1. 磁盘操作系统(DOS)：
DOS 代表磁盘操作系统。它是一个单用户(无安全性)，一个单进程系统，将计算机的完全控制权交给用户程序。它比 Unix 消耗更少的内存和功率。
2. UNIX：
UNIX 是一种功能强大的多用户多任务操作系统，最初由 AT&T 贝尔实验室开发。由于其最受赞赏的特性，如灵活性、可移植性、网络功能等，它是科学、工程和学术界非常流行的操作系统。
DOS和Linux的区别：
| S.No. | DOS | UNIX |
|---|---|---|
| 1. | DOS is single tasking operating system. | UNIX are multitasking operating systems. |
| 2. | It is monouser (no concept of more than one user) | UNIX are multiuser (with multiple simultaneous users); |
| 3. | It consumes low power. | It consumes high power. |
| 4. | It has no native support for IP networks. | It come with built-in support for IP networks. |
| 5. | It has 3 proprietary implementations (MS-DOS, IBM DOS and DR-DOS) and one free implementation (FreeDOS). | There are many proprietary and free/open source implementations. |
| 6. | It is not case sensitive. | It is case sensitive. |
| 7. | It is used in embedded systems. | It is mainly used in servers. |
| 8. | It uses backslashes. | It uses forward slashes. |
| 9. | It has no virtual memory nor protected memory. | It usually have virtual memory and protected memory. |
| 10. | It has batch files. | It has shell files. |