标题DOS Command

　　COMMAND.COM is called a command processor because it reads any commands that you type and processes them. Some commands are recognized and carried out by COMMAND.COM itself. These commands are called internal command. Other commands are separate program located on hard disk or floppy disk， which Dos runs them just like your other program. These commands are called external commands.
　　After you type a command at the command prompt and DOS prompts the message "Bad command or file name". Bad command imples internal command error and Bad file name imples external command error.
　　DOS 为用户提供了许多命令，使用这些命令，用户可以达到有效使用计算机的目的。DOS命令分为内部命令和外部命令两类。
　　COMMAND.COM因为能读出你键入的任何命令并处理它们和处理你输入的命令，所以被称为命令处理程序。有些命令能被COMMAND.COM自己辨认和执行，这些命令称为内部命令。其它命令是分开放在硬盘或软盘上的程序，DOS执行他们就象执行你的其它程序一样，这些命令称为外部命令。
　　在命令提示符下键入一条命令后，DOS提示“Bad command or file name”的信息，Bad command意指内部命令错，而Bad file name意指外部命令错。