnetic disk Tape Optical disk

  4. Ir Iw MR sensor Write head shield S N S N S N S N 5-10 microns 0.1-0.2 microns 1-track width 1 bit Magnetic disk (HD)

  5. MR---Magnetoresistive Sensor • The MR material has an electrical resistance that depends on the direction of the magnetization of the medium moving under it. • By passing a current through the MR sensor, resistance changes are detected as voltage signals. • Main advantage: High frequency operation-----High Speed.

  6. HD-related terms • Track • Sector • Cylinder • Spindle speed RPM • Capacity • Track-to Track Seek Time • Average Seek Time

  7. Disk tracks are numbered from the outside edge, starting with zero.

  8. Hard disk platters are mounted on spindles. • Read/write heads are mounted on a comb that swings radially to read the disk.

  9. The rotating disk forms a logical cylinder beneath the read/write heads. • Data blocks are addressed by their cylinder, surface, and sector.

  10. HD --- cont…, • Average Rotational Delay • Maximum Transfer Rate • Bytes per Sector • Sector per Track • Track per Cylinder • Constant Angular Velocity

  11. Transfer Time • T = b/rN Where • T = transfer time • b = number of bytes to be transferred • N = number of bytes on a track • r = rotation speed, in revolution per second

  12. There are a number of electromechanical properties of hard disk drives that determine how fast its data can be accessed. • Seek time is the time that it takes for a disk arm to move into position over the desired cylinder. • Rotational delay is the time that it takes for the desired sector to move into position beneath the read/write head. • Seek time + rotational delay = access time.

  13. Transfer rate gives us the rate at which data can be read from the disk. • Average latency is a function of the rotational speed: • Mean Time To Failure (MTTF) is a statistically-determined value often calculated experimentally. • It usually doesn’t tell us much about the actual expected life of the disk. Design life is usually more realistic. Figure 7.11 in the text shows a sample disk specification.

  14. Floppy (flexible) disks are organized in the same way as hard disks, with concentric tracks that are divided into sectors. • Physical and logical limitations restrict floppies to much lower densities than hard disks. • A major logical limitation of the DOS/Windows floppy diskette is the organization of its file allocation table (FAT). • The FAT gives the status of each sector on the disk: Free, in use, damaged, reserved, etc.

  15. On a standard 1.44MB floppy, the FAT is limited to nine 512-byte sectors. • There are two copies of the FAT. • There are 18 sectors per track and 80 tracks on each surface of a floppy, for a total of 2880 sectors on the disk. So each FAT entry needs at least 14 bits (214=4096 < 213 = 2048). • FAT entries are actually 16 bits, and the organization is called FAT16.

  16. The disk directory associates logical file names with physical disk locations. • Directories contain a file name and the file’s first FAT entry. • If the file spans more than one sector (or cluster), the FAT contains a pointer to the next cluster (and FAT entry) for the file. • The FAT is read like a linked list until the <EOF> entry is found.

  17. A directory entry says that a file we want to read starts at sector 121 in the FAT fragment shown below. • Sectors 121, 124, 126, and 122 are read. After each sector is read, its FAT entry is to find the next sector occupied by the file. • At the FAT entry for sector 122, we find the end-of-file marker <EOF>.

  18. IDE---versus---SCSI • IDE---Integrated Drive Electronics • It has a limit of drive size of 528 MB • Due to the BIOS calling convention • 4 bits for head, 6 bits for the sector, 10 bits for the cylinder. The max. drive then has 16 heads, 63 sectors and 1024 cylinders • ----which lead to the 528MB • EIDE--- Extended IDE

  19. SCSI (Small Computer System Interface)Disks • Main features: • 1. Faster • 2. Allows more active drives at the same time 7 devices for SCSI and 15 devices for wide SCSI for a single SCSI Controller.

  20. RAID---Redundant Array of Inexpensive Disks(Independent Disks in other textbook) • Purpose---Increase both speed and reliability • Total 7 (0-6) levels in RAID scheme. • All the 7-levels share three common characteristics:

  21. 1. RAID is a set of physical disk drives viewed by the operating system as a single logical drive. • 2. Data are distributed across the physical drives of an array. • 3. Redundant disk capacity is used to store parity information, while guarantees data recoverability in case of a disk failure.

  22. These levels do not imply a hierarchical relationship • Level 0 doesn’t support the third characteristics. • Level 2 and 4 are not commercially offered and are not likely to achieve industry standard.

  23. RAID Level 0 (nonredundant) • Level 0 scheme Strip 0 Strip 1 Strip 2 Strip 3 Strip 4 Strip 5 Strip 6 Strip 7 Strip 8 Strip 9 Strip 10 Strip 11 Strip 12 Strip 13 Stri14 Strip 15

  24. Level 1---Mirrored • In this level, it added another same set of disks • main feature: • 1. Increased reliability. • 2. Same write speed. • 3. Double read speed can be realized. • 4. Easy to replace a bad disk.

  25. Strip 0 Array management software Strip1 Strip2 Strip 3 • . Strip 0 Strip 1 Strip 2 Strip 3 Strip 4 Strip 5 Strip 6 Strip 7 Strip 8 Strip 9 Strip 10 Strip 11 Strip 12 Strip 13 Stri14 Strip 15 Logical disk

  26. RAID…. • The main feature is the speed and reliability. • Due to the reason of cost, RAID is mainly used on larger systems.

