基本概念
1.计算机入门
课文
1.1.1 Data and information（P1）
A computer is a machine whose function is to accept data and process them into information.
Data are facts or observations,while information is the meaning we attribute to them.
1.1.2 Data Processing （P2）
| Data | Input ------→ |
Computer
Process |
Output ------→ |
Information |
A computer is a data processing machine. Data flow into the machine as input.
Information flows from the machine as output.
The computer processes the data.
P2倒9
Often,data processing involves filtering and summarizing data so that underlying patterns can be perceived .
How does a computer process its data?
What functions,what operations,can it perform?
Generally,computers can add,sutract,multiply,divide,compare,copy,request input,and request output.
1.1.3 The Stored Program Concept（P3-10）
| Input | ------→ | Computer
Program |
------→ | Output |
If a computer is to function without direct human control ,it must be given a set of instructions to guide it, step by step,through a process.
The set of instructions is called a program.
The program is stored physically inside the machine,making it a stored program.
1.2 A computer System（P4）
| Processor | ||||
| | | | | |
||||
| Input Device |
------→ | Main memory |
------→ | Output Device |
| | | | | |
||||
| Secondary storage |
||||
System Components
A computer system consists of several basic components.
An input device provides data.
The data are stored in memory,which also holds a program.
Under control of that program the computer's processor manipulates the data,storing the results back into memory.
Finally,the results flow from the computer to an output device.
Additionally,most modern computers use secondary storage to extend memory capacity.
1.3 How a Computer Works（P5倒2）
| Processor | ||||
| | | | | |
||||
| Key board |
------→ | Main
memory Data→Program→Result |
------→ | Dis play |
| | | | | |
||||
| Diskette Drive | ||||
Memory's contents are easy to change.
Thus,when one set of data has been processed,the program can be repeated,reading and processing new data, and generating new output.
If the data can be changed,why not the program ?
When a program is finished,a new one can take its place in memory,allowing the computer to process completely different data.
关键字解释（P9）
1.Computer. A machine that processes data into information under control of a stored program.
计算机：在存储程序控制下把数据处理成信息的机器。
2.Input.Ttansferring data from an external device into a computer's main memory.
3.Memory.The computer component in which instructions and data are stored.
4.Output.The act of transferring data or information from the computer's main memory to an external device.
5.Processor.The component of a computer that selects and executes instructions.The processor contains a clock,an instruction control unit,an arithmetic and logic unit, and registers.
6.Computer program.A series of instructions that guides a computer through some process.
7.Stored program.A series of instructions placed in a computer's main memory to control that computer.
8.Data processing.Converting data into information.
词汇
| observation 观察结果
meaning 意义 attribute 解释 summary 综合 so that 以便 concept 概念 involve 包含 human 人的 guide 引导 pattern 模式、结构 underlye 基础 perceive 看出 filter 过滤 |
compoenent
部件，构件
storage 存储器 several 几个 consist 组成 provide 提供 additionally 另外、附加 modern 现代的、摩登 model 模型、模特 manipulate 操作 result 结果 finaly 最后、最终 content 内容 contrast 相反 device 设备 |
注释（P）
参考译文
1.1.1 数据和信息（P12）
计算机是一种能接收数据并把它处理成信息的机器。数据是事实或观察结果，而信息是人们对数据进行解释所得到某种意义。
1.1.2 数据处理（P13）
数据处理包含过滤和综合数据，以便看出数据的基础结构。
1.1.3 存储程序概念（P14）
如果一台计算机能在无人直接控制下运行，那么就必须给一组指令去引导它，使之逐步地通过一个处理过程。
1.2.1 系统的部件（P14）
数据存放在存储器内，存储器内还保存程序；在该程序的控制下计算机的处理器处理数据，把结果再存在存储器内。
1.3 计算机是如何工作的 ？（P15）
主存中的内容经常改变。当一组数据已被处理完后，而程序还可以重复使用，再读入和处理新的数据，并得到新的结果。如果数据能改变，当然程序也改变了。当一个程序运行完后，另一个新程序就占据了它在主存中的位置，让计算机去处理完全不同的数据。
2.处理器和主存储器
课文
2.3.3 Addressing Memory（P22倒7）
Each physical storage unit is assigned a unique address.
On most computers,the bytes or words are numbered sequentially-0,1,2,and so on.
The processor accesses a specific memory location by referencing its address.
For example, if the processor needs the data stored in byte 1048,it asks memory for the contents of byte 1048.
