  ```The theory of Digital System and Number System This part, I am going to describe about the digital system and number system, which are important for studying computer. Microcomputer or PC has its working as digital system that uses discrete numbers, especially binary numbers, such as counting number of population in Thailand or is used in computing and electronics, rather than a continuous spectrum of values (an analog system). The working of digital system is data-carrying signals carry either one of two electronic or the binary numeral system (base 2 numerals) represents numeric values using two symbols, typically 0 and 1 while our usual numbers, or numeral system we use a base ten system. This means that the value of each position in a numerical value can be represented by one of ten possible symbols: 0, 1, 2, 3, 4, 5, 6, 7, 8, or 9. So, in computing, computer will understand usual numbers or numeral system, if they could all be interpreted as the same binary numeric value in order to be processed. Afterward, computer will convert the binary numeric value to representation that people can understand. The series of letters and numbers in a form understandable and processible by a computer 1.Alphanumeric code Alphanumeric code is a series of letters and numbers which are written in an understandable form by a computer. Such alphanumeric codes are ASCII and EBCDIC 2.Numeric code It is a series that is used in computing that must be interpreted to the binary numeral system so that numeric code can be written in an understandable form. Typically 0 and 1 in the binary numeral system can be represented by any sequence of bits (binary digits), such as 101010102 has 8 bit. We may assume the binary numeral system (1 bit) as an electric wire in schematic that have the duty in transferring from one to another. In an electric wire or 1 bit will has value 0 and 1 There are information and symbols in the world, so the binary numeral system can be used instead of all alphabets. Consequently, the binary numeral system uses the larger group of bits in computing, for example, "Word" is a term for a slightly larger group of bits. A collection of bits is a byte, 8 bit = 1 byte, can represent one alphabet or symbol. Moreover, byte is the smallest unit of information storage, and Binary digits are almost always used as the basic unit of information storage and communication in digital computing. The unit of information storage 1,024 Byte = 1 Kilobyte (KB.) 1,048,576 Byte = 1 Megabyte (MB.) 1,073,741,824 Byte = 1 Gigabyte (GB.) 1,099,511,627,776 Byte = 1 Tera byte (TB.) A computer has an element, called "Bus" or the way to transfer data. Bus will have a data path that transfers data between computer components. In comparison, bus is road for communication. In working of bus, if a computer has the width of bus is 8 bits, a time (a second of time), data of transferring will has 1 byte (8 Bit = 1 Byte). Like, 16 Bit, 32 Bit and 64 Bit (2 Byte, 4 Byte and 8 Byte) When we have already known the unit of information storage, we should know about the speed of times, relate to frequency as well. For example, in 1 second can be transferred data about 1 byte, so 1 Hz means that an event repeats once per second. In fact, computer doesn't use 1 Hz in working, but computer use million of Hertz, such as the width of bus has 32 bits will have 100 MHz, it means 1 second = 4 byte. For More information, see the table below. The unit of frequency 1,000Hertz = 1 Kilohertz (KHz.) 1,000,000Hertz = 1 Megahertz(MHz.) 1,000,000,000Hertz = 1 Gigahertz (GHz.) 1,000,000,000,000Hertz = 1 Terahertz (THz.) I hope that you will understand more about Bit and Byte. Generally, you will see both words in the next part. For the next part, it is absolutely important for computer, it is "Central Processing Unit" (CPU) ```