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Storage Devices (definition (gygabyte:a unit of information equal to one…
Storage Devices
definition
gygabyte:a unit of information equal to one thousand million (109) or, strictly, 230 bytes.
terrabyte:a unit of information equal to one million million (1012) or, strictly, 240 bytes.
megabyte:a unit of information equal to one million or, strictly, 1,048,576 bytes.
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Backup
what is backup?:it refers to the copying of files/data to a different medium(disk,tape,flash drive,etc.)in case of a problem with the main seconadary storage device.
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Types of access
Serial / sequential
Serial access is where data records are stored one after the other with no regard to the order. This is usually an unprocessed file.
Serial files are read by starting at the beginning and reading through every record until you find the one that you want. The records are in no particulat order so you need to start of the beginning to make sure you don't miss a record.
Magnetic Tape and disks can be used to store serial files.
Direct/Random
Sometimes referred to as machine access or random access, direct access is a term used to describe the ability of a computer to immediately locate and retrieve data from a storage device.
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Bit:A bit (short for binary digit) is the smallest unit of data in a computer. A bit has a single binary value, either 0 or 1. Although computers usually provide instructions that can test and manipulate bits, they generally are designed to store data and execute instructions in bit multiples called bytes.
Byte:a group of binary digits or bits (usually eight) operated on as a unit.
A byte considered as a unit of memory size.