This piece of computer history launched 1,500 tweets.
The man in the photo (my husband, Tim) is holding an IBM Type 706 Williams-Kilburn Tube Electrostatic Memory drawer that we found in my grandfather's pole barn. (What's a pole barn? Basically, a really big shed.)
Before I tweeted this photo, Tim and I did some rough, back-of-the-envelope calculations to guess how much memory this circa-1954 hunk of valve and metal contained.
We estimated, based on what my grandfather could remember from his days as an IBM salesman, that the memory drawer stored 4 kilobytes of data.
So we decided to look for more information on the IBM 706, which IBM built in the mid-'50s to serve as a modular memory component for the IBM 701 computer, otherwise known as "The Defense Calculator" (a creepily Cold War name for a computer intended for scientific calculations).
The IBM 706 contains two so-called Williams Tubes, each handling 1,024 bits of memory adding up to 2,048 bits--roughly one quarter of the 1,024 bytes it takes to add up to a single kilobyte. (There are 8 bits in each byte of memory, bringing the 706 to a mere 256 bytes.) In other words, we were optimistic about the 706's capacity. The crazy machine in the picture held only one-quarter of a kilobyte of memory.
It would actually take 2,768 IBM 706 units to store the 692KB of data in the photo from the tweet--enough to easily fill a large room or, say, a pole barn. To put another spin on it, it would take 2,097,152 of these IBM 706 drawers to equal the 512MB of RAM in an iPhone 4S. (The iPhone 4S also comes with a variety of Flash storage capacities, but that's a different kind of memory. Want to do some nerdy bit/byte/KB/MB calculating yourself? Here's how.)
I'm still struggling to wrap my mind around the rate of technological progress that got us from the Williams Tubes to phones with close to a GB of RAM in just under 60 years. Maybe we really will get flying cars sooner than later.
Updated to compare the 706's memory to RAM rather than Flash memory.