In 2001, Apple introduced the iPod, an MP3 player with the unheard-of storage capacity of 5 gigabytes.
Five iPod generations later, the device plays songs, movies and photo
slideshows, and you can store up to 80 GB of any type of file you want.
The evolution has been a lesson in consumer electronics marketing and
development: Millions of people are so hooked on the iPod, they
continue to buy it and its coordinating Apple products despite quick
battery death and difficult repairs.
In this article, we'll find out why so many people buy iPod after iPod, dissect an iPod video to find out how it works and
check out what type of software is available to enhance its functionality.
The fifth-generation (5g) iPod video is much more than an MP3 player. It's a digital audio player, video player, photo viewer and portable hard drive, making it a full-fledged portable media center.
It's available in 30-GB and 80-GB capacities and has a 2.5-inch, color
LCD screen. In addition to the iPod 5G, the current generation of iPod
In this article, we'll be focusing on the top-of-the-line, fifth-generation iPod with audio and video capabilities.
the iPod is an Apple product, it works with both Mac and Windows
machines. Since it's the top-selling media player in the United States,
probably the big question is: What makes it different from any other
digital media player? The answer will differ depending on who you ask.
Some might say it's the form factor -- the 80-GB iPod video is just
over half an inch (1.4 cm) deep and weighs about 5.5 ounces (156
grams). For comparison, the iRiver PMC-140 (a Windows-based portable
media center) is 1.3 inches (3.3 cm) deep and weighs 9.6 ounces (272
grams), and it only holds 40 GB (but the screen is bigger at 3.5
Other people might tell you it's the Apple Click Wheel,
a touch-sensitive wheel that makes it incredibly easy to navigate
through the various menus and options with just a thumb. According to
Apple CEO Steve Jobs in a Newsweek interview,
"It was developed out of necessity for the Mini, because there wasn't
enough room [for the buttons]. But the minute we experienced it we just
thought, 'My God, why didn't we think of this sooner?'" And then, some
might tell you the greatest thing in the world is the super-tight
iPod/iTunes integration (which, ironically, others will curse until the
day they die).
is the integrated jukebox/media- player software that comes with an
iPod. It lives on your computer, and you use it for organizing,
playing, converting and downloading files from an external source to
your computer and from your computer to an iPod. This is really no
different from the software than comes with any other portable media
player. The thing that makes iTunes a brilliant invention from a
consumer-electronic s standpoint is the built-in iTunes Store that keeps iPod users coming back to Apple on a regular basis.
iTunes Store lets iPod users purchase music, movies, podcasts,
audiobooks and music videos with a click -- it's an integral part of
the iTunes software. The Store offers 3.5 million songs, tens of
thousands of podcasts, 3,000 music videos and 20,000 audiobooks, as
well as TV shows, feature films and iPod video games. You can watch or
listen to the files through iTunes on your computer and download them
to your iPod. And you don't even have to drag and drop: The iTunes
software autosyncs with iPod whenever it's connected to your computer through a USB 2.0 port (you can use FireWire
for charging, but not for syncing). Just plug it in, and the iPod
automatically downloads every new file that you added to your iTunes
jukebox since the last time it was connected. It also uploads to iTunes
all new data that you added to your iPod since last the two conversed,
like playlists and song ratings.
addition to the iTunes integration and autosync, the Click Wheel (more
on this in the hardware section) and the slim form factor, some of
iPod's more notable features include:
For a full list of iPod features, see Apple: iPod. Now let's get inside an iPod video to find out how what hardware it uses to accomplish these tasks.
we take apart our iPod video, there are a couple of things you should
know. First, the screen on this iPod is cracked. Since no one at
HowStuffWorks volunteered their perfect little iPod as a subject for
this author's screwdriver, we turned to eBay
to find a damaged unit we could take apart with good conscience. Which
brings us to the second thing you should know: iPods are almost as
valuable broken as they are in mint condition. After several
last-minute outbids, we found out we had to pay about $200 for a 30-GB
iPod video with a cracked LCD
-- this was the typical ending price for this type of unit. And a
brand-new, perfect one costs $299! We were left shaking our heads. Are
hundreds of people writing articles that incorporate an iPod
dissection? Are hundreds of people that addicted to tinkering
with high-priced electronics? Are iPods really so hard to get fixed by
Apple once the one-year warranty runs out? The New York Times article
"Good Luck With That Broken iPod" (February 4, 2006) would suggest the
latter, although it's really anybody's guess.
That said, let's pry this baby apart.
