1. GRAP 3175 Computer Applications for Drafting Unit II Computer Hardware

2. Secondary Storage

3. Nonvolatile storage that is external to the main memory Used for: –Storage of large amounts of data –Permanent or long-term storage –Backups Hardware is input/output (I/O) device

4. Three Secondary Storage Media Magnetic tape Magnetic disks Optical technology

5. Three Main Characteristics How much storage do you need? –Totals bytes –Density How fast do you need it? –Data access time -- milliseconds –Data transfer rate -- megabytes per minute How much will it cost? –Fixed cost –Cost per megabyte

6. Type of Storage Device Local On-line Near-on-line Backup Archival Distribution Hard Disk Server-based magnetic & optical drives Optical jukeboxes & tape changers Tape drives & changers Tape drives & optical disk Floppy disks, recordable CR-ROMS, & magnetic tape

7. Evaluation Criteria Throughput (speed) -- transfer rate Access time (delay) Capacity Drive cost Media cost Archival life

8. Type of Storage Criteria On-line Near-on-line Backup Archival Distribution High throughput, fast access time & high capacity Very high capacity, low media cost, & long archival life High capacity & low drive cost Low media cost & long archival life High capacity & low media cost

9. Magnetic Tape 1/4, 1/2, 4mm, 8mm, or VHS Tape drive (I/O) Sequential Storage Inexpensive -- backup storage

10. Reel-to-reel Tape 21MB - 170MB Old technology -- slower access

11. Cassette Tape QIC -- Quarter inch cartridge (1/4) –2.5GB to 4GB DAT -- Digital audio tape (4mm) –20GB DDS-3 -- Digital data storage (4mm) –12GB/24GB

12. Cartridge Tape DTF -- Digital tape format (1/2) –42GB DLT -- Digital linear tape (1/2) –35GB/70GB AIT -- Advanced Intelligent (8mm) –25GB VHS -- Video tape SD1 -- 19mm –100GB

14. Magnetic Disk Direct access Ability to hold more data in a smaller space Faster data access speeds

15. Floppy Disk 8, 5 1/4, & 3 1/2 I/O device -- floppy disk drive

16. Floppy Disk Capacities DOS 5 1/4 DSDD 5 1/4 DSHD 3 1/2 DSDD 3 1/2 DSHD DSED Floptical SuperDisk 360k 1.2MB 720k 1.44MB 4MB 21MB 120MB

17. Floppy Disk Capacities MAC 3 1/2 DSDD 3 1/2 DSHD Floptical SuperDisk 800k 1.4MB 21MB 120MB

20. Hard Disk I/O device -- hard disk drive Read/write head

21. Fixed Disk 1 - 5.25 Interfaces –IDE (EIDE) - Integrated Drive Electronics Only daisy chain 2 drives up to 27 GB ULTRA IDE, EIDE –SCSI - Small Computer Systems Interface Daisy up to 6 devices up to 73 GB SCSI-2, SCSI Ultra2/Wide

23. Removable Cartridge IOMEGA –ZIP –JAZ –JAZ 2 –Parallel or SCSI SPARQ QUEST –100MB –250MB –1GB –2GB –4.7GB

24. Optical Technology Overview –Large storage capacity –removable –not magnetic Optical Disk –Size –Uses data, video, audio

25. CD-ROM CD-ROM -- Compact Disk, Read-only Memory 650MB CD-R CD-RW 40x

26. DVD DVD -- Digital Videodisk up to 10GB DVD-RAM up to 5.25GB

27. WORM WORM -- Write Once, Read Many 200GB

28. Erasable Drive Magneto-Optical –3.5 MO -- 1.3GB –5.25 MO -- 5.2GB

29. Others Optical Card Optical Tape