University Computer Fundamentals Courseware-Chapter 1 Analysis of Computer Fundamentals
* We are most familiar with decimal data in daily life, but when dealing with computers, we will come into contact with binary, octal, and hexadecimal systems, but no matter which number system, the common thing is the carry notation system. Recognize the carry number system: If the number system used has R basic symbols, it is called the base R number system, R is called the "base number" of the number system, and the unit value corresponding to each fixed position in the number system is called "" right". The encoding of the carry notation system conforms to the rule of "carry every R", the weight of each bit is the power of R as the base, and a number can be expanded into a polynomial according to the weight. Refer to Section 1.2.2 in the teaching material to be familiar with the conversion operations and conversion methods between the above number systems. Decimal R=10, you can use 0,1,2,3,4,5,6,7,8,9 Binary R=2, you can use 0,1 Octal R=8, you can use 0,1,2,3 ,4,5,6,7 Hexadecimal R=16, you can use 0,...,9,A,B,C,D,E,F "Every R is advanced, borrow one as R" 1.2.1 Number Table 1.2 The Correspondence of Numerical Values between Different Hexadecimals B 3 11 3 3 12 1100 14 C 4 100 4 4 13 1101 15 D 5 101 5 5 14 1110 16 E 6 110 6 6 15 1111 17 F 7 111 7 1 7 16 10000 20 10 8 1000 21110 8 Decimal The specific rules for converting numbers into binary numbers are as follows: Divide by 2 and take the remainder until the quotient is 0; 1. Convert decimal to binary number 1.2.2 Convert between binary numbers 2. Convert binary number to decimal number 1.2. 2 Conversion between decimal numbers Converting decimal numbers to octal numbers and hexadecimal numbers is similar to converting to binary numbers. The specific rules are as follows: Divide by 8 (or 16) and take the remainder until the quotient is 0; the remainder taken first In the low order, the remainder is in the high order. 3. Convert decimal numbers to octal numbers and hexadecimal numbers 4. Convert octal numbers and hexadecimal numbers to decimal numbers Convert octal numbers and hexadecimal numbers to decimal numbers, just use 8 (or 16) as Cardinality, expand and sum by weight. 1.2.2 Conversion between various binary numbers? The method of converting binary numbers into octal numbers is as follows: from the low order to the high order in groups of 3 bits, if the high order is less than 3 bits, use 0 to make up 3 bits, and then expand each group according to the weight. and you can. ?The method of converting binary numbers into hexadecimal numbers is as follows: from low-order to high-order groups of four bits, if the high-order bits are less than four bits, use 0 to make up four bits, and then each group can be expanded and summed according to the weight. 5. Convert binary numbers into octal numbers and hexadecimal numbers 1.2.2 Convert between hexadecimal numbers 6. Convert octal numbers and hexadecimal numbers into binary numbers 1.2.2 Convert between hexadecimal numbers The method of converting octal numbers and hexadecimal numbers into binary numbers is to replace each digit of the octal number (or hexadecimal number) with the corresponding 3-bit (or 4-bit) binary number, then the upper three bits and the lower four bits can be replaced. Bits 010 011 100 101 110 111 0000 0 @ P , p 0001 ! 1 AQ aq 0010 " 2 BR br 0011 # 3 CS cs 0100 $ 4 DT dt 0101 % 5 EU eu 0110 & 6 FV fv 0111 ' 7 GW gw 1000 ( 8 HX hx 1001 ) 9 IY iy 1010 * : JZ jz 1011 + ; K [ k { 1100 , < L / l | 1101 - = M ] m } 1110 · > N ^ n ~ 1111 / ? O - o DEL 1.2. 3 Representation of non-numerical data 1. ASCII code 1 Input code The problem solved by the input code is how to use the Western standard keyboard to input Chinese characters into the computer. Input codes can be mainly divided into three categories: digital coding, pinyin coding and font coding. 2 GB code GB code is also called Chinese character exchange code, which is represented by two bytes, and the GB code of each Chinese character is unique. 1.2.3 Representation of non-numerical data 2. Chinese character encoding system 3 Internal code Chinese character internal code is a code used uniformly for storage, processing and transmission within equipment and information processing systems. No matter what input code is used, it is converted into an internal code immediately after entering the computer. What the inner code of 4 Chinese character font code Chinese characters represents is the exchange code of the uniqueness of Chinese characters, namely gives a name of Chinese characters, and how the appearance of this Chinese character is not within the inner code. Chinese characters have many strokes and different shapes, so it is necessary to give a shape for each Chinese character, which is generally represented by a dot matrix, which is the Chinese character model. 1.2.3 The representation of non-numerical data is the dot matrix shape of the word "ah" as shown in the figure. There are 16 × 16 squares in Figure 1.2, called 16 × 16 lattice, each square is represented by a binary code, with 1 for black dots and 0 for white dots. ? The relationship between various Chinese character codes is shown in the figure 1.2.4 Information units in computers Common information units in computers are: bit (bit), byte (Byte), word (Word), KB, MB