[Knowledge-base] Computer Drivers

What are drivers?

• Whether classified as device drivers or software drivers, they are small software programs.
• Drivers are crucial to the communication between your hardware devices, software and operating system.
• Hardware, such as scanners, requires specialized commands, but software sends more generic instructions.
• When you hit print in Microsoft Word, the command is translated by the driver into a command that the printer understands.
• Some devices might function in what is called "generic mode" without drivers; for example, your display might perform only in low resolution mode.
• This means you are not getting your money's worth out of the investment you made in your hardware.
• If you upgrade your operating systems, purchase a new computer or if your hard drive crashes, you will need to install the correct drivers.

Why you need the latest drivers?

• They will help ensure your system continues to be stable and operate smoothly.
• Drivers are susceptible to corruption; if this occurs, to your modem driver for example, your internet connection will not work properly.
• Companies often update their drivers more than once a year.
• A major reason for an updated driver to be released is to fix a bug.
• This obviously will enhance your equipment's performance.
• As well, updated drivers can bring with them new features.
• By ensuring you have the most up-to-date drivers, you can be sure to get the most out of your PC.

User-mode and Kernel-mode Drivers:

• A processor in a computer running Windows has two different modes: user mode and kernel mode.
• The processor switches between the two modes depending on what type of code is running on the processor.
• Applications run in user mode, and core operating system components run in kernel mode.
• Many drivers run in kernel mode, but some drivers run in user mode.
• Device drivers, particularly on modern Microsoft Windows platforms, can run in kernel-mode (Ring 0 on x86 CPUs) or in user-mode (Ring 3 on x86 CPUs).
• The primary benefit of running a driver in user mode is improved stability, since a poorly written user mode device driver cannot crash the system by overwriting kernel memory.
• On the other hand, user/kernel-mode transitions usually impose a considerable performance overhead, thereby prohibiting user-mode drivers for low latency and high throughput requirements.
• Kernel space can be accessed by user module only through the use of system calls.
• End user programs like the UNIX shell or other GUI-based applications are part of the user space.
• These applications interact with hardware through kernel supported functions.