Since there is only one byte 1048,the processor gets the right data.
Depending on the computer, bytes or words are the basic addressable units of memory.
Data move between the processor and main memory a byte or a word at a time.
2.3.4 Reading and Writing Memory（P23-13）
The main memory of most computers is composed of random access memory,or RAM.
The programmer (through a program,of course)can read or write RAM.
Input data can be stored in RAM,destorying the old contents of the selected bytes or words.
Once the data are in,they can be read and manipulated by the processor,and results written to other memory locations.
Finally,the contents can be sent to an output device.
When a program is finished,a new program can be copied into RAM,erasing the old one in the process.
The contents of RAM are easy to change.
2.4 The Processor（P24倒1）
| Operation code | Operand |
| ADD | 1000,1002 |
The processor is controlled by a program.
A program consists of a series of instrctions.
Each instruction is a group of bits that tells the computer to perform one of its basic functions:add,subtract,multiply,divide,compare,copy,start input,or start output.
Each instruction consists of two parts,an operation code and one or more operands.
The operation code tells the computer what to do(for example,add,subtract,compare),and the operands identify the memory locations that will participate in the operation.
for example, the instruction in Fig.2.6 tells the computer to add the contents of memory locations 1000 and 1002.
The processor contains four key components:a clock,an instruction control unit ,an arithmetic and logic unit,and a set of registers.
The clock generates precisely timed pulses of current that synchronize the processor's other components.
The instruction control unit determines the location of the next instruction to be executed and fetches it from main memery.
The arithmetic and logic unit executes that instruction.
It consists of the circuits that add,subtrct,multiply,divide,compare,copy,and initiate input or output-the computer's instruction set.
Registers are temporary storage devices that hold control information,key data,and intermediate results.
关键字解释（P40）
1.Address.A location in memory.Often,the bytes or words that make up memory are numbered sequentially;the byte's(or word's)number is its address.
2.Instruction.One step in a program.Each instruction tells the computer to perform one of its basic functions.
3.Instruction set.The electronic circuits that add,subtract,multiply,devide,copy,compare,request input,and request output.On most computers,these are the circuits that make up the arithmetic and logic unit.
4.Machine cycle.The basic operating cycle of a processor during which a single instruction is fetched,interpreted,and executed.
5.Operand.The portion of an instruction that specifies the registers and/or memory locationa that are to participate in the operation.
6.Operation code.The portion of an instruction that specifies the operation to be performed;e.g.,add,subtract,etc.
7.RAM(random access memory).Memory that can be directly addressed,read,and written by the programmer.The main memory of a computer is generally RAM. Contrast with ROM.
8.Register.Temporary storage used to hold data,instructions,or control information in the prcessor.Often,the current instruction,the data being manipulated by that instruction,and key control information are stored in registers.
9.ROM(read-only memory).A type of memory that cannot be modified by the programmer.
词汇
| assign 分配
unique 唯一 unit 单元 access 访问 reference 参考 depend 取决 address 地址 addressed 寻址 addressable 可编址 story 储存 destory 擦除 erase 擦掉 generate 产生 precisely 准确 |
mediate 调停
mediane 中间 synchronize 同步 determine 决定 initiate 初始化 sequentially 顺序 execute 执行 during 在…期间 fetch 取出 interprete 解释 specific 指明 participate 参与 identify 标识、指明 |
注释（P）
参考译文（P48-5）
我们分配给每个物理存储单元唯一的一个地址。在大多数计算机上，字节或字按顺序编号，0、1、2等。处理器找到某一指定的地址编号后，即可访问该存储单元。 例如，如果处理器需要存放在字节地址编号为 1048 中的数据，它就从存储器取出 1048 号单元的内容。由于仅存在一个编号为 1048 的字节，处理器就得到了正确的数据。以字节还是以字作为存储器基本的可编址的单位，这取决于计算机，数据在处理器和主存之间每次只能传送一个字节或字。
P48倒10
大多数的计算机主存是由随机存储器或称 RAM 组成的。程序员（当然要通过程序）可读或写 RAM。输入的数据被存放在 RAM 中，此时破坏了被选中的字节或字的旧内容。一旦数据在主存储器中，数据就能被处理器读出和加工，并且把结果写入其它的存储单元。最后，把内容送给输出设备。当一个程序执行完后，一个新程序将被复制到 RAM 中，在复制过程中刷洗掉了旧程序。RAM 的内容易于改变。
P49-12
处理器是由程序控制的，程序是由一系列指令组成的。每条指令都是一组数位，这组数位告诉计算机完成它的一个基本功能，例如，加、减、乘、除、比较、复制、开始输入或开始输出的功能中的一个。每条指令由两部分组成，一个操作码和一个或多个操作数。操作码告诉计算机做什么，操作数指明存储地址，存储器的地址将参加运算，例如，在图 2.6 中的指令告诉计算机把存储地址 1000 和 1002 单元里的内容相加。
处理器由四个关键部件组成：时钟、指令控制单元，算术逻辑运算单元和一组寄存器。时钟产生精确的定时电流脉冲，使处理器的其它部件同步；指令控制单元决定了要被执行的下条指令的地址，并从主存中把指令取出；算术逻辑运算单元执行指令，它是由能完成加、减、乘、除、比较、复制、初始化输入/输出等计算机指令系统的电路组成的；寄存器是存储器件，它保存控制信息、关键字和中间结果。
3.输入和输出
课文
3.2.1 Keyboards and Display Screens（P52）
The basic input device on most small computer systems is a keyboard.
