Hardware and Software

Basic Types of Memory Chips

Secondary Storage and Output Devices

Cost Comparisons for Various Forms of Data Storage

Secondary Storage Access Methods

• Sequential access
• Access in the same order it was written
• Ex: Need to access memory location 5. Then, you need to go through 1, 2, 3, and 4 first.
• Direct access
• Directly access the location
• Faster than sequential access
• Sequential access storage devices (SASD)
• Direct access storage devices (DASD)

Secondary Storage Devices (1)

• Magnetic tapes: Similar to audio tapes, SASD
• Magnetic discs: Hard disk, DASD
• RAID: Redundant array of independent inexpensive disks
• Data stored more than once in one of the disks
• Even if one disk fails, data can still be retrieved
• SAN: Storage area network
• Consist of many storage devices
• Optical discs, DASD
• CD-ROM

Secondary Storage Devices (2)

• Magneto-optical discs
• Digital versatile discs (DVD): Up to 17 GB storage
• Memory cards
• Installed in a slot
• Portable
• Expandable storage: Removable disk cartridges
• Portable
• Zip drives

Types of Secondary Storage

Hard Disc

Storage Area Network

Digital Versatile Disc Player

Expandable Storage

Comparison of Secondary Storage Devices

Input Devices

• Personal computer input devices
• Keyboard
• Mouse
• Voice-recognition devices
• Microphone
• Software to convert voice into bits
• Digital computer cameras
• Record images and video
• Terminals
• Connects to a powerful server for computations
• Scanning devices
• Page
• Handheld
• Touch-sensitive Screens