By Chris Long
Reporter, BBC Click Online
From the world's first five-megabyte hard drive, to one which can store 400 gigabytes on 3.5 inches, computer storage has come a long way since the 1950s.
The hard disk is the storage bin of our PC - on it we keep our secrets, accounts, love letters, future plans, shopping lists and anything else you could imagine.
Hard disks have evolved hugely over the last few decades
If there is one thing we do well it is generating data. Lots of it.
These days disks are everywhere, although it has taken a while to achieve this ubiquity.
As soon as there were computers there was a need to keep data in a computer-friendly format. Names, addresses, dates and times all have to be stored in a way for the computer to find them.
It started off with punch cards, which actually predated the computer.
Holes were punched into cards which could be read by more or less any computer, but before too long it became apparent that something more was needed.
In the mid 1950s IBM developed the first hard disk, which started us on the track we are on now.
The IBM PC helped transform hard disk technology
Despite being the size of several wardrobes and sporting a storage capacity of five megabytes, it was soon the must-have peripheral for all computer systems.
Over the years they have grown in capacity and shrunk in size.
Probably the most important stage in the hard disks development was the IBM PC.
In 1983 IBM introduced the 10 megabyte hard disk to its users and we have been generating junk in our PCs ever since.
Robin Varley, of Samsung, says: "When PCs first entered the workplace they had a very small hard disk drive capacity but a very large hard disk drive."
Guy Weavers, of Seagate, adds: "When I joined the industry in 1984 we were dealing with five or 10 megabyte drives. They were 5.25 inch form factor, which means the disks themselves were 5.25 inches in diameter.
"That particular size of drive grew over the years - five, 10, 20, 40, 100 and so forth - and that was the first form factor to exceed the one gigabyte, or 1,000 megabyte, capacity point."
To give you an idea of how far we have come you can now get a 400 gigabyte hard drive that is just 3.5 inches in diameter
Robin Varley says: "Over the last few years we've seen a lot of development with regard to the size, the capacity, and the requirement to store more information to our computer."
To give you an idea of how far we have come you can now get a 400 gigabyte hard drive that is just 3.5 inches in diameter. That is 400,000 megabytes.
Guy Weavers says: "We have to increase the ability of the drive to store data, we have to increase the number of bits we can get on a track, and we have to increase the number of tracks we can get per inch.
"That involves technology increases in both the disk itself, the media we record to, and also the heads that we use to read and write the data."
The tracks are like invisible circles on the disk, and the data is written on them.
The smaller the tracks, the more data can be written.
There are now so many hard disks that there is no longer room to put them in our computers, so we now put them in boxes that sit next to our computers.
Hard drives are rapidly getting smaller and smaller
Now we are looking at drives that are one inch big, or perhaps even less, at 0.85 of an inch.
In fact it is fair to say that most hard disk manufacturers are moving development from the traditional desktop 3.5 inch and notebook-sized 2.5 inch disks, to the smaller drives.
It is in part the iPod's fault, as Nick Spittle, of Toshiba, explains.
"We had a 1.8 inch drive technologically available for some time before an application came along to utilise it. Apple's iPod was obviously a very good application."
Guy Weavers adds: "As well as increased capacity we continue to reduce the size. I think where we'll go is higher capacity on the smaller form factors."
And it will not stop there. Tiny hard disk MP3 players are on their way and there should be mobile phones with a disk in them before the end of the year.
PDAs will follow after that, then it is anyone's guess.
The bottom line is: if it is big enough to hold one, then it could well have a hard disk in it.
Click Online is broadcast on BBC News 24: Saturday at 2030, Sunday at 0430 and 1630, and on Monday at 0030. A short version is also shown on BBC Two: Saturday at 0645 and BBC One: Sunday at 0730 . Also BBC World.