Back in the olden days when computers were both analog as well as digital, making RAM was really extremely hard. Without transistors, the only purely electronic indicates of building a memory system was vacuum tubes; It might have been done, however for any type of appreciable amount of RAM indicates an outrageous amount of tubes, power, as well as high failure rates.
One of the options for early RAM was something called a delay line. This gadget utilized ultrasonic transducers to send a pulse with a medium (usually mercury filled tubes heated to 40°C) as well as reads it out at the other end. the time between the pulse being sent as well as got is just sufficient to serve as a extremely large, little capability RAM.
Heated tubes full of numerous pounds of mercury isn’t something you’d want sitting around for a basic electronics project. You can, however, develop one out of a Radio Shack electronics discovering Lab, a speaker, as well as a microphone.
[Joe] created his delay line utilizing an op-amp to amplify the train of acoustic pulses traveling with the air. A compactor picks up these pulses as well as sends them into a flip-flop. A decade counter as well as oscillator supply the timing of the pulses as well as a method to put each bit in the delay line. When a button on the electronics lab is pressed, a ‘tick’ is sent into the speaker where it travels across [Joe]’s basement, into the microphone, as well as back into the circuit.
The entire configuration is able to store ten bits of info in the air, with the data easily pictured on an oscilloscope. It’s not a functional method to store data in any type of way, shape, or form, however it is an fascinating peek into the world before digital everything.
Video below.