New kid on the block for hard drives, SATA, What is it? SATA stands for Serial
Advanced Technology Attachment.
Before I get to SATA we need to understand what IDE is and why
SATA is better.
Integrated Drive Electronics,
IDE, was introduced
in the early 1990's as a way to get around the built in drive tables in the bios
for computers; tables that every pc had. There is a limitation on the drive size
built into the tables, the limitation is calculated on: the number of heads, the
number of cylinders, and the number of tracks physically contained within the
drive. The maximum of all these parameters can only be
1024. There had to be a way to fool the bios when the drive is larger
than 30 meg. IDE does this by telling the controller that the drive is only 30
meg. This worked for a while, then when Intel introduced the 486 processor the
bios was rewritten to remove the drive tables from the bios and add the IDE
controller as a function. This removed the 1024 limitation and opened the door
for larger drives.
The IDE function is split into two distinct parts; the IDE interface, and the IDE
controller component. The interface is just that, a way to connect the drive to
the computer mother board. The controller is part of the drive, all functions
but one are integrated into the electronics of the drive. The one function that
is not built into the IDE controller is the drive selection. That originally was
a manual function, then became a part of the bios function. The selections were
master or slave, then came cable select. Cable select is by which connector on
the IDE cable the drive is connected to. By removing one wire from the cable to
the last connector the bios knows which drive is master and which drive is
slave.
As with all devices when they are new or just introduced they are the wiz bang
of the day. The speed of the IDE drives was phenomenal at
the time, SCSI was struggling to just keep up. Through put had quadrupled
over night. Drive size will reach beyond 200 gig. Reliability will reach a all
time high of over 200,000 hours between failures. This means that the average
hard drive will operate beyond the lifetime of the computer.
Your IDE drive is still a viable device, I would
not
throw away a perfectly good drive just to have the
latest and greatest. If the drive has failed or is to small then by all means
upgrade.
SATA, what is it? Why do I need it? Is it expensive?
Serial Advanced Technology Attachment or SATA:
Pros:
SATA uses the IDE controller concept on the haed drive to control the drives
functions. Using two pairs of signal wires the data-connection is
unidirectional. Utilizing Low Voltage Differential Signaling (LVDS) increase the
signal rate to a higher capacity of
1.5 to
3.0 gigabit per second.
The 8B/10B
encoding is 80% higher in efficiency than the
traditional parallel transfer encoding of the IDE interface. The 8B/10B encoding
is also used in the newer Ethernet, Fibre Channel, PCI Express, and other
devices. With the correct controller you can use a raid array to protect your
data.
Cons:
Only one device can be attached to a
cable. This means each device requires an interface connection and a cable.
(Since this article has been written the manufactures have been busy,
you can now get an interface that will support 16 32 devices!)
Rating:
I give the SATA device a rating of 9 out of 10, the reason is that each device
needs it's own cable and interface, when the manufactures get around to creating
a way to chain more than one device on a cable I will give it a 10 over all.
When technology moves forward you gain in functionality. With the SATA device
you gain an enormous speed in through put for your data, couple this with the
ever increasing capacity of hard drives and you are getting even more for your
hard earned dollar. If you have an older mother board you will have to purchase
a SATA controller card to go with the drive, the newer motherboards have
interface connectors built into them, along with the External SATA connectors
for external devices.
At this time the manufactures are working on a 6 gigabyte
per second devices.
Pricing:
Contrary to popular practices the SATA devices are cheaper than the older
devices, normally new technology devices cost twice to four times as much as
older technology. Such as a SATA drive that has twice the
capacity of an IDE drive at the same price.
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