Computer Storage Devices
Hard drive:
A hard disk drive (sometimes abbreviated as Hard drive, HD, or HDD) is a device used to permanently store and also retrieve information. There are many variations, but their sizes are generally 3.5" and 2.5" for desktop and laptop computers respectively. A hard drive consists of one or more platters to which data is written using a magnetic head, all inside of an air-sealed casing. Internal hard disks reside in a drive bay, connect to the motherboard using an ATA, SCSI, or SATA cable, and are powered by a connection to the PSU (power supply unit). The images below show the components of a hard drive inside of both desktop and laptop computers.
A hard disk drive (sometimes abbreviated as Hard drive, HD, or HDD) is a device used to permanently store and also retrieve information. There are many variations, but their sizes are generally 3.5" and 2.5" for desktop and laptop computers respectively. A hard drive consists of one or more platters to which data is written using a magnetic head, all inside of an air-sealed casing. Internal hard disks reside in a drive bay, connect to the motherboard using an ATA, SCSI, or SATA cable, and are powered by a connection to the PSU (power supply unit). The images below show the components of a hard drive inside of both desktop and laptop computers.
The hard disk was first introduced on September 13, 1956.
How is data read and stored on a hard drive?
Data sent to and from the hard drive is interpreted by the disk controller, which tells the hard drive what to do and how to move the components within the drive. When the operating system needs to read or write information, it examines the hard drive's File Allocation Table (FAT) to determine file location and available write areas. Once they have been determined, the disk controller instructs the actuator to move the read/write arm and align the read/write head. Because files are often scattered throughout the platter, the head needs to move to different locations to access all information.
All information stored on a traditional hard drive, like the above example, is done magnetically. After completing the above steps, if the computer needs to read information from the hard drive, it would read the magnetic polarities on the platter. One side of the magnetic polarity is 0, and the other is 1. Reading this as binary data, the computer can understand what the data is on the platter. For the computer to write information to the platter, the read/write head aligns the magnetic polarities, writing 0's and 1's that can be read later.
External and Internal hard drives
Although most hard drives are internal, there are also stand-alone devices called external hard drives, which can back up data on computers and expand the available disk space. External drives are often stored in an enclosure that helps protect the drive and allows it to interface with the computer, usually over USB or eSATA. A great example of an external backup device that supports multiple hard drives is the Drobo.
External hard drives come in many shapes and sizes. Some are large, about the size of a book while others are about the size of a cell phone. External hard drives can be very useful since they usually offer more space than a jump drive and are still portable. The picture to the right is an example of a laptop hard disk drive enclosure from Adaptec. The user may install any size of laptop hard drive they desire into the enclosure and connect via USB port to the computer.
DD being replaced by SSD:
Solid State Drives (SSDs) have started to replace hard disk drives (HDDs) because of the distinct performance advantages they have over HDD, including faster access times and lower latency. While SSD is becoming more and more popular, HDD will continue to be in desktop computers with SSD because of the available capacity and value per dollar that HDD offers over SSD.
Modem:
Short for MODulator/DEModulator, the first Modem known as the Dataphone, which was first released by AT&T in 1960. It later became more common for home users when Dennis Hayes and Dale Heatherington released the 80-103A Modem in 1977.
Short for MODulator/DEModulator, the first Modem known as the Dataphone, which was first released by AT&T in 1960. It later became more common for home users when Dennis Hayes and Dale Heatherington released the 80-103A Modem in 1977.
A Modem is a hardware device that allows a computer to send and receive information over telephone lines by converting digital data into an analog signal used on phone lines. In the picture below, is an example of an internal expansion card Modem. Click the image to get a description of each of the components found on the card.
Modems are referred to as an asynchronous device, meaning that the device transmits data in an intermittent stream of small packets. Once received, the receiving system then takes the data in the packets and reassembles it into a form the computer can use.
