Basic concepts of Assembler language , Basic Computer Science

Information Units
In order for the PC to process information, it is essential that this information be in unique cells called registers. The registers are sets of 8 or 16 flip-flops.
A flip-flop is a device able of storing two levels of voltage, a low one, regularly 0.5 volts, and another one, usually of 5 volts. The low level of energy in the flip-flop is interpreted as off or 0 and the high level as on or 1. These states are typically known as bits, which are the littlest information unit in a computer.
A group of 16 bits is identified as word; a word can be separated in groups of 8 bits called bytes, and the sets of 4 bits are called nibbles.
Numeric systems
The numeric system we use every day is the decimal system, but this system is not suitable for machines since the information is griped codified in the shape of on or off bits; this way of codifying takes us to the requirement of knowing the positional calculation which will permit us to express a number in any base where we want it.
Converting binary numbers to decimals
When we are doing effort with assembly language we come on the need of converting numbers from the binary system, which is used by computers, to the decimal system used by people.
The binary system is supported on only two conditions or states, be it on (1) or off (0), consequently its base is two.
Converting decimal numbers to binary
There are a number of methods to convert decimal numbers to binary; only one will be analyzed here. Logically a conversion with a scientific calculator is much simpler, but one cannot always count with one, so it is suitable to at least know one formula to do it.
The technique that will be clarified uses the successive division of two, keeping the remains as a binary digit and the result as the next number to divide.
Hexadecimal system
In the hexadecimal base we have 16 digits which go from 0 to 9 and from the letter A to the F; these letters stand for the numbers from 10 to 15. therefore we count 0,1,2,3,4,5,6,7,8,9,A,B,C,D,E, and F.
The exchange among binary and hexadecimal numbers is simple. The first thing done to do a exchange of a binary number to a hexadecimal is to divide it in groups of 4 bits, beginning from the right to the left. In case the last set, the one most to the left, is less than 4 bits, the missing places are filled with zeros.
BCD Method
BCD stands for acronym of Binary Coded Decimal. In this information groups of 4 bits are used to stand for each decimal digit from 0 to 9. With this technique we can stand for two digits per byte of information.
Floating point representation
This depiction is based on scientific notation; this is, to represent a number in two divisions: its base and its exponent.
As an illustration, the number 1234000, can be characterized as 1.123*10^6, in this last notation the exponent indicates to us the number of spaces that the decimal point must be moved to the right to get the innovative result.

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