From: Don Maslin <donm(a)cts.com> this confuses the ideas of precision, accuracy and speed with complexity. Digital is absolute accuracy IE: 0101=5 and for a given machine any variation is error. Analog, is mushy on accuracy, 5 Volts at some output is "approximate". Digital to process data for a complex equation in real time has to collect it perform operations on it and output it. These occur at some rate that is fixed by hardware. The more complex the task the lower the total Throughput will be. Also there is latentcy, time from input to processed output, more complex means longer for a fixed speed. Analog, assuming a fixed slew rate for the op-amps used the system throughput IE: a change in input means near immediate change in output that will be complete in some "setteling time". That time even for slow op-amps is quite fast and usually in microseconds. Also analog does not mean the output cant be absolute (IF Vin or Fin exceeds N (some rate) then turn relay on). I've done some really neat things using pots realys and motors with only limited use of amplifying devices to trans late the pots output to something that can drive a motor. This is classic servo systems stuff and the fundemental circuit is the Wheatstone bridge for systems like this. If you add nonlinear devices like LOG taper pots(variable resistors) and gears and cams you can get reactions that can mimic things like non linear actions. The idea of balance is employed. This kind of automation was as common as flies and widely seen though often as simple devices. There is another group of machines that fall dead smack in the middle of the analog and the digital. These were the early preprocessing boxes that might take 8 channles of analog telemetry data and reduce it to stored data based on time, sensor and relative value or even as a histogram. While these machines would have counters, registers and some even core or drum(disk) they were at best not programable and most didn't even qualify as hardwired program (elementary state machine). Just a few points about early computer differences. Allison