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Inside: Platters and Heads
In order to increase the amount of information the drive can store, most hard disks have multiple platters. This drive has three platters and six read/write heads:
The mechanism that moves the arms on a hard disk has to be incredibly fast and precise. It can be constructed using a high-speed linear motor.
Many drives use a "voice coil" approach -- the same technique used to move the cone of a speaker on your stereo is used to move the arm.
The World Technology Network
Inside: Beneath the Board
Underneath the board are the connections for the motor that spins the platters, as well as a highly-filtered vent hole that lets internal and external air pressures equalize:
Removing the cover from the drive reveals an extremely simple but very precise interior:
In this picture you can see:
The platters - These typically spin at 3,600 or 7,200 rpm when the drive is operating. These platters are manufactured to amazing tolerances and are mirror-smooth (as you can see in this interesting self-portrait of the author... no easy way to avoid that!).
The arm - This holds the read/write heads and is controlled by the mechanism in the upper-left corner. The arm is able to move the heads from the hub to the edge of the drive. The arm and its movement mechanism are extremely light and fast. The arm on a typical hard-disk drive can move from hub to edge and back up to 50 times per second -- it is an amazing thing to watch!
World Technology Corporation
Inside: Electronics Board
The best way to understand how a hard disk works is to take a look inside. (Note that OPENING A HARD DISK RUINS IT, so this is not something to try at home unless you have a defunct drive.) Here is a typical hard-disk drive: It is a sealed aluminum box with controller electronics attached to one side. The electronics control the read/write mechanism and the motor that spins the platters. The electronics also assemble the magnetic domains on the drive into bytes (reading) and turn bytes into magnetic domains (writing). The electronics are all contained on a small board that detaches from the rest of the drive:
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Cassette Tape vs. Hard Disk
Let's look at the big differences between cassette tapes and hard disks:
The magnetic recording material on a cassette tape is coated onto a thin plastic strip. In a hard disk, the magnetic recording material is layered onto a high-precision aluminum or glass disk. The hard-disk platter is then polished to mirror-type smoothness.
With a tape, you have to fast-forward or reverse to get to any particular point on the tape. This can take several minutes with a long tape. On a hard disk, you can move to any point on the surface of the disk almost instantly.
In a cassette-tape deck, the read/write head touches the tape directly. In a hard disk, the read/write head "flies" over the disk, never actually touching it.
The tape in a cassette-tape deck moves over the head at about 2 inches (about 5.08 cm) per second. A hard-disk platter can spin underneath its head at speeds up to 3,000 inches per second (about 170 mph or 272 kph)!
The information on a hard disk is stored in extremely small magnetic domains compared to a cassette tape's. The size of these domains is made possible by the precision of the platter and the speed of the medium.
¬ Because of these differences, a modern hard disk is able to store an amazing amount of information in a small space. A hard disk can also access any of its information in a fraction of a second.
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Hard Disk Basics
Hard disks were invented in the 1950s. They started as large disks up to 20 inches in diameter holding just a few megabytes. They were originally called "fixed disks" or "Winchesters" (a code name used for a popular IBM product). They later became known as "hard disks" to distinguish them from "floppy disks." Hard disks have a hard platter that holds the magnetic medium, as opposed to the flexible plastic film found in tapes and floppies.
At the simplest level, a hard disk is not that different from a cassette tape. Both hard disks and cassette tapes use the same magnetic recording techniques described in How Tape Recorders Work. Hard disks and cassette tapes also share the major benefits of magnetic storage -- the magnetic medium can be easily erased and rewritten, and it will "remember" the magnetic flux patterns stored onto the medium for many years.
In the next section, we'll talk about the main differences between casette tapes and hard disks.
Introduction to Computers - Computer Hardware
How Hard Disks Work
Nearly every desktop computer and server in use today contains one or more hard-disk drives. Every mainframe and supercomputer is normally connected to hundreds of them. You can even find VCR-type devices and camcorders that use hard disks instead of tape. These billions of hard disks do one thing well -- they store changing digital information in a relatively permanent form. They give computers the ability to remember things when the power goes out.
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In this article, we'll take apart a hard disk so that you can see what's inside, and also discuss how they organize the gigabytes of information they hold in files!
Computer Hardware - Learn all the basics
hard drive
In order to use it, you will need to have it recognized by your PC/LAPTOP and/or format it by following the steps below: (Your drive should be automatically recognized by your Windows O/S
but in some rare case, you need to tell your PC/Laptop that it has a
new drive connected and what drive letter to use it :
CONTROL PANEL -> ADMISTRATIVE TOOLS
MANAGEMENT -> STORAGE -> DISK MANAGEMENT -> locate your 'slave' drive -> right click on the drive to bring up the
context menu -> if required, Create required partition(s) -> if
required, FORMAT partition(s) ->
'change drive letter and path' to assign a drive letter to your
partition(s) on your slave drive.
Hope it helps!
Lights on nobody home
my LaCie BigDisk has a blue light when I plug it in but nothing happens, can't hear or feel it whirring. Can it be fixed? How?
It was ok testerday but
Unfortunately, I have tried to use the other cable that is able to give more power from the other connector that LaCie provides; and the computers are still not able to detect it. Any new advice?
Unfortunately, I have tried to use the other cable that is able to give more power from the other connector that LaCie provides; and the computers are still not able to detect it. Any new advice?
what kind of technician can do this job? I mean what type of shop I should look for?
My Lacie was working fine
My Lacie was working fine till I brutally unplugged it from usb port when I about to go home from office. After I go home, I plugged it to my home computer, it cannot be detected any more. Next day I brought it back to office and tried on multiple computers, none of them can detect it even thought all the computers can detect other device plugged in the same usb ports. I have also use the other usb cable provided by LaCie that is able to plug into the other power-like connector on LaCie's end and usb connector on the computer's end. This way still cannot make it be detected.
Comments:
Mine is not hard disk but external hard drive. I have tried different different cables from different connection point of the external hard drive. If the first connection point of the cable is broken, the second cable connection should not have issue, isn't it? If you insist it is the cause and solution, then what type of shop should I look for? What type of technician should I ask?
head unit
The control center and user interface for an automobile's entertainment center, which typically resides in the center of the dashboard. It provides the main controls for the radios (any combination of AM, FM, XM, Sirius, HD Radio) as well as a CD/DVD player, GPS navigation, Bluetooth cellphone integration, hard disk storage for music and iPod connector. There may be auxiliary controls on the steering wheel.
Self Contained
The head units have their own amplifiers for powering the speakers, but may have optional outputs for more powerful, stand-alone amplifiers. After market products typically have the most flexibility, although head units in luxury cars have very elaborate audio systems
head skew
The offset distance from the start of the previous track so that the head has time to switch from top of platter to bottom of platter and be at the start of the new track.
head mounted display
Styles Top Quality www.ZenniOptical.com
A display system built and worn like goggles that gives the illusion of a floating monitor in front of the user's face. The head mounted display (HMD) is a critical component of a body-worn computer (wearable computer). Single-eye units are used to display hands-free instructional material, and dual-eye, stereoscopic units are used for virtual reality applications
Head crash computer definition
The physical destruction of a hard disk. Misalignment or contamination with dust can cause the read/write head to collide with the disk's recording surface. The data are destroyed, and both the disk platter and head have to be replaced.
The read/write head touches the surface of a floppy disk, but on a hard disk, it hovers above its surface at a distance that is 5,000 times smaller than the diameter of a human hair. It has been said that the read/write head flying over the disk surface is like trying to fly a jet plane six inches above the earth's surface.
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