Digital Memory's Evolution

A recent search for "largest capacity thumbdrive" revealed a one-terabyte drive from Kingston. That post was in January of this year, so certainly things have increased since then. Based on a wild guess as to the dimensions, I'm going to say this drive measures one inch by half an inch by two inches if you don't count the connectors. So one terabyte is packed into one square inch. Since one byte (in this context) is equal to eight bits, that's 8 trillion pieces of information in a little space. Break it down even further, and each tiny piece of information takes up 1.25 x 10^-13 square inches. Wow.

That got me thinking. In 1989 or so, our family's first computer had around 100 megabytes of HDD space, which seemed pretty good at the time. It also had a turbo button that took it from eight megahertz to 16 megahertz -- I still have no idea why it was used. Roughly 25 years later, a tiny thumb drive contains 10,000 times the amount of information that my first computer could store.

My family's 1989 computer might seem like primitive technology compared to today's extreme memory density, but let's not forget what came before. Thirty-five years before this rather arbitrary date, in 1954, the IBM 704, the first computer that could handle floating point arithmetic, came to market. This beast, used to handle the US Strategic Air Command (SAC), could store 3.75 megabytes of information per reel of tape and had 18.4 megabytes of core storage capacity, which it used as RAM. Interestingly, this computer's random access memory was allocated in 4,096 36-bit words.

A colleague mentioned to me that flip flops were used as memory (I'm not certain if it was the same core storage) in the SAC. The military seems to love acronyms even more than industry. These flip flops were described as being similar in configuration to a modern ice cube relay. Each module stored one bit of information. Engineers spent a lot of time optimizing these circuits on a bit level. These early memory modules were invented in 1918 by William Eccles and F.W. Jordan and used two vacuum tubes.

Of course, there were many, many steps in between the flip flop and a modern thumb drive. Old school nerds will certainly be familiar with data storage methods like punch cards. An earlier implementation of those cards could be considered to predate the flip flop, since they were used in player pianos.

I grew up in the 1980s, and it always seemed that we would have a moon colony by now -- or at the very least flying cars and a robotic maid. However, not many people envisioned a world where information would be this cheap or abundant. Also, most people didn't foresee sharing that information nearly instantly worldwide.

It's nice to step back and think about the progress that we as a society and as engineers have made over the years. There is certainly more to this story than I've written here. I'd love to hear your thoughts on the modern information and memory explosion.

— Jeremy Cook is a manufacturing engineer with 10 years experience and has a BSME from Clemson University. In his spare time he enjoys writing for DIYtripods.com.

I have an 8K core memory board hanging on my office wall, once belonging to a DEC something or another, just below a couple of (very old) Marconi Wireless Telegraph Company stock certificates. There was a story floating around Control Data's early days about its core memory and how the tiny magnetic donuts were hand threaded in Hong Kong because the process needed the fine and delicate hands of Asian women. The location was affectionately known as "Bill Norris' Far East Core House"!

My favorite historical memory device is the Univac FASTRAND moving head magnetic drum unit, which stored data on the surface of a heavy drum approx 6 feet long by 1 foot in diameter. The Devil's DP Dictionary defined it as "a device for storing angular momentum". The gyroscopic effect of the drum was so strong they had to add a counter-rotating drum so that the 4,500-pound unit wouldn't turn as the Earth rotated.

OK, I can beat you all. My first computer, a Sinclair ZX81 (used to be called Timex in the states) had just 1K of RAM.

I'll see your Sinclair and raise you by an Elf. I built my first computer based around the design for the RCA 1802 Cosmac Elf. It had 256 bytes of CMOS memory and that consisted of 2 chips! When I developed our first product I used a 1K x8 bipolar PROM that I turned on and off to conserve power, and after partioning the software functionality paged in ~200 bytes ar a time (needed scratchpad,stack etc in the rest).