Hardware Autopsy
the technique will enable a tenfold increase
in drive capacities over the next fi ve to seven
years: That translates to an areal density of
one terabit per square inch, compared with
today’s anticipated limit of 120 gigabits. Areal
densities that high would pave the way for 3.5-
inch drives capable of holding more than four
terabytes of data, 2.5-inch notebook drives
boasting 500GB capacities, and 1.0-inch
drives packing up to 60GB.
In preparation for the switch to this new
technology, drive manufacturers have been
experimenting to see just how far they can
take it; and the results so far have been prom-
ising. Seagate, for instance, has already dem-
onstrated a drive with an areal density of 245
gigabits per square inch and with read speeds
of 60MB/s—a tick faster than today’s fastest
7,200rpm drives, but with more than twice the
capacity. Hitachi, meanwhile, demonstrated a
prototype drive last March that delivered areal
density of 230Gbpsi. The company said it
expects to see one-terabyte 3.5-inch desktop
drives and 20GB Microdrives rolling off its
assembly lines sometime in 2007.WHAT’S NEXT?
Perpendicular recording will fend off the super-
paramagnetic effect for several more years,
but engineers around the world are hard at
work developing what they hope will prove to
be the next quantum leap in storage technol-
ogy beyond even that.
A hybrid technique known as heat-
assisted magnetic recording, for example,
envisions using a laser to create a hot spot
on the magnetic media while data is being
written. Heating the media reduces the
magnetic fi eld required to write to it; the
subsequent rapid cooling stabilizes the data
that’s been written. Heat-assisted recording
promises a dramatic increase in recording
density while simultaneously circumventing
the superparamagnetic effect.
Self-ordered magnetic arrays (SOMA)
are yet another approach to the problem: As
mentioned earlier, each bit of data consists
of about 100 grains of material. Scientists
are exploring the possibility of using an
array of iron-platinum particles to achieve
a bit-to-grain ratio of 1:1. This technology
would increase bit density by a factor of 100,
because each bit would be represented by a
single grain of material.
While perpendicular recording, heat-
assisted magnetic recording, and self-
ordered magnetic array technologies prom-
ise impressive advances to storage, the
superparamagnetic effect will continue to
present a barrier to progress as long as the
hard drive industry relies on electromagnetic
technology for data storage.r&dBREAKING DOWN TECH —PRESENT AND FUTURE
72 MA XIMUMPC DECEMBER 2005 DECEMBER 2005 MA XIMUMPC 73
White Paper: Perpendicular Recording
Technology
CULTISH LOGO
The iPod’s
emblematic shiny
silver backing
is also utilitar-
ian—great for
checking your
teeth for spinach
after dinner, or
as a reflector if
you’re stranded
in the desert and
need to signal
for help.POWER MANAGEMENT UNIT Philips
PCF50605HN Power Management
Unit is responsible for delivering juice
to any components that need it (par-
ticularly when the hard drive
spins up). It’s also a
housekeeper, turning
off the backlight if you
haven’t touched your
iPod in a while.HARD DRIVE
Toshiba’s 30GB,
4,200rpm
MK3006GAL
stores all 30
gigs on a single
disc platter aug-
mented by a 2MB
cache.CPU Motherboard, CPU, audio decoder, image
decoder, display driver, and traffic cop are all rolled into
PortalPlayer’s PP5020, a single chip about the size of
a square M&M. All this processing muscle comes from
two ARM7 processors with 8KB of cache, plus 32MB of
SDRAM for caching music to minimize hard drive use.DIGITAL SIGNAL
PROCESSOR The Wolfson
WM8975 digital signal
processor is the tooth-
some voice of the iPod. It
converts digital data from
the MP3/AAC decoder into
the analog audio that’s sent
to your headphones. It’s
also the home of the iPod’s
EQ presets, the headphone
driver, and a noise gate
that minimize electrical hum
from the activity of the logic
board’s integrated circuits.
Guess what? Support for
LITHIUM-ION BATTERY The lithium- WMA files is built-in!
ion battery in today’s iPods replaces
the thin, moldable lithium-polymer that
performed so poorly in the original
design. You can squeeze more than
16 hours of playback from it if you
keep the backlight off and don’t con-
stantly change tracks (which requires
the hard drive to spin up again).iPod Photo
Dual-core processors, WMA support, and other secrets of the fourth-generation
Photo iPodHEADPHONE JACK
The headphone/
remot e-control jack
attaches to the main
logic board via the
gold-colored ribbon.