1 / 14

Seagate ST506 format (old!)

Seagate ST506 format (old!). -//-. Gap1. Gap1. Id. Gap2. Data. Gap3. Id. Gap2. Data. Gap3. -//-. Sync Byte. Track. Sync Byte. Head. Sector. CRC. Data. CRC. Characteristics. Fixed (rare) or movable head Removable or fixed Single or double (usually) sided

honoria-merritt
Download Presentation

Seagate ST506 format (old!)

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. Seagate ST506 format (old!) -//- Gap1 Gap1 Id Gap2 Data Gap3 Id Gap2 Data Gap3 -//- Sync Byte Track Sync Byte Head Sector CRC Data CRC

  2. Characteristics • Fixed (rare) or movable head • Removable or fixed • Single or double (usually) sided • Single or multiple platter • Head mechanism • Contact (Floppy) • Fixed gap • Flying (Winchester)

  3. Fixed/Movable Head Disk • Fixed head • One read write head per track • Heads mounted on fixed ridged arm • Movable head • One read write head per side • Mounted on a movable arm

  4. Removable or Not • Removable disk • Can be removed from drive and replaced with another disk • Provides unlimited storage capacity • Easy data transfer between systems • Nonremovable disk • Permanently mounted in the drive

  5. Multiple Platter • One head per side • Heads are joined and aligned • Aligned tracks on each platter form cylinders • Data is striped by cylinder • reduces head movement • Increases speed (transfer rate)

  6. Multiple Platters

  7. Cylinders

  8. Floppy Disk • 8”, 5.25”, 3.5” • Small capacity • Up to 1.44Mbyte (2.88M never popular) • Slow • Universal • Cheap • Obsolete?

  9. Winchester Hard Disk (1) • Developed by IBM in Winchester (USA) • Sealed unit • One or more platters (disks) • Heads fly on boundary layer of air as disk spins • Very small head to disk gap • Getting more robust

  10. Winchester Hard Disk (2) • Universal • Cheap • Fastest external storage • Getting larger all the time • Multiple Gigabyte now usual

  11. Removable Hard Disk • ZIP • Cheap • Very common • Only 100M • JAZ • Not cheap • 1G • L-120 (a: drive) • Also reads 3.5” floppy • Becoming more popular? • All obsoleted by CD-R and CD-R/W?

  12. Speed • Seek time • Moving head to correct track • Startup time + traversal time. • (Rotational) latency • Waiting for data to rotate under head • Average: 1/2r • Transfer Time • b/rN • Access time = Seek + Latency + Transfer time • Transfer rate

  13. Timing of Disk I/O Transfer

  14. Reading Material • Stallings, chapter 6, pages: 163 - 174

More Related