As characters are typed,they are stored in main memory,and then copied from memory to the basic output device,a display screen.
In effect,the screen,often called a monitor,serves as a window on main memory,allowing the user to view its contents.
3.3.1 Graphic Output（P53倒14）
The secret is to divide the screen into a grid of picture elements,or pixels.
Each pixel represents a dot or a point;by selectively turning the points on or off,a picture is formed.
The on/off state of each pixel is,essentially,binary,and can be stored in memory.
As memory is scanned,the picture elements are displayed,and the image appears.
3.5.1 Interfaces（P57倒15）
Consider,for example,a keyboard.
When a key in pressed,an electronic signal is sent to the keyboard's interface.
In response,the interface generates the code used to represent that character inside the computer,and transfers the coded data into main memory.
let's change the device to a printer.
As output begins,the data are store inside the computer as binary - coded characters.
The printer requires a dot pattern.
Clearly translation is necessary.
The coded characters are sent to the printer's interface, which translates the computer's binary codes to printer form.
The printer and the keyboard are different;the signals that physically control them and the electronic patterns they use to represent data are device - dependent.
However,because the device - dependent tasks are assigned to the respective interface boards,both can be attached to the same computer.
On input,an interface board translates external signals into a form acceptable to the computer.
Output signals are elecronically converted from the computer's internal code to a form acceptable to the peripheral device.
Because they are eletronically different ,a printer and a keyboard require different interface boards.
In fact,every input or output device needs a unique interface board to translate its device - dependent signals to (or from) the computer's internal code.
关键字解释（P62）
1.Buffer.Temporary storage used to compenssate for the different speeds of adjacent devices.
2.Graphics.computer output in the form of points,lines,and shapes.
3.Interface.On a small computer,an electronic component,often a board,that links an external device to a computer.More generally,an electronic component that link two different devices.
4.Keyboatd.An input device on which characters are repesented as discrete keys.When a key is pressed,the associated character is input to the computer system.
5.Pexel.A picture element.A spot on a display screen that can be selectively turned on or off.The basic unit of a graphic display.
词汇
| effect 结果
secret 秘诀、秘密 essentially 本质上讲 appear 出现 consider 考虑 code 代码 coded 编码 task 任务 attach 加上 physically 实际 respective 方面respectively 各自、分别 |
require 需要
patters 图形、结构 peripheral 外围 compensate 补偿 adjasent 邻接 character 字符 represente 表示 discrete 分离 associate 相应 spot 点 pixel 象素 picture element 象素 |
注释 （P65）
dot 实点
point 点的位置
参考译文
3.2.1 键盘和显示器（P66-9）
大多数小型计算机系统基本的输入设备是键盘。当键入字符时，字符就存入主存中，然后再把它从存储器复制到基本的输出设备—显示器。事实上，显示器通常称为监视器，作为主存的一个窗口，允许用户查看它的内容。
3.3.1 图形的输出（P67-7）
秘诀就在于把显示屏幕划分成图象元素网络，或称象素。每一个象素表示一个点的位置或一个实点。通过有选择地点亮或熄灭这些点，图象就形成了。每个象素的开关状态，本质上讲是二进制数，所以它们能被存放在主存中。当存储器的内容被扫描时，象素就被显示了，图象就出现了。
3.5.1 接口（P70-10）
以键盘为例，当键按下的时候，电子信号就送到了键盘的接口；响应该信号，接口产生了用来在计算机内部表示该字符的编码，并且把这个编码数据送给主存储器。现成来看打印机，当输出开始时，数据作为二进制编码的字符存在计算机内，打印机要求点阵的结构，显然是需要转换的，编码字符送到打印机的接口，接口把计算机二进制编码转换成打印机所规定的字符形式。
打印机和键盘是不同的，实际控制它们的信号和它们用来表示数据的电子信号的结构都是由设备决定的。然而，由于取决于任务的各种外围设备都有自己的接口板，因此键盘和打印机都可接同一台计算机上。在输入端，接口板把外部信号转换成计算机可接收的形式。输出信号从计算机的内部编码形式用电子设备转换成外围可接收的形式。由于打印机和键盘是不同的电子设备，所以它们要求不同的接口板。事实上，每个 I/O 设备都需要单独的接口板，把取决于设备的信号转换成计算机内部编码。
4.辅助存储器
课文
4.1 Why Secondary Storage?（P72-11）
Where exactly are the data and the programs stored ?
