The slowest modem I ever had the pleasure of using was 9600 baud, but even at that rate, it was way too fast for me to actually comprehend that there was a seri

The slowest modem I ever had the pleasure of using was 9600 baud, but even at that rate, it was way too fast for me to actually comprehend that there was a series of high and low tones representing bits. Back in college, we had acoustically-coupled TDD devices at most payphones on campus - you'd pick up the handset, dial a number, and put it down on the coupler. Or you could just type on the coupler, and hear tones come out the speaker, at a blistering 45 baud. 45 baud is slow enough for your brain to process the different tones. If you run minimodem as `minimodem --tx tdd`, you can hear the same thing yourself today, without the coupler. Minus some further nifty hacks above 2400 baud, it was very convenient to think of modem breath as "the TDD tones, but much faster".