When we talk about ‘storing’ data, we mean putting the data in a known place. We can later come back to that place and get our data back again.
‘Writing’ data or ‘saving’ data are other ways of saying ‘storing’ data.
‘Reading’ data, ‘retrieving’ data or ‘opening’ a file are ways of saying that we are getting our data back from its storage location.
Backing Storage vs Main Memory
Main Memory
Main memory (sometimes known as internal memory or primary storage) is another name for RAM (and ROM).
Main memory is usually used to store data temporarily. In the case of RAM, it is volatile (this means that when power is switched off all of the data in the memory disappears).
Main memory is used to store data whilst it is being processed by the CPU. Data can be put into memory, and read back from it, very quickly
Backing Storage
Backing storage (sometimes known as secondary storage) is the name for all other data storage devices in a computer: hard-drive, etc.
Backing storage is usually non-volatile, so it is generally used to store data for a long time.
Storage Media & Devices
he device that actually holds the data is known as the storage medium (‘media’ is the plural).
The device that saves data onto the storage medium, or reads data from it, is known as the storage device.
Sometimes the storage medium is a fixed (permanent) part of the storage device, e.g. the magnetic coated discs built into a hard drive
Sometimes the storage medium is removable from the device, e.g. a CD-ROM can be taken out of a CD drive.
Accessing Stored Data
We refer to a collection of data stored in a computer system as a ‘file’. Files are often organised into ‘folders’.
Whenever you click ‘Save’ in an application, burn files to a CD-R, copy music onto your MP3 player, or drag and drop a file onto memory stick, you are using storage devices - devices that can store and retrieve data.
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Serial / Sequential Access
A serial (or sequential) access storage device is one that stores files one-by-one in a sequence.
A non-computer serial access device that will be familiar to you is a VHS videotape. Because video is stored on a long piece of tape, when TV shows are recorded onto the tape, they go on one-by-one, in order...
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If you want to watch a show that you recorded earlier, you have to rewind / fast-forward through all other shows until you find it.
The shows are only accessible in the same order that you recorded them. This type of one-by-one storage and access is called serial access.
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Systems that store things on tape (video, music, computer data, etc.) are always serial access
Direct / Random Access
A direct (or ‘random’) access storage device is one that stores files so that they can be instantly accessed - there is no need to search through other files to get to the one you want.
An example of a direct access device would be a DVD movie. Unlike the VHS videotape movie, you can jump to any scene on a DVD.
All parts of the DVD are directly accessible. This type of file storage is called direct access.
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Assignments
1.CD-ROM: Compact Disk-Read Only Memory
CD-R: Compact Disk-Recordable
CD-RW: Compact Disk- ReWritable
DVD: Digital Video Disk
2. It means you can read the information in them (music...), however you cannot modify it.
3.DVDs are becoming increasingly popular because of how accessible they are and how you can take your information everywhere without taking that much space.
4.a) Transfer a word-processed document from one computer to another: A floppy disk as it does not have a lot of memory taking onto account the fact that word documents are not even as big as one MB.
b)Regularly back up data on a computer network: CD-R because it's suitable for this task and has a large memory capacity; which makes
c)Distribute a full-length feature film with accompanying data: DVD because it can hold up a large amount of data (up tp 17Gb) and
Table of Contents
Notes
Assignments
Homework
Notes
Mindmap
What is Data Storage?
When we talk about ‘storing’ data, we mean putting the data in a known place. We can later come back to that place and get our data back again.‘Writing’ data or ‘saving’ data are other ways of saying ‘storing’ data.
‘Reading’ data, ‘retrieving’ data or ‘opening’ a file are ways of saying that we are getting our data back from its storage location.
Backing Storage vs Main Memory
Main Memory
Main memory (sometimes known as internal memory or primary storage) is another name for RAM (and ROM).
Main memory is usually used to store data temporarily. In the case of RAM, it is volatile (this means that when power is switched off all of the data in the memory disappears).
Main memory is used to store data whilst it is being processed by the CPU. Data can be put into memory, and read back from it, very quickly
Backing Storage
Backing storage (sometimes known as secondary storage) is the name for all other data storage devices in a computer: hard-drive, etc.
Backing storage is usually non-volatile, so it is generally used to store data for a long time.
Storage Media & Devices
he device that actually holds the data is known as the storage medium (‘media’ is the plural).The device that saves data onto the storage medium, or reads data from it, is known as the storage device.
Sometimes the storage medium is a fixed (permanent) part of the storage device, e.g. the magnetic coated discs built into a hard drive
Sometimes the storage medium is removable from the device, e.g. a CD-ROM can be taken out of a CD drive.
Accessing Stored Data
We refer to a collection of data stored in a computer system as a ‘file’. Files are often organised into ‘folders’.Whenever you click ‘Save’ in an application, burn files to a CD-R, copy music onto your MP3 player, or drag and drop a file onto memory stick, you are using storage devices - devices that can store and retrieve data.
Serial / Sequential Access
A serial (or sequential) access storage device is one that stores files one-by-one in a sequence.A non-computer serial access device that will be familiar to you is a VHS videotape. Because video is stored on a long piece of tape, when TV shows are recorded onto the tape, they go on one-by-one, in order...
If you want to watch a show that you recorded earlier, you have to rewind / fast-forward through all other shows until you find it.
The shows are only accessible in the same order that you recorded them. This type of one-by-one storage and access is called serial access.
Systems that store things on tape (video, music, computer data, etc.) are always serial access
Direct / Random Access
A direct (or ‘random’) access storage device is one that stores files so that they can be instantly accessed - there is no need to search through other files to get to the one you want.An example of a direct access device would be a DVD movie. Unlike the VHS videotape movie, you can jump to any scene on a DVD.
All parts of the DVD are directly accessible. This type of file storage is called direct access.
Assignments
1.CD-ROM: Compact Disk-Read Only Memory
CD-R: Compact Disk-Recordable
CD-RW: Compact Disk- ReWritable
DVD: Digital Video Disk
2. It means you can read the information in them (music...), however you cannot modify it.
3.DVDs are becoming increasingly popular because of how accessible they are and how you can take your information everywhere without taking that much space.
4.a) Transfer a word-processed document from one computer to another: A floppy disk as it does not have a lot of memory taking onto account the fact that word documents are not even as big as one MB.
b)Regularly back up data on a computer network: CD-R because it's suitable for this task and has a large memory capacity; which makes
c)Distribute a full-length feature film with accompanying data: DVD because it can hold up a large amount of data (up tp 17Gb) and
d)Distribute 500 Mb of application software:
Homework
.