The obvious answer is main memory,but main memory is expensive,and the supply on most machines is limited.
Another problem is its volatility;main memory loses its contents when the power is cut.
We need a fast,accurate,inexpensive,high-capacity,nonvolatile extension of main memory,and secondary storage fills this need.
4.3 Accessing Secondary Storage（P77倒17）
How does the system determine where a particular program begins on disk?
Several sectors on the first track are normally set aside to hold an index or directory.
When the program is first written to disk,it is assigned a name,which is recorded in the index, along with the track and sector address where the program begins.
Latter,to retrieve the program,a user enters the program's name.The computer then reads the index,searches it for the name,finds the address where the program begins,and reads the program.
Data are accessed in much the same way.
The data for a given application are grouped to form a file;
we'll talk more about data files in Chapter 8.
Each file is assigned a name.
The file name and the address of its first sector are recorded in the disk's index.
Because the data that make up a file are normally stored in consecutive sectors ,knowing the first sector's address allows the system to find the others.
Secondary storage is an extession of main memory,not a replacement for it.
A computer cannot execute a program stored on disk unless it is first copied into main memory.
A computer cannot manipulate the data stored on a secondary medium until they have been copied into main memory.
Main memory holds the current program and the current data;
secondary storage is long - term storage.
The input and output devices described in Chapter 3 provide human access to the computer system.
Secondary storage does can be read and written only by the machine.
The only way people can access the data stored on a disk is by instructing the computer to read them into main memory and then output them to a display screen or a printer.
关键字解释（P）
1.Index.A list of the contents of a disk pack or other storage medium showing the locations of each file or program.
More generally,a value or set of values,such as an index register or a subscript,used to locate specific data.
索引：硬盘组或其它存储介质中内容的目录表，它指出每个文件或程序的地址。更常见的是用一个或一组值，例如一个索引寄存器或下标的值来寻找一个特定数据元素。
2.Sector.A fixed - length element of disk or other magnetic storage that holds a single physical record.
A common sector length on microcomputer systems is 512 characters.
扇区：磁盘或其它磁存储器中的一段固定长度的单元，它可以存一个单独的物理记录，在微型计算机系统上常用的扇区长度是512个字符。
词汇
| exactly 究竟、正是
exact 精密 obvious 显然、明显 expensive 昂贵 accurate 准确的 inexpensive 廉价的 nonvolatile 不易失的 answer 回答 aside 在旁边 |
set aside to
放在一边用于… along with 与…一道 direct 指引 index 索引 retrieve 寻找 consecutive 连续的 term 期限 convenient 简便 |
注释 （P）
参考译文
4.1 为什么要用辅助存储器？（P87-10）
数据和程序究竟存放在什么地方呢？显然是主存。但是，主存的价格很贵，所能提供的容量也很有限。另外，主存的易失性也是一个问题，当电源关掉时，主存就失去了它的内容。用户需要用快速的、精确的、廉价的、大容量的和不易失的存储器来扩展主存储器。辅助存储器满足了这一要求。
4.3 访问辅助存储器（P91-5）
系统如何确定一个特定的程序在磁盘的什么地方开始呢？第一磁道的若干扇区一般是用来放索引或目录的。当这个程序首次写到磁盘上时，要给它命名，该名字记录在索引中，并附有程序的起始点的磁道/扇区地址编号。当用户输入这个程序的名字，要寻找它时，计算机就读出索引，在索引中查找这个名字，找到程序起始地址，把程序从磁盘中取出来。
存取数据的方法与此相同。把给定的应用数据分成组，形成文件。在第8章中，我们将更多讨论数据文件。给每个文件命名，文件的名字和它的起始地址都记录在磁盘的索引中。由于组成文件的数据一般是在连续的区间存放的，因此知道了第一区的地址，系统就能找到其它区。
辅助存储器是对主存储器的扩展，但不能代替主存。除非先把一个程序从辅助存储器复制到主存中，否则计算机是不能执行存放在磁盘上的程序的。在数据被复制到主存中之前，计算机不能处理存放在辅助存储介质上的数据。主存储器保存的是当前要用的程序和数据，而辅助存储器则保存需要长期存储的程序和数据。第三章所描述的I/O设备为用户提供了一种访问计算机系统的工具，而辅助存储器则没有提供。数据以简便的形式存入计算机，并能被计算机读或写。用户能访问存储在磁盘上的数据的唯一的方法是向计算机发出命令，让计算机把数据取入主存，然后把数据输出，送给显示器或打印机。
5.部件的链接
参考译文 （P105）
5.1 微型机和大型机
5.1.1 总线和电缆
5.2 微机结构
6.操作系统
课文
6.2.1 The Command Language （P114倒11）
The programmer comunicates with the command processor through a command language.
