9月19日-计算机导论-课程内容（2）
9.19 2nd class content
Computer science major study content:
Data Storage
1,Binary and Hexadecimal
Bit:Binary Digit(0 or 1)
Bit patterns are used to represent information like numbers, text characters, images, sound and others.Because it is easy to design the circuit, to produce, to do arithmetic easily, accurately, quickly and it is reliable to work with.But people can’t read or write it easily, so when people write a number for the computer storage, they use Hexadecimal.
Each line of digital circuit is called one bit, for example, 64 bits CPU has 64 line, it can store 264-1 messages.
Carry count system has two point:
(1)has and only has corresponding numbers.
(2)meet the corresponding number then carry one.
2,Boolean Operations
An operation that manipulates one or more ture/false values.Also called as Logic Operations.
Actually computer can’t read the meaning of “+”, “-” and other things like that, it use Boolean Operations to represent it.
Specific operations:
- And:if two bit is 1 at the same time, output 1.
- Or:if some or other bit is 1,output 1.
- Xor(exclusive or):if two bit is different, output 1.
- Not:out put the contrary of bit.
3,Gates
Gate is a device that computes a Boolean operation.
- Often implemented as electronic circuits.
- Provide the building blocks from which computers are constructed.
- VLSI(Very Large Scale Integration)
4,Flip-flops
A circuit built from gates that can store one bit.
- One input line is used to set its stored value to 1.
- One input line is used to set its stored value to 0.
- While both input lines are 0,the most recently stored value is preserved.
5,Truth table
| A | B | A or（∨） B | A and（∧） B | A xor（⊕） B | not（┐） A |
|---|---|---|---|---|---|
| 0 | 0 | 0 | 0 | 0 | 0 |
| 0 | 1 | 1 | 0 | 1 | 1 |
| 1 | 0 | 1 | 0 | 1 | 0 |
| 1 | 1 | 1 | 1 | 0 | 0 |
1 is true,0 is false.
And “+ - * / ∨ ∧ ⊕ ┐” is called operator.
Vocabulary and Terminology
Bit 位
Binary 二进制的
Integer 整数
Fraction 浮点数
Compression 压缩
Manipulate 操作
Circuit 电路
Implement 工具
Integration 集成