Must have CD recorder or CD-R drive Cannot erase disc’s contents CD-R ( c ompact d isc- r ecordable) — c disc you can write on once CD-RW ( c ompact d isc- r e w ritable) — ce erasable disc you can write on multiple times Must have CD-RW software and CD-RW drive
Optical Discs What is a DVD-ROM (digital versatile disc-ROM or digital video disc-ROM)? High capacity disc capable of storing 4.7 GB to 17 GB Must have DVD-ROM drive or DVD player to read DVD-ROM Stores databases, music, complex software, and movies
Optical Discs How does a DVD-ROM store data? Two layers of pits are used, lower layer is semitransparent so laser can read through Some are double-sided Blu-Ray discs currently have a storage capacity of up to 27 GB
Magnetic Tape Magnetic tape is an older storage technology that still used for secondary storage of large volumes of information. The principle advantages its inexpensiveness, its relative stability and its ability to store very large quantities of information. The disadvantages its sequentially stored data and its relative slowness compared to the speed of secondary storage media.
Tape What is tape ? – Magnetically coated plastic ribbon capable of storing large amounts of data at low cost – Primarily used for backup
PC Cards What is a PC Card ? Adds capabilities to computer Credit-card-sized device commonly used in notebook computers
Primary Storage Primary storage is a category of computer storage, often called main memory . Has three functions: Stores all or part of the program that is being executed. Stores the operating system programs that manage the operation of the computer. Holds data that the program is using. Data and program are placed in primary storage before processing, between processing steps and after processing has ended prior to being returned to secondary storage or released as output.
Memory How is memory measured? Term Abbreviation Approximate Size Kiloby KB or K 1 thousand bytes Megabyte MB 1 million bytes Gigabyte GB 1 billion bytes Terabyte TB 1 trillion bytes By number of bytes available for storage
Modern primary storage devices include: Random access memory (RAM) is used for short-term storage of data or program instructions. RAM is volatile. Its contents will be lost when the computer’s electric supply is disrupted by a power outage or when the computer turned of. Read-only memory (ROM) can only be read from. It cannot be written to. ROM chips come from the manufacturer with programs already burned in, or stored. ROM is used in general-purpose computers to store important or frequently used programs, such as computing routine for calculating the square roots of numbers.
Memory What is random access memory ( RAM ) ?
- Spring '18
- Binary numeral system, Endrias Haile, Debrebrhan University