How Was 1 Kilobit of Memory Over 50 Years Ago?

As someone who once paid $80 for 8 megabytes of RAM, I know those stories about expensive, limited memory. But those stories are barely twenty or thirty years old. If we go further back, between 1955 and 1975, memory was not only extremely rare and costly, but its construction had a profile we could describe as "artisanal" if you will. Ladies and gentlemen, meet magnetic core memory.

What can you do with 125 bytes? These days, probably not even enough to send an SMS, let alone an email. In fact, what I just wrote before the period sums to 130 characters (including spaces, periods, and commas), a detail that helps us visualize how little information that really is. However, in those years, with a Cold War freezing the world, and both Elvis and the Beatles setting hearts on fire, computer experts squeezed every byte they could from their systems.

A New Era for Memory

Demands were increasing, and existing technologies began to show their first cracks, among them magnetic drum memory developed in the 1930s. The time had come for something new, and it was in the mid-1950s that magnetic core memory emerged.

The image above corresponds to a memory module with a total of 1 kilobit, exactly 125 bytes. Each of the toroids "trapped" between the copper wires represented a bit, and according to the direction of magnetization in those toroids, it was possible to identify zeros and ones. A critical aspect of this process lay in the order and position of the copper wires. By sending pulses of electric current through one wire or another, the system could modify the magnetization in a toroid, and by extension, its memory value.

Now, magnetic core memory had two additional characteristics. The first is that its reading was destructive. In other words, a bit that was in 0 was not affected, but reading a 1 caused a flip in the bit changing it to 0, and it had to be recreated. The second is that unlike modern RAM, magnetic core memory was not volatile, and could retain its last state even with a power interruption.

The superiority of magnetic core memory was quickly demonstrated despite several legal conflicts (almost a decade of lawsuits and counterclaims), and within twenty years, it managed to reduce its cost from one dollar per bit to one cent per bit. Improvements in the manufacturing process allowed a notable increase in density and miniaturization of the modules, but beyond the benefits, its fate was sealed when Intel pulverized the market with the first commercial DRAM memory, known as the Intel 1103. That is another story...

Source: