spinning platters


How did we get computers to have a “memory”? I mean, if computers are just made up of chips of metal and electricity, how can they store information?

Asked by anonymous


Computers have been around for quite some time– perhaps not in the way we typically think of them, but they have been there. At first, it was easy to conceive a mechanical way to store information, the problem came when we began demanding more out of computers, switching into electronic and magnetic components.

The main principle is storing information in one of two states: either 1 or 0. In terms of electrical components, this is simple: you either have a component in the “on” state or “off” state. The ways to process that information, save it, optimize the process, and make it fully automated vary immensely. 

Back in the good old days of computing, memory worked through purely mechanical means. How exactly did we achieve this? Well, one fairly well known method was using punched cards, or Hollerith cards. These were pieces of stiff paper with holes in them. This holes were punched in predefined positions, allowing for early computers– and I mean 1800s computers, not your grandma’s computers– to be able to process data and run automated processes. Note how the concept is fundamentally the same as our system: you still have a set of two distinct states. Several other mechanical ways of accessing and storing information also arose during the early periods of computing, methods which included valves and gears, but these processes were still slow and tedious.

Eventually, we began to need faster, more efficient, and less bulky ways for storing and accessing information.

The first attempt was using electrical valves, which are basically circuits wired so that one valve can be turned on and the other one off. This posed several problems in terms of space efficiency and was incredibly expensive, not to mention highly inefficient in terms of energy consumption. Another concern was how to make these system “non-volatile”, so that you could restart your machine and still have your information there.

Another idea was to place a long tube of mercury with one end on a loudspeaker. Ideally, you would have waves travel through the tube and would be able to detect pulses at the end of the tube. The problem was that you had to constantly circulate these waves, and you could only detect the pulse for a very brief period, right when the wave was “bouncing back”.

Eventually, we got to the point where we managed to create “cores”, which are basically magnetic rings threaded on wires. Bits of information were stored using the direction of the magnetization of the cores. The first cores were huge– storing 1Mbyte required the space of a small car, but we got around to making them smaller and more efficient.

To further optimize our computers, we shifted from magnetized cores toward electronic components. Namely, we’re using transistor chains, which apply a precise voltage to the circuit to produce a pattern of 1’s and 0’s depending on whether or not the current is conducted.

Nowadays, chances are your computer has either a Hard Disk Drive (HDD) or a Solid State Drive (SSD). HDDs are the most common way of storing information on your average computer. The’re basically metal platters with a magnetic coating that stores your information. The platters are spinning rapidly in an enclosed space from which a read/write arm accesses the data. SSDs are a bit more of a novelty for your average PC user, but are faster and more reliable. Instead of having your data stored in a magnetic coating, data in a SSD is stored in an interconnected flash memory chip, much like your USB. Since they do not rely on magnetic coatings, nor do they depend on mechanical parts (like moving arms), SSDs are more reliable and faster, but the drawback is that they are, at least for now, more expensive than HDDs.

In the end, the history of computers revolves around the same central theme: how do we make information readily available and easy to process? Over time, we’ve been demanding more and more out of our computers. As we do so, we of course face increasingly difficult challenges and are forced (or encouraged, if you like) to reinvent our ways in order to keep up with the demand for power and efficiency.

So how did we do it? We say: ingenuity, that’s how.

Answered by Demian L, Expert Leader.

Edited by Margaret G.