1. Storing Data On Your Computer Chapter 12, Exploring the Digital Domain

2. In this chapter... how various storage technologies support processing how data is transferred to and from the processor two classes of secondary memory DASD SASD How data is organized on magnetic and optical media You will learn about

3. RAM is composed of integrated units SDRAM-- Synchronous Dynamic RAM DIMMs--Dual Inline Memory Modules Main Memory

4. Connecting to the Processor a bus is a connection between components classifying buses data width speed early designs featured a single system bus

5. Connecting to the Processor Modern designs feature two-tier chipset “northbridge”-- controller connecting CPU with memory, graphics controller “southbridge”-- controller connecting I/O and other devices

6. Memory Hierarchy I

7. Memory Hierarchy II

8. RANDOM ACCESS items are independently addressed access time is constant DIRECT ACCESS items are independently addressed in regions access time is variable—though not significantly SEQUENTIAL ACCESS items are organized in sequence (linearly) access time is significantly variable Types of Memory Access

9. SEQUENTIAL ACCESS STORAGE DEVICES AND MEDIA (SASD) magnetic tape DIRECT ACCESS STORAGE DEVICES AND MEDIA (DASD) magnetic floppy disks magnetic hard disks optical discs Secondary Memory

10. magnetic hard and floppy disks removable hard disks optical discs CD-ROM, CD-R, CD-RW, DVD GEOMETRY: TRACKS and SECTORS GEOMETRY: TRACKS and SECTORS Direct Access Storage Devices

11. CAV — constant angular velocity (e.g., floppy and hard disks) CLV — constant linear velocity (e.g., optical discs) Zoned CAV — number of sectors depends upon zone DASD Media

12. SEEK — controller advances read/write head to proper track LATENCY — waits for proper sector to rotate under head READ/WRITE — disk head scans the sector for read or write Direct Access

13. FLOPPY DISKS 5.25 and 3.5 inch diskettes CAV 1.44 – 2.88 MBytes capacity access: drive speeds – 600 r.p.m. inexpensive, archival uses for small amounts of data offline storage HARD DISKS 3.5 inch has approx 10- 30K tracks per side ZCAV multiple disk, sides (cylinders) high capacity access: drive speeds – 5,400; 7,200 r.p.m. and higher on-line storage Magnetic Disks

14. data is stored in blocks blocks occupy sectors sectors on tracks files have names files are indefinite in size files may be updated (in part or whole) directory entries record file data file allocation table keeps track of file pieces Disk vs. File Organization

15. based on CDDA technology CLV geometry density: 16,000 tpi up to 650 MBytes nonerasable, nonwriteable storage discs are mastered, pressed (mass production) multispeeds drives common CD-ROM

16. discs are “burnt” one at a time high intensity laser beam used for recording pregrooved tracks low intensity beam for reading attributes similar to CD- ROM CD–R

17. CD-RW CD-ReWritable-- writable, erasable disc optical phase-change recording Erased, written up to 1,000 times UDF (Universal Disk Format) variable-length packets fixed-length packets

18. DVD Digital Versatile Disc second generation CD-ROM higher capacity: higher data density multiple sides multiple layers