4 ms·

My understanding is that all electronics are essentially analog, but we make them digital by assigning arbitrary thresholds digital meanings (e.g. everything <

My understanding is that all electronics are essentially analog, but we make them digital by assigning arbitrary thresholds digital meanings (e.g. everything < 5 is 0 and everything > 5 is a 1).

smoyer 10y ago
It's not that straight-forward ... the components in these analog computers have very specific characteristics over their operating range. Some may be very accurately linear, some may be logarithmic, etc. Digital components on the other hand are purposely non-linear in a way that causes the gates to be definitely a zero or a one. Some parts include Schmidt-Trigger inputs so that there is hysteresis when input signals might be noisy. One interesting fact about 4000-series CMOS parts - you can add a feedback resistor across an inverter and force the part into a narrow analog range. It's not good enough for audio or anything but you can make an RC oscillator, threshold detector, etc.
- smogcutter 10y ago
  Not "good enough for audio" in the sense of being musically pleasant, but you can make a dead simple audible square wave oscillator out of a schmitt trigger inverter. Great project for kids or anyone getting started with a breadboard.
- smitherfield 10y ago
  So would a quantum computer be a form of analog computer, then?
  - asimpletune 10y ago
    Yes
    - Udik 10y ago
      I've seen this view come up before on HN, with the same degree of confidence. I don't know enough about QC to discuss it myself, but from a quick search it seems that QC are generally considered digital: http://cs.stackexchange.com/questions/22856/is-quantum-computer-analog http://cs.stackexchange.com/questions/22856/is-quantum-compu... https://www.reddit.com/r/askscience/comments/20xnwc/are_quantum_computers_analog/ https://www.reddit.com/r/askscience/comments/20xnwc/are_quan... http://www.scottaaronson.com/democritus/lec14.html http://www.scottaaronson.com/democritus/lec14.html

My understanding is that all electronics are essentially analog, but we make them digital by assigning arbitrary thresholds digital meanings (e.g. everything < 5 is 0 and everything > 5 is a 1).

smoyer 10y ago

It's not that straight-forward ... the components in these analog computers have very specific characteristics over their operating range. Some may be very accurately linear, some may be logarithmic, etc. Digital components on the other hand are purposely non-linear in a way that causes the gates to be definitely a zero or a one. Some parts include Schmidt-Trigger inputs so that there is hysteresis when input signals might be noisy. One interesting fact about 4000-series CMOS parts - you can add a feedback resistor across an inverter and force the part into a narrow analog range. It's not good enough for audio or anything but you can make an RC oscillator, threshold detector, etc.

smogcutter 10y ago
Not "good enough for audio" in the sense of being musically pleasant, but you can make a dead simple audible square wave oscillator out of a schmitt trigger inverter. Great project for kids or anyone getting started with a breadboard.
smitherfield 10y ago
So would a quantum computer be a form of analog computer, then?
- asimpletune 10y ago
  Yes
  - Udik 10y ago
    I've seen this view come up before on HN, with the same degree of confidence. I don't know enough about QC to discuss it myself, but from a quick search it seems that QC are generally considered digital: http://cs.stackexchange.com/questions/22856/is-quantum-computer-analog http://cs.stackexchange.com/questions/22856/is-quantum-compu... https://www.reddit.com/r/askscience/comments/20xnwc/are_quantum_computers_analog/ https://www.reddit.com/r/askscience/comments/20xnwc/are_quan... http://www.scottaaronson.com/democritus/lec14.html http://www.scottaaronson.com/democritus/lec14.html