  27. Serial and parallel ATA HD • Right now, the ATA hard drive landscape looks pretty good, and it's about to get even better. • Current ATA hard drives use the ATA/100 and ATA/133 specs, which are limited to transfer rates of 100 and 133MB/sec, respectively. • These drives use bulky 80-pin ribbon cables that clutter case interiors and interfere with internal air flow, but help is on the way. • The new Serial ATA standard promises transfer rates of up to 150MB/sec using thin, flexible cables might make some wonder how they got by with IDE ribbons at all.

  28. ATA -- Examples • Maximum Signaling Devices per Pins per • transfer rate voltage channel channel • (MB/sec) (volts) • ATA/133 • 133 5 2 40 • Serial ATA • 150 0.25 1 7

  29. The main difference between the two • Though Serial ATA offers a higher peak transfer rate performance than the fastest parallel ATA standard. • Serial ATA's signaling voltage is just 0.25V, one twentieth that of parallel ATA. • Such a low signaling voltage makes Serial ATA an attractive technology for mobile devices, but I can't imagine that the average desktop user will see much benefit from Serial ATA's lower power consumption. • Corporate IT types may appreciate Serial ATA's potential for lower power consumption for multi-drive RAID arrays that are constantly active.

  30. What is ATA? • ATA Short for Advanced Technology Attachment. • a disk drive implementation that integrates the controller on the disk drive itself. • There are several versions of ATA, all developed by the Small Form Factor (SFF) Committee:

  31. ATA • ATA: Known also as IDE, supports one or two hard drives, a 16-bit interface and PIO modes 0, 1 and 2. • ATA-2: Supports faster PIO modes (3 and 4) and multiword DMA modes (1 and 2). Also supports logical block addressing (LBA) and block transfers. ATA-2 is marketed as Fast ATA and Enhanced IDE (EIDE). • ATA-3: Minor revision to ATA-2.

  32. ATA • Ultra-ATA: Also called Ultra-DMA, ATA-33, and DMA-33, supports multiword DMA mode 3 running at 33 MBps. • ATA/66: A version of ATA proposed by Quantum Corporation, and supported by Intel, that doubles ATA's throughput to 66 MBps. • ATA/100: An updated version of ATA/66 that increases data transfer rates to 100 MBps. • ATA also is called Parallel ATA. Contrast with Serial ATA.

  33. Serial ATA • http://www.explosivelabs.com/articles/sata/

  34. CD 12mm • . 120mm in diameter 1.2mm thickness

  35. CD –ROMs Land Pit • Working principle: Label Protective acrylic Polycarbonate plastic Aluminum or other metals Laser beams

  36. Cross Section of CD-R Printed label Reflective gold layer Protective lacquer • . 1.2mm Polycarbonate Substrate Dye layer Reflective beam Transmit beam Dark spot burned by laser

  37. Information on the CD disks • Data are written in series form and are read in series fashion, too. • The disks have to rotate with a constant linear velocity for CD-music. • Single-speed CD-ROM drives operate at 75sectors/sec---153,600 bytes/sec in mode 1 and 175,200 bytes/sec in mode 2. • The difference between 1 and 2 is between music and video mode or data mode.

  38. Yellow Book Definition • The basic format of a CD-ROM consists of encoding every byte in a 14 –bit symbol. • A group of 42 consecutive symbols forms a 588-bit frame. (each frame holds 192 data bits and the remaining 396 bits are used for error correction and control) • 98 frames make 1 sector

  39. Similarity to HD • Both are external memories • Both disks rotate and have the head move above the disks • The heads float on the surface of the disks • Both can be made with high capacity

  40. The Differences Between the Two • HD is much faster than CD-ROM or CD-RW • CD-ROMs have much longer life if handled carefully.

  41. DVD • The capacity improvement are due to 3 factors: • 1. Smaller pits (0.4 microns versus 0.8 ) • 2. A tighter spiral (0.74 microns versus 1.6) • 3. A red laser at 0.65 microns versus 0.78 microns.

  42. Capacity of DVD • 1. Single-sided, single-layer (4.7GB). • 2. Single-sided, dual-layer (8.5GB). • 3. Double-sided, single-layer (9.4GB). • 4. Double-sided, dual-layer (17GB).

  43. Newer Blue-Laser DVD • There is a war between two new DVD standard right now. • One is SONY’s blue-ray system and the other is Toshiba’s HD-DVD system. • Nov 11, 2004 - Sharp Introduces Blu-ray Disc Recorder with Hard Drive/DVD

  44. Blue-Ray • Sharp today announced that they will introduce a new Blu-ray Disc recorder on the Japanese market in December. (11/11/2004) • The new BD-HD100, which features a built-in hard drive (160GB), can record and play back high-definition video (HDTV) without any loss in quality. • It comes equipped with the world's first twin BD/DVD tray that enables

  45. Blue-Ray • digital dubbing between the hard drive, DVDs, and Blu-ray Discs, including the ability to dub five DVDs (4.7GB) onto a single Blu-ray Disc (25GB). • The recorder also features an HDMI output jack, enabling users to enjoy full-digital high-definition video and high-fidelity audio with no signal deterioration by outputting recorded high-definition video (HDTV) to a compatible monitor for playback. • The BD-HD100 will begin selling in Japan next month for about 320,000 yen ($2,991).

  46. Blue-Ray • http://www.blu-ray.com/

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