1. Exploring the Digital Domain Secondary Memory and Input/Output

2. Input/Output –exchanging data and instructions between the user and the computer Secondary Storage –auxiliary storage for data and instructions I/O Subsystem

3. backup or alternative storage in place of (volatile) RAM cheaper, mass storage for long term use secondary memory devices (and media) are distinguished by their capacities, speed, and cost Secondary Memory (Storage)

4. 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

5. 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

6. Memory Hierarchy I

7. Memory Hierarchy II

8. stores data represented by magnetized particles in linear tracks magnetized clusters or domains are aligned to represent binary codes Magnetic Tape

10. LONGITUDINAL –older format used for record-keeping SERPENTINE –used for system backups HELICAL SCAN –high capacity formulation used for system backups and archives Magnetic Tape Formats

11. Longitudinal (9-track)

12. Serpentine (QIC)

13. magnetic hard and floppy disks removable hard disks optical discs –CD-ROM, CD-R, –WORM, –magneto-optical GEOMETRY: TRACKS and SECTORS GEOMETRY: TRACKS and SECTORS Direct Access Storage Devices

14. 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

15. 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

16. FLOPPY DISKS –5.25 and 3.5 inch diskettes –1.44 – 2.88 MBytes capacity –access: drive speeds – 600 r.p.m. –inexpensive, archival uses for small amounts of data HARD DISKS –3.5 inch has approx 3,000 tracks per side –multiple disk, sides (cylinders) –high capacity –access: drive speeds – 3,600 up to 7,200 r.p.m. –on-line storage Magnetic Disks

17. 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) Disk vs. File Organization

18. Compact Disc–Read Only Memory (CD-ROM) –archived and published information –high capacity Compact Disc–Recordable (CD-R) –recordable –readable using CD-ROM technology Write Once, Read Many (WORM) –high capacity archival storage Magneto-Optical Discs –erasable, high capacity, on-line storage alternative Digital Versatile Discs (DVD) –Very high capacity, read-only storages Optical Discs

19. 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

20. 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

21. Magneto-Optical –combines magnetic and optical technologies –erasable, readable-writable storage –very high capacity –not yet economical Digital Versatile Disc (DVD) –successor to CD-ROM technology –very high capacity read-only storage –multiple disc, multiple sided storage Other Optical Media

22. keyboard mouse scanners (flatbed, slide, and drum) digital cameras sound digitizers MIDI (Musical Instrument Digital Interface) Video digitizers Input Peripherals

23. video display monitors –monochrome and color –CRT and LCD Output Peripherals

24. cathode ray tube (CRT) phosphors excited by electron gun beams RGB composite color horizontal scanning pattern to refresh phosphors CRT technology

25. video display monitors –monochrome and color –CRT and LCD printers –character, line, and page Output Peripherals

26. CHARACTER dot matrix –low-cost, text and graphic printers –slow-speed, low quality inkjet –medium-priced –general-purpose PAGE laser printers –high-quality –assortment of sizes, performance, and cost Printers

27. video display monitors –monochrome and color –CRT and LCD printers –character, line, and page sound and voice output MIDI synthesizers Output Peripherals