Hierarchy

Hierarchy in computing

File system hierarchy

The most common type of hierarchy in computing is a file system, in which computer files are placed somewhere in a hierarchical tree structure. File systems have a top level that is referred to as the root of the file system. Under the root are subdirectories such as Program Files, Documents, and Setting. Under these subdirectories are more subdirectories.

Memory hierarchy

Similarly, computer memory ranks components in terms of response times. Since response time, complexity, and capacity are related, the levels may also be distinguished by their performance and controlling technologies. There are four major memory storage levels:

1. Internal: Such as processor registers and cache
2. Main: Such as the system RAM and controller cards
3. Online mass storage: Such as secondary storage
4. Offline bulk storage: Such as tertiary and offline storage

While this is a general memory hierarchy, there are other useful structures out there.

Computer System Level Hierarchy

Computer System Level Hierarchy (CSLH) is the combination of different levels that connect the computer with the user and that make use of the computer. In addition, it describes how the computational activities are performed on the computer and the elements used in different levels of the system. CSLH consists of seven levels:

• Level 0: Related to digital logic
• Level 1: Related to control
• Level 2: Consists of machines
• Level 3: Consists of system software
• Level 4: Consists of assembly language
• Level 5: Consists of high-level language
• Level 6: Consists of users and executable programs.