Memory Characteristics and Functions
(continued)
• Types of memory:
– Random access memory (RAM):
• Temporary and volatile
– Read-only memory (ROM):
• Nonvolatile
• Provides permanent storage for data and instructions
that do not change
Fundamentals of Information Systems, Sixth Edition 16
Multiprocessing
• Multiprocessing:
– Simultaneous execution of two or more instructions
at the same time
• Multicore microprocessor:
– Combines two or more independent processors into
a single computer
Fundamentals of Information Systems, Sixth Edition 17
Fundamentals of Information Systems, Sixth Edition 18
Multiprocessing (continued)
• Parallel computing:
– Simultaneous execution of the same task on multiple
processors to obtain results faster
• Grid computing:
– Use of a collection of computers to work in a
coordinated manner to solve a common problem
Fundamentals of Information Systems, Sixth Edition 19
Secondary Storage and Input and
Output Devices
• Secondary storage:
– Compared with memory, offers the advantages of
nonvolatility, greater capacity, and greater economy
– Considerably slower than memory
Access Methods
• Sequential access:
– Data must be retrieved in the order in which it is
stored
– Devices used called sequential access storage
devices (SASDs)
• Direct access:
– Records can be retrieved in any order
– Devices used are called direct access storage
devices (DASDs)
Fundamentals of Information Systems, Sixth Edition 20
Secondary Storage Devices
• Magnetic tapes:
– Primarily for storing backups of critical organizational
data
• Magnetic disks:
– Direct-access storage device
• Redundant array of independent/inexpensive disks
(RAID):
– Method of storing data that generates extra bits of
data from existing data
• Virtual tape:
– Storage technology for less frequently needed data
Fundamentals of Information Systems, Sixth Edition 21
Secondary Storage Devices
(continued)
• Storage area network:
– Uses computer servers, distributed storage devices,
and networks to tie everything together
• Optical discs:
– Common form of optical disc on which data cannot
be modified once it has been recorded
• Digital video disc (DVD):
– Storage medium used to store software, video
games, and movies
Fundamentals of Information Systems, Sixth Edition 22
Secondary Storage Devices
(continued)
• Solid state secondary storage devices:
– Store data in memory chips rather than magnetic or
optical media
– Have few moving parts, so they are less fragile than
hard disk drives
– Disadvantages of SSD:
• High cost per GB of data storage
• Lower capacity compared to current hard drives
Fundamentals of Information Systems, Sixth Edition 23
Fundamentals of Information Systems, Sixth Edition 24
Input Devices
• Devices used to input general types of data:
– Personal computer input devices
– Speech recognition technology
– Digital cameras
– Touch-sensitive screens
– Optical data readers
– Magnetic ink character recognition (MICR) devices
– Pen input devices
– Magnetic stripe card
– Radio Frequency Identification