William Case wrote: > Hi; I agree we are getting somewhat (or more) off the topic of the "on topic list ... William could you ask you question on the "main List"? where this is closer than SOME of the recent topics. > 1) a bit equals 1 or 0. More concretely, 1 is a pulse made up of 5+ > volts while 0 is really a pulse made up of approximately 3 volts. > In any case, is the above a fair description of what a bit is? Totally depends on the definition of the logic family you are using, The newer processors are using smaller voltages all the time, so they have the levels closer together. If you were using Silicon Bipolar transistors the threshold for a PN junction to conduct was 0.7 Volts. So that is probably a good place to set the difference from a 0 to a one in silicon based Logic. when the book you are using was written TTL was in vogue. It used a 5V supply, and "close to 5v" was one and less than 2 and a bit volts was zero. Before that their was "RTL Logic" which used very different levels. Google for TTL Logic, and 4000 CMOS One promising link from my search looks like Logic Voltage Thresholds for TTL, CMOS, LVCMOS, and GTLP IC's Switching Levels, Chart of voltage thresholds for TTL,CMOS, LVCMOS, GTL, BTL, ETL, and BiCMOS devices. Includes a table showing prefix and discriptions of ... www.interfacebus.com/voltage_threshold.html - 15k - Cached - Similar pages > By using varying doping levels and varying voltage levels > in a single transistor couldn't a trinary or a quadrinary, or a decimal > computer system be built. Putting aside why you might want to do that, > is there any physical restriction on why it can't be done.? Sure but them you logic gets scary, and you ability to separate noise from signal goes way down. > Lastly, as I look at various schematics of how a transistor works they > all seem to show that when there is a 0 bit the current, of course, is > too low of a voltage to complete the circuit. Those same schematics > show the low voltage being drained off to ground. Why isn't the low > voltage current used to form a separate low voltage path (circuit) so > that a transistor would be 'either', 'or' rather than 'on', 'off'. I am not sure what you are asking, the "other side" of the circuit is normally "ground". I think you are trying to have the transistor to have more states, and again that would only complicate the logic, as you would need MORE transistors, (or tubes, most of these logic ideas came from the time when Special 6sn7, and 12at7 Tubes were the logic ampliphiers.) I have recent snagged a copy of the GE Glow lamp Manual, where they did and and or gates and even adders using neon bulbs. which have two states, above 65 volts where they start to glow and below 55 Volts were the go out. if you keep them at 60 volts they will be in a state that depends on the last pulse you fed them.. (Eureka - Computer memory) Unless you want to design a computer from Scratch using discrete transistors (or Tubes or neon Lights) you should not try to worry about the electrons flowing, and if you do, then you have to worry about capacitance, inductance and the length of your signal part, (LOok up Admiral Grace Hopper and her "nanosecond Wire" -- Charles MacDonald cmacd [ at ] TelecomOttawa [ dot ] net Stittsville Ontario 1800+ Canadians oppose Bill C-60 which protects antiquated Recording, Motion Picture and "software manufacturing" industries from change... http://www.killbillc60.ca