The above chart represents how an asynchronous transmission would be transmitted over a phone line. In asynchronous communication, one byte (eight bits) is transferred within one packet, which is equivalent to one character. However, for the computer to receive this information, each packet must contain a Start and a Stop bit; therefore, the complete packet would be ten bits. In the above chart is a transmission of the word HI, which is equivalent to two bytes (16 bits).
Stop
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Data
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Start
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Stop
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Data
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Start
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Packet
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Packet
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The above chart represents how an asynchronous transmission would be transmitted over a phone line. In asynchronous communication, one byte (eight bits) is transferred within one packet, which is equivalent to one character. However, for the computer to receive this information, each packet must contain a Start and a Stop bit; therefore, the complete packet would be ten bits. In the above chart is a transmission of the word HI, which is equivalent to two bytes (16 bits).
You did not grow up on a dial-up Modem or you are nostalgic, click the example MP3 link to the left, to hear a Modem connecting to the Internet. In this audio file, you hear the Modem dialing a phone number and then communicating with the other Modem over the phone line. The squealing noise heard after the phone number is the Modem establishing a connection (handshaking). Once the connection is established the Modem goes silent.
Types of computer Modems: Below are the four versions of a computer Modem found in computers.
Onboard Modem:
onboard Modem is a Modem that is built into the computer motherboard. These Modems cannot be removed but can be disabled through a Jumper or CMOS Setup.
Internal Modem:
Internal Modem connects to a PCI slot inside a newer desktop computer or ISA slot on an older computer. The Internal Modem shown at the beginning of this document is an example of a PCI Modem.
External Modem:
External Modem is located within a box and is hooked up externally to the computer, usually the Serial Ports or USB port. The picture is an example of an external USR robotics Modem.
Internal Modem connects to a PCI slot inside a newer desktop computer or ISA slot on an older computer. The Internal Modem shown at the beginning of this document is an example of a PCI Modem.
External Modem:
External Modem is located within a box and is hooked up externally to the computer, usually the Serial Ports or USB port. The picture is an example of an external USR robotics Modem.
Removable Modem:
Removable Modem that is used with an older laptops PCMCIA slot and is removed when you need the PCMCIA slot for another device, but is not planning on using the Modem.
NIC:(Network Interface Card):-
The bottom picture shows a PC Card, more specifically the SMC EZ Card 10/100 wireless network card; found in laptop computers that do not have onboard wireless capabilities.
SD Card:-
Short for Secure Digital Card, the SD Card is one of the more common types of memory cards used with electronics. The SD technology is used by over 400 brands of electronic equipment and over 8000 different models, including digital cameras can cell phones. It is considered the industry standard due to its wide use. The SD card has a recognized maximum storage capacity of 2GB (gigabytes), but 4GB versions do exist. The 4GB versions were not widely used due to issues & limitations with the technology at that capacity. The three versions of the SD card, along with their physical dimensions, are shown below:
· SD - 32mm x 24mm x 2.1mm.
Touch screen:-
A touch screen is a monitor or other flat surface with a sensitive panel directly on the screen that registers the touch of a finger as an input. Instead of being touch-sensitive, some touch screens use beams across the screen to create a grid that senses the presence of a finger. A touch screen allows the user to interact with a device without a mouse or keyboard and is used with smartphones, tablets, computer screens, and information kiosks.
How do you use the touch screen?
Note: Not all touch screens act the same, and any of the below actions may react differently on your device.
Double-tap –Depending on where you are a double-tap can have different functions. For example, in a browser double-tapping, the screen zooms into where you double-tapped. Double-tapping text in a text editor selects a word or section of words.
Touch and hold – Gently touching and holding your finger over an object selects or highlights the object. For example, you could touch and hold an icon and then drag it somewhere else on the screen or highlight text.
Swipe –Swiping your finger across the screen scrolls the screen in that direction. For example, pressing the finger at the bottom of the screen and quickly moving it up (swiping) scrolls the screen down.
Pinch –Placing two fingers on the screen and then pinching them together zooms out and pinching your fingers together and then moving them away from each other zooms into where you started.
