I don't often do this, so forgive me if you will.  But if you're about to pop down to your local computer shop this weekend and hand over around $150 for a terabyte of hard disk, this fascinating Youtube video will make you realise just how far we've come in the last half-century.

The video, which lasts 11 minutes, is a promotional film from IBM which dates from 1956, explaining how and why it researched and developed a device called the RAMAC.  It's the world's first hard disk, and was capable of storing a massive 5 megabytes of data in a device no larger than a refrigerator.  

I wonder what the people in this film would make of a 32 GB micro-SD card.  

http://www.youtube.com/watch?v=CVIKk7mBELI&feature=related