I was never a fan for electricity and magnetism while circuits and stuff isn't exciting to me. I could share with students how statistical physics and the little magnetic moments that have contributed to the solid state devices we rely on, such as mp3 players, but I think I would bore them to death with this. Still I got to teach them to my students. So here's what I did


Why do we need wires when all the connections are etched on these circuit boards now?


Capacitor of my never used again PCI to 4 x USB 2.0 ports device


Side view of the PCI card


The processor for the device, I guess, made in Taiwan too


Hard disk surface


The tiny head that reads the 'magnetic' information off the hard disk drive

Note, don't do this (dismantle your hard disk) at home as this will void the warranty and may result in critical damage to your devices. My was spoilt in the first place.

All photos taken with the Sony H1 together with the M3358 close up lense. See all the dust on my PCI card?! LOL


Warning, Physics related stuff ahead, read at your own risk

My spoilt hard disk was a 5 year old 40gb Maxtor hard disk. Assuming that the disk space are evenly distributed over the 4 cylinderical disk (I see multiple layers). We have 10gb per layer. I estimate that the area of a layer is about 200 cm^2. Taking 10gb = 10,000,000,000 bytes, we have about 1 byte of information per 2 square micron area. Or 1 byte in a 1.4 x 1.4 micron space. (Or a strand of hair about 10 cm long can hold a wallpaper image of about 40kilobyte). If we look at per bit, that's about 500nm length per bit or over 1000 atoms wide and unknown atoms thick.

How much further down can we go before we hit the quantum limits? How much smaller can the hard disk read/write head could be (to squeeze in more layers)? Maybe we will be hitting the limits at terabyte level. Until quantum computers come by that is, only then we could work at the atomic level.

Ah well, hope my students will find this interesting.

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