什么是Computer Systems
计算机系统被定义为一种数字电子设备，可以对其进行编程以接受一些数据输入，然后根据程序指令处理这些数据，并以所需格式提供可用于某些有意义工作的输出。
计算机系统的特点
- 计算机系统是可编程的。
- 计算机接受原始数据并产生信息。
- 计算机系统是一台数字机器。
什么是Computer Program？
软件组件是计算机程序。该程序由一组指令组成，指导计算机系统的硬件组件执行所需的操作。
计算机程序一般使用高级（人类可读）编程语言编写，如C、C++、Java、Python等。
然而，高水平的程序首先需要转换为低水平（机器码）的二进制机器指令。二进制的机器指令可以直接被计算机解码和执行。这种转换被称为程序编译。
计算机系统对这些程序指令进行解释，然后执行所需的操作。CPU逐一执行程序指令。
计算机系统是一种数字机器
计算机是一种数字电子机器。这意味着，计算机可以理解和执行二进制的指令，二进制只由两个数字组成，即0和1。二进制代码也被称为机器码或机器语言。计算机中央处理单元（CPU）是计算机系统的大脑。CPU负责执行算术和逻辑运算。
然而，计算机的微处理器（CPU）只能解码和执行二进制机器码中的指令。因此，用哪种编程语言编写程序代码其实并不重要，因为最终，所有高水平的计算机程序都必须首先转换为二进制的低水平机器代码。机器指令只由二进制的0和1组成。也因此，所有高层次的程序都被转换为低层次的机器指令，可以直接由微处理器执行。
将高级程序转换为低级机器代码的转换过程称为程序编译。
Characteristics Of Computer System
The computers characteristics include automatic working, operating speed, accuracy of calculations, versatility, diligence, memory, program dependence and reliability of operational performance.
- Automatic Working.
- Operating Speed.
- Accuracy Of Calculation.
- Computer Is Versatile.
- Computer Is Diligent.
- Computer Has Memory.
- Computer Needs Program.
- Computer Is Reliable.
Components Of Computer System
The Computer system consist of four basic components Or Units . In terms of functionality , the computer system can be grouped in to four units .
The Computer System Components are :
- Input Devices ( Input Unit ) .
- CPU ( Central Processing Unit ) .
- System Memory ( Memory Unit ) .
- Output Devices ( Output Unit ) .
下面是一个计算机系统的理论代考案例：
(a) Consider the octal number 1234.
i) Write down the decimal value of this number
ii) Write down the hexadecimal representation of this number
b) Consider the decimal number –101.
Write down the representation of this number in each of the following binary representations.
i) 8-bit two’s complement
ii) 8-bit signed magnitude
iii) 9-bit ones’ complement
iv) 8-bit excess-127
Question 1.
(c) Write down (in hexadecimal) both the IEEE single-precision and double-precision floating-point representations of –37.375. Show your working.
(d) Consider the 8-bit two’s complement binary numbers 11100111 and 01111001. i) What is the result (in 8-bit binary) of adding these two numbers?
ii) What would be the values (0 or 1) of the V (overflow), C (carry), N(negative) and Z (zero) flags after the addition operation in (i) above? V: C: N: Z:
Question 2.
Question 3
- Draw the logic diagram for a 3-bit synchronous counter which counts in reverse binary number sequence (i.e. output values 7,6,5,4,3,2,1,0,7,6, …)
