Thursday, 11 September 2008

Hard Drives

Take a look at a hard disk from a top of the line computer, and an old fashioned video tape cassette. You can get TV and video programmes on the disk on in an instantly retrievable digital format, whereas with the tape, which is analogue, you have to hold down a button and fast forward through metres and metres of fragile tape to get to the next programme.
But which one of these is older?
It is the hard disk, invented in the mid 1950s. The magnetic tape in the cassette pre dates the hard disk by a few decades but you know what I mean… the hard disc has gone from strength to strength.
This week we are going to look at the latest incarnation of the hard disk, which has one terabyte (1,000 gigabytes) called Sata (Serial advanced technology attachment).

Your old discs
The old version, the IDE drive, is now known as a Pata drive (Parallel advanced technology attachment).
Let's look at some of the differences between Sata and IDE:
  • Sata is four or five times faster than an IDE drive
  • With Sata, if you have the right drivers (AHCI) inside your PC, they become "hot swappable", just like USB and Firewire. (Hot swappable means you can take the disk out while the computer is still running).
  • There is only one driver per cable
  • The cable is much thinner so possibly better for the airflow inside a PC
  • There are no more jumper settings
  • You need a new PCI card, or better still, a new motherboard to handle Sata
  • These have different power and data cables, but a simple adaptor can change from a Molex to Sata connector. Many adaptors can cause connection problems, and most new good PSUs now come with Sata connectors as standard.
  • There is a Sata cable which can supply power and data.

The future
I think it is really fascinating quite how far we have come. The hard disk has outlasted VHS tape, compact cassette, even little floppy disks.
What is good about the HD to make it last so long? It is proven, it is cheap and the capacity keeps on increasing. But it takes a lot of power, relies on moving parts and is very sensitive to vibration and shock.
The first hard drive was IBM Ramac, invented in 1956. It was the size of a large fridge, and the 50 spinning disks inside could hold an incredible (at the time) five megabytes.
And now we have a drive that holds one terabyte. About the size of a toaster.

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