Jump drive: Alternatively referred to as a USB flash drive, data stick, pen drive, memory unit, key chain drive, and thumb drive, a jump drive is a portable storage device. It is often the size of a human thumb (hence the name) and it connects to a computer via USB port. Today, flash drives are available in sizes such as 256MB, 512MB, 1GB, 5GB, and 16GB and are an easy way to transfer and store information. The picture is an example of the SanDisk Cruzer Micro 16GB flash drive and a good example of a flash drive. As can be seen in this picture, the drive has a small casing that stores the flash memory connected to a USB connection that is plugged into the USB port on your computer. Unlike a hard drive, the flash drive only contains an integrated circuit memory board capable of storing information and has no movable parts.
How do I use a flash drive?
A flash drive can be used like any drive on your computer. Start by inserting the flash drive into a front or back USB port or to a USB hub. Once connected open My Computer and you should see the drive as "Removable Disk", "Flash drive", or as the manufacturer's name. Once the drive has been determined you can copy any file you want and paste them into the flash drive or drag-and-drop the files to the flash drive icon.
SD Card:-
Short for Secure Digital Card, the SD Card is one of the more common types of memory cards used with electronics. The SD technology is used by over 400 brands of electronic equipment and over 8000 different models, including digital cameras can cell phones. It is considered the industry standard due to its wide use. The SD card has a recognized maximum storage capacity of 2GB (gigabytes), but 4GB versions do exist. The 4GB versions were not widely used due to issues & limitations with the technology at that capacity. The three versions of the SD card, along with their physical dimensions, are shown below:
· SD - 32mm x 24mm x 2.1mm.
Touch screen:-
A touch screen is a monitor or other flat surface with a sensitive panel directly on the screen that registers the touch of a finger as an input. Instead of being touch-sensitive, some touch screens use beams across the screen to create a grid that senses the presence of a finger. A touch screen allows the user to interact with a device without a mouse or keyboard and is used with smartphones, tablets, computer screens, and information kiosks.
How do you use the touch screen?
Note: Not all touch screens act the same, and any of the below actions may react differently on your device.
Double-tap –Depending on where you are a double-tap can have different functions. For example, in a browser double-tapping, the screen zooms into where you double-tapped. Double-tapping text in a text editor selects a word or section of words.
Touch and hold – Gently touching and holding your finger over an object selects or highlights the object. For example, you could touch and hold an icon and then drag it somewhere else on the screen or highlight text.
Swipe –Swiping your finger across the screen scrolls the screen in that direction. For example, pressing the finger at the bottom of the screen and quickly moving it up (swiping) scrolls the screen down.
Pinch –Placing two fingers on the screen and then pinching them together zooms out and pinching your fingers together and then moving them away from each other zooms into where you started.
Jump drive: Alternatively referred to as a USB flash drive, data stick, pen drive, memory unit, key chain drive, and thumb drive, a jump drive is a portable storage device. It is often the size of a human thumb (hence the name) and it connects to a computer via USB port. Today, flash drives are available in sizes such as 256MB, 512MB, 1GB, 5GB, and 16GB and are an easy way to transfer and store information. The picture is an example of the SanDisk Cruzer Micro 16GB flash drive and a good example of a flash drive. As can be seen in this picture, the drive has a small casing that stores the flash memory connected to a USB connection that is plugged into the USB port on your computer. Unlike a hard drive, the flash drive only contains an integrated circuit memory board capable of storing information and has no movable parts.
How do I use a flash drive?
A flash drive can be used like any drive on your computer. Start by inserting the flash drive into a front or back USB port or to a USB hub. Once connected open My Computer and you should see the drive as "Removable Disk", "Flash drive", or as the manufacturer's name. Once the drive has been determined you can copy any file you want and paste them into the flash drive or drag-and-drop the files to the flash drive icon.
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computer storage devices, storage devices of a computer, memory of a computer, Parts of computer
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