For most of the iPod video's functionality, we're dealing with seven primary components:
case actually isn't that difficult to get into -- we used a 6-inch
metal putty knife to pry apart the seam. Once you see that you need to
get the knife under the thin edge of one side of the casing (instead of
driving it straight down), it comes apart pretty quickly. Here's what
we saw when we pulled it apart:
This iPod video uses a 30-GB Toshiba 1.8-inch hard drive (model MK3008GAL),
featuring 4200 rpm and a USB interface. It weighs 1.7 ounces (48 grams)
and fits 30 GB onto a single platter, squeezing in 93.5 gigabits per
square inch. To fit so much into so little space, the drive uses
smaller and lighter sliders (which keep the right spacing between the
read/write heads and the recording surface) and a more sensitive
thin-film technology on the heads and the platter. The increased
sensitivity allows for a greater number of recorded bits per square
When you remove the front casing, you're looking at the LCD, the motherboard and the Click Wheel:
Click Wheel is a section unto itself, and we'll deal with that
technology on the next page. Let's start here with the iPod video
The display is a 2.5-inch, 16-bit, TFT LCD. It
has a 320x240-pixel resolution and a 0.156 dot pitch. The screen is
incredibly thin -- just 0.125 inches (3.175 mm) deep.
connectors used in the iPod are miniscule. Instead of the plastic
connectors you find in larger devices, the ends of the wires that
connect the various components of the iPod are coated in a film that
stiffens them to create a viable input. Here you can see where the LCD
connects to the back side of the motherboard (with a U.S. dime for
All of the chips and memory devices that make an iPod run are situated on the motherboard. Here's the front:
And here's the back:
the image above, you can see the Click Wheel controller. A
"mixed-signal array" is a chip that can deal with both analog and
digital data. In the case of the Click Wheel, the controller has to
accept analog data generated by the movement of a finger over the
surface of the wheel and turn it into digital data the microprocessor
can understand. Let's find out how it does that.
|The Click Wheel|
is a touch-sensitive ring that you use to navigate through all of
iPod's menus and control all of its features. It provides two ways to
input commands: by sliding your finger around the wheel and by pressing
buttons located under and in the middle of the wheel.
Under the plastic surface of the Click Wheel, there are four mechanical buttons (Menu, back, forward, play/pause), and there's one button in the center (select).
got five buttons and five corresponding contacts on the motherboard.
When you press, say, the right side of the wheel while you're listening
to a song, the wheel pushes down the forward button. The underside of
each rubber button is metal, so pressing it completes the corresponding
circuit on the motherboard. The motherboard tells the processor this
circuit is complete, and the processor tells the operating system to
fast-forward through the song.
Click Wheel's touch-sensitive function lets you move through lists,
adjust volume and fast forward through a song by moving your finger
around the stationary wheel. It works a lot like a laptop touchpad.
In fact, the company that supplied the Click Wheel for the 4G iPod was
Synaptics, most widely known for making laptop touchpads. For the 5G,
Apple created its own proprietary Click Wheel design based on the same capacitive sensing principle as the previous Synaptics-designed Click Wheel.
the plastic cover of the Click Wheel, there is a membrane embedded with
metallic channels. Where the channels intersect, a positional address
is created, like coordinates on a graph.
its most basic, a capacitive-sensing system works like this: The system
controller supplies an electrical current to the grid. The metal
channels that form the grid are conductors -- they conduct electricity.
When another conductor -- say, your finger -- gets close to the grid,
the current wants to flow to your finger to complete the circuit. But
there's a piece of nonconductive plastic in the way -- the Click Wheel
cover. So the charge builds up at the point of the grid that's closest
to your finger. This build-up of an electrical charge between two
conductors is called capacitance. The closer the two conductors are without touching, the greater the capacitance.
"sensing" part of the system comes in with the controller. The Click
Wheel controller (see above) is programmed to measure changes in
capacitance. The greater the change in capacitance at any given point,
the closer your finger must be to that point. When the controller
detects a certain change in capacitance, it sends a signal to the
microprocessor. As you move your finger around the wheel, the charge
build-up moves around the wheel with it. Every time the controller
senses capacitance at a given point, it sends a signal. That's how the
Click Wheel can detect speed of motion -- the faster you move your
finger around the wheel, the more compacted the stream of signals it
sends out. And as the microprocessor receives the signals, it performs
the corresponding action -- increasing the volume, for instance. When
your finger stops moving around the wheel, the controller stops
detecting changes in capacitance and stops sending signals, and the
microprocessor stops increasing the volume.
in discussing the workings of the Click Wheel, a particularly curious
HowStuffWorks staffer raised the following question: If your finger
controls the Click Wheel because your finger is a conductor, why can't
you control the Click Wheel with a paper clip?
While we scratched our heads, we embarked on a experiment.
Now that we've checked out the iPod hardware, let's take a look at the software it's supporting.
Photo courtesy Apple
iPod video main menu
iPod Hi-Fi system
Tavo iPod Gloves
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