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--- glossary:glossary_a [2019/09/09 09:34] – Bob Vetterlein
+++ glossary:glossary_a [2019/09/10 07:42] – [Amps] Changed to a more useful answer. tgerbic
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 Address is the unique identification of anything. In the context of DCC it means the coding of each loco or other decoder, which ensures that it identifies the signals intended for it.
+You will encounter two address ranges in the NMRI DCC standard, two-digit addressing (called short addressing) and four-digit addressing (called long or extended addressing). The number of digits refers to how many hexadecimal digits are transmitted/received for a decoder address from the DCC system. A two-digit address can have hex numbers between 01 and FF (1 to 127 decimal). A four-digit address can have from 0001 to 27FF (1 to 10239 decimal). Many model railroad users use four-digit addressing in order to match up the DCC address with the four-digit train engine number to make it easy to remember the number to control the engine.  So, if the engine number is 1234, the train decoder will be set to 1234 as well. Generally address 00 is reserved in each number system for analogue operation and is also known as the Broadcast Address.
+DCC decoders store the addresses in Configuration Variables (CVs). Each decoder vendor may have different set of CVs to store the digits. Refer to the docs that came with your decoder.
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-===== Amps =====
+===== Amps or Ampere =====
+An ampere is a measure of current flow. It is roughly defined as 6.28 X 10^18 electrons passing a point in one second. From a formula perspective one amp equals one volt divided by one ohm. If you had a one volt battery connected across a one ohm resistor, you would expect to measure one amp of current flow around the circuit.  Current values are often shown in formulas and on datasheets with the letters “A”, mA or uA.  In formulas current is generally shown as the letter “I”. For example E = I x R.  The letter “I” would most often be a value in amps, milliamps or microamps.
+In the model railroad context, you would expect to see a DC supply or a DCC booster providing several amps of current to a track, and most other circuits  or LED signals using ones to hundreds of milliamps.
+In a home environment, you would expect to see outlets in the 13 amp to 20 amp range and mains breaker panels working in the 50 amp to 200 amp range.
-The unit of current. It is defined as the constant current which if maintained in two straight parallel conductors of infinite length, of negligible cross-section and placed one metre apart in vacuum, will produce between the conductors a force equal to 2×10-7newton per metre length.