Generally,there is a simple one-word command for each main function-LOAD (load a program from disk),
RUN(execute the program stored in main memory),
FORMAT(format a disk),DISKCOPY(copy a disk),and so on.
A user sitting at a keyboard types a command.
The characters flow from the keyboard,through an interface board,across a bus,and into main memory.
Once they're in memory,the command processor interprets the command and gives control to the appropriate functional module.
6.4.1 The Boot(P120-4)
Typically,the operating system is stored on disk.
The idea is to copy it into memory.
This objective is achieved by a special program called a boot.
Gemerally,the boot is stored on the first sector(or two) of a disk.
Hardware is designed to read this sector automatically whenever the power is tuned on.
The boot consists of only a few instructions,but they are sufficient to read the rest of the operating system into memory;note how it is seemingly"pulled in by its own bootstraps."
Now,a user can type the commands to load and execute an application program.
6.5 An example(P120-14)
Let's use a brief example to summarize what we've learned about the operating system.
As we begin,main memory is empty,and a disk containing the boot, the operating system,and an application program has been loaded into the disk drive.
As the power is turned on,the boot flows into main memory,and its instructions are executed;as a result,the operating system is copied from disk.
Now,the operating system's command prcessor module has control of the computer.
It displays a prompt and waits for the user to enter a command.
The user tells the system to load a program.
The command processor reads and interprets the command,and gives control to its program loading module.
Since loading a program calls for accessing disk,this module,in turn,calls the input/output control system.
The IOCS finds the requested program and copies it into main memory,
Control then returns to the command processor,which displays a prompt and waits for the next command.
The next command is RUN.
The command processor reads and interprets it and transfers control to the module that starts applocation programs.
The application program gets control,and the user communicates with it.
Fimally,the application finished,control returns to the command processor,which displays a prompt and waits for the next command.
At this point,the user can load another program,perform a syster function such as formatting a disk,or signoff the syster.
6.6 Some Operating Systems（P121倒9）
MS/DOS is composed of three primary modules.
COMMAND.COM is the command processor.
The functions of the input/output control system are divided between two routines,MSDOS.SYS and IO.SYS.
MSDOS.SYS is hardware-independent.
IO.SYS,on the other hand,communicates directly with the hardware,so it contains device-dependent code.
Versions of the operating system written for different computers should differ only in their IO.SYS logic.
In addition to the primary modules,the operating system contains a number of utiliy programs.
When MS/DOS is booted,COMMAND.COM,MSDOS.SYS,and IO.SYS are copied into main memory.
A transient area in main memory consists of memory not assigned to the operating system.
Appliocation programs,system utilities,certain trasient modules,and data are read into the transient area.
关键字解释（P126）
1.Application program.A program written to perform an end user task.
A payroll program or a computer game are application programs;an operating system is not.
应用程序：为完成最终用户的任务而写的程序，工资程序和游戏程序都是应用。操作系统不是。
2.Boot.A small routine,read into main memory when the computer is turned on,which reads the rest of the operating system into memory.See also initial program load.
引导程序：一小段程序。每次开机就自动地读入内存，然后，由它把操作系统的其余部分读入内存。可参阅初始化程序的装入。
3.Command language.A language for communicating with an operating system.
