1 / 18

Memory and Disc Drive hardware

Memory and Disc Drive hardware. Working Memory and Permanent Storage. Memory: RAM. “Random Access Memory” isn’t random at all, it’s just not serial memory RAM is the rapid, working, temporary memory of the computer (n.b. don’t confuse with HDD or Flash). Memory: RAM. Some RAM types:

lila-hendrix
Download Presentation

Memory and Disc Drive hardware

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Memory and Disc Drive hardware Working Memory and Permanent Storage

  2. Memory: RAM • “Random Access Memory” isn’t random at all, it’s just not serial memory • RAM is the rapid, working, temporary memory of the computer (n.b. don’t confuse with HDD or Flash)

  3. Memory: RAM • Some RAM types: • Low-power SDRAM • Double data-rate RAM (DDR RAM) • DDR2, DDR3, DDR4 (2013?) • You need a specific type for a particular system http://www.samsunghub.com/wp-content/uploads/2009/06/32GB-DDR3-RDIMM.jpg A 32GB DDR3 RAM module

  4. RAM packaging • RAM comes in many formats, including; • 30 / 72 -pin SIMM – Very old! • 168-pin DIMM • 184-pin DDR • 240-pin DDR2, DDR3 • 284-pin DDR4 (2013) • DIL (classic chip shape) • Flat, square high-density chips • Speed information may bevisible on the packaging

  5. RAM Performance • RAM is usually sold based on the “Peak transfer rate” in megabytes per second • DDR – 1600 - 3200 • DDR2 – 3200 to 8533 • DDR3 – 6400 to 17066 • DDR4 – double the data rate of DDR3 • Faster RAM is more expensive, as you might expect (but obsolete RAM can be expensive, too)

  6. Latency • Latency is the time taken from asking for the contents of a memory location to actually getting the answer • Several measures • tCAS – to access a column • tRAD – to access a row • tRP – to move from one row to another • tRAS – overall value • Expressed as a four figure number eg. • Typical DDR2 – 5-5-5-15 • DDR3 – DDR3-1066 – 7-7-7-21 DDR3-1333 – 7-7-7-24

  7. Cache • It is possible to buy RAM to run at any given CPU speed (2 to 4GHz) • But cheap mass-market bulk-storage RAM runs at around 200 to 800MHz (actual clock speed) • Typical systems use cache memory built into the CPU as a buffer between the CPU and the “slow” RAM • Cache can be 512KB to 8MB+ of very fast RAM • This is a bit like a shop having items on the shelves rather than in the warehouse...

  8. CMOS RAM • The CMOS RAM is special memory (sometimes a separate chip) that needs very little power to hold data • Key system settings are kept in CMOS, e.g. hard-drive settings and various motherboard settings • Most older PCs have 256 bytes of CMOS RAM • Motherboards often have a “jumper” connection to clear it – useful when completely reconfiguring a system

  9. ROM • Read Only Memory can be read but not written to • The computer needs some instructions when it starts up - these are in the BIOS ROM • Modern BIOS ROMs are so-called “flash ROM” • Flash ROMs are a form of EEPROM [firmware] • They allow BIOS updates without the need for physically swapping the ROMs • But there can be safety & security problems!

  10. Disc Drive types • Serial ATA drives started taking over in 2003 (start at 150MBps, now does 300MBps [2006], 600MBps [2008]) • SCSI is the Small Computer Systems Interface, a smart, fast but more expensive system commonly found in PC servers and older Macintosh systems (up to 80MBps) • SCSI has all but vanished at the low and mid-price points – only has a place with very fast drives 10

  11. IDE/ATA and SATA 11

  12. HDD - Hard Disc Drives • Change has been rapid over the last twenty years • “Fast mass-storage” once meant 80ms access time for 10MB hard drives, now 8ms access time and over 1000GB (one terabyte) is common • Matchbox-sized drives for cameras and media players can have over 500GB of storage room 12

  13. External Storage • Most external storage devices do not required manual installation. • Uses: • Expanding storage on notebook or PC • Transporting large amounts of data • Backing up • Offline data storage 13

  14. External Hard Disk • 3 different types of interface • USB • FireWire • External SATA • 3 different sizes • Full size – PC Hard disk size, 3.5 inches width • Portable size – Laptop hard disk size, 2.5 inches width • Pocket size (not popular as they have small capacity which can be replaced by Flash memory)

  15. Flash Memory • USB flash memory • 1MB/s (USB 1.1) or up to 60MB/s (USB 2.0) • Typically 1GB to 64GB of storage • U3 Smart USB Drive • Micro SD and Mini SD (HC) • Use in mobile phones, digital cameras, PDAs • Up to 64GB of storage • SD and SDHC • Use in PDAs, cameras – was popular • Up to 1GB of storage for SD • 64GB+ for SDHC

  16. Solid State Drives • According to Seagate, 2010 total market for notebook HD storage was 69 exabytes (69 billion gigabytes) (http://www.pcworld.com/businesscenter/article/217883/seagate_solidstate_disks_are_doomed_at_least_for_now.html) • 2011 forecast - a rise to 95 exabytes (Gartner) • In 2010 the total NAND memory manufactured was 11 exabytes, only 7% found its way into SSDs • It would take $250 billion investment in new fabrication plants to meet demand in 2011... • SSDs are not going to take over yet!

  17. Summary • We have discussed the basic of different types of storage that are used in the PCs • Memory Performance • Speed or Bandwidth of memory • Cache • CMOS RAM • ROM • Disc Drives • Flash Drives, SSDs

  18. References, Reading • DDR Memories Comparison and Overview • DDR4 SDRAMFrom Wikipedia • CPU cache From Wikipedia

More Related