I saw a post on Reddit earlier comparing a computer hard drive from the seventies with one from more recently. Whenever I see these, I always think of the old 5MB drive IBM built in the 50s. It gives me great respect for the 32/64GB MicroSD cards that we have today for a comparative few dollars and are about the size of my thumbnail.

So I decided to do some math.

A 5MB drive at $10k per MB works out at $50,000.

I can buy a 4TB drive on Newegg for $300.

That’s 800 times more storage, for less than 1% (0.6% to be more accurate) of the cost in just over 50 years. And I can carry several of them at once.

In fact, now I’m curious. Let’s do this from a few angles.

Compared by mass:

According to Western Digital, their 4TB drive weighs 1.72lb. According to Wikipedia, the IBM RAMAC 350 weighed in at 2,140lb. So the RAMAC weighed the same as just over 1244 4TB drives. So in the same mass as the RAMAC (ignoring dimensions for this exercise), you could store nearly 5PB (4976TB?) of data, at a cost of $373,200, although I suspect that you’d get a volume discount if you bought that many drives.

Compared by price:

Back to the same numbers as earlier, the old drive cost around $50,000. At $300 per drive, I could buy approximately 166 drives for a total of over 660TB of storage. That means per dollar, our cost of storage has improved to somewhere in the ratio of 132800000:1, if my math is even close to right..

Compared by physical size:

According to Wikipedia again, the 350 was 60″×68″×29″. The 4TB drive is (rounding down to 1 SF) 1″x5.8″x4″ So let’s pick a direction and go with it. What do you know, 29 divides evenly by 5.8, so there are 5 in that direction. 68 divides by 4 to the order of 17 times, and 60 divides by 1 for a result of 60. So 60x5x17=5100. 5100 drives in the same physical volume of space. Forgetting our need for cabling, that would give us storage of over 20PB of data. Having cost $1.5 million.

Purpose for these numbers? None whatsoever. I was just curious to compare more than just the obvious size differences. Maybe I’ll get bored enough and calculate the same for MicroSD cards. I’ll leave you to ponder the numbers while praying I find something better to do with my time!