命令语言：一种用来与操作系统通信的语言。
4.Command processor.An operating system module that reads,interprets,and carries out commands.
命令处理程序：操作系统的一个模块，它读出、解释和执行命令。
5.Operating system.A collection of program modules that control the operation of the computer.A typical operating system allocates resources,schedules programs,controls access to input and output devices,and manages data.
操作系统：程序模块的集合，它控制着计算机运行。一个典型的操作系统能分配资源，调度程序，控制存取 I/O 设备以及管理数据等。
词汇
| across 经过
appropriate 相应 typically 通常 idea 概念、想法 objective 目的 achieve 达到 special 专用 seemingly 从外表看 own 自己的 bootstrap 引导程序 sufficient 足够 brief 简单 summarize 总结 at this poit 至此 |
signoff 停止
compose 组成 primary 主要 in addition to 除…以外 utility 实用 payroll 工资 routine 例行 rest 休息、其余 reset 重置 interpret 解释 carry out 实现、执行 allocate 分配 resource 资源 schedule 调度 |
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6.2.1 命令语言（P130-7）
程序员通过命令语言和命令处理程序进行对话。通常对每个主要功能都有一个简单的字命令—LOAD（把程序从磁盘装入到主存中），FORMAT（格式化磁盘）和 DISKCOPY（复制磁盘）等等。坐在键盘前的用户键入一个命令，这个字符串就从键盘，通过接口板，再经过总线流入主存。这个字符串一进入主存，命令处理程序就解释这个命令，并把控制交给相应的功能模块。
6.4.1 引导程序（P133倒7）
通常操作系统存放在磁盘上，应设法把它复制到主存储器中。用一个称之为引导程序的专用程序可达到这一目的。一般说来。引导程序放在磁盘的第一（或第一、二）扇区。把硬件设计成只要一加电就能自动地读出该扇区。引导程序仅由几条指令组成，但它足以把操作系统的其余部分读入主存。从外表上看，操作系统很象被自己的引导程序拉入主存的。现在，用户能键入命令，装入和执行所有的应用程序了。
6.5 例子（P134-1）
用一个简短的例子总结一下，关于操作系统我们已经学到了些什么。当开始时，主存是空的，含有引导程序、操作系统和应用程序的磁盘已存放在磁盘驱动器中。一加电，引导程序就流入主存了，它的指令被执行，导致了操作系统从磁盘复制到主存。
至此，操作系统的命令处理程序模块控制了计算机。该模块显示提示符，等待用户键入命令。用户告诉系统装入程序，命令处理程序读出和解释命令，并把控制交给其装载模块程序。由于装入程序要访问磁盘，接着该模块调 I/O 控制系统；IOCS 找到所需的程序，并把它复制到主存中。然后，控制退还给命令处理程序，命令处理程序再显示提示符，等待下个命令。
下个命令是 RUN。命令处理程序读入并解释 RUN，把控制权传送给启动应用程序的模块。应用程序得到了控制，用户和它通信。最后，应用程序工作完成了，控制权再退还给命令处理程序，它又显示了提示符，等待下个命令。至此，用户还可以装入另一个程序，完成一个系统功能，如格式化磁盘或停止系统等。
6.6 介绍一些操作系统（P134倒4）
MS/DOS 由三个主要模块组成。COMMAND.COM 是命令处理程序，I/O 控制系统的一些功能划分给两个子程序 MSDOS.SYS 和 IO.SYS 共同完成。MSDOS.SYS 是独立于硬件的，而 IO.SYS 直接与硬件通信，所以它包含取决于设备的编码。为不同的计算机所编写的操作系统版本，仅在它们的 IO.SYS 逻辑中有不同。除了这些主要模块以外，操作系统还包括大量的实用程序。
当 MSDOS 被引导程序装入时，COMMAND.COM、MSDOS.SYS 和 IO.SYS 都被复制到主存。主存中的用户区是由没分配给操作系统的存储单元组成的。一些应用程序、系统实用程序、某些临时性的程序模块和数据都被读进用户区。
7.应用软件
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8.数据管理
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9.系统的分析与设计
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需求：如，建立电子商务网上书店的意义。（P210）
分析：用户注册、购书、系统管理。（P211）
设计：划分功能模块。（P213）
实现：编程实现各功能。（P215）
维护：故障维护、性能改进提高。
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10.多道程序设计
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多道程序：在一台计算机上进行多任务分时操作。（P236）
多重处理：多处理器分享主存。（P240）
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11.计算机网络
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