Device Drivers

What is Direct Memory Access (DMA)?

Direct Memory Access (DMA) is a hardware mechanism that lets a peripheral device transfer data directly to or from main memory without routing every byte throu…

Polling vs Interrupt-Driven I/O: What Is the Difference?

Polling is where the CPU repeatedly checks a device’s status register in a loop until it is ready, while interrupt-driven I/O lets the CPU do other work and re…

What is a Device Driver and Why Does an OS Need One?

A device driver is a piece of kernel (or kernel-adjacent) software that translates the operating system’s generic I/O requests into the specific commands a par…

Microkernel vs Monolithic Kernel: Key Differences

A monolithic kernel runs the entire OS — scheduler, file system, device drivers, and networking — in one privileged address space for speed, while a microkerne…

What is a Hybrid Kernel Architecture?

A hybrid kernel is a design that keeps a microkernel-inspired modular structure — separating services conceptually and often loading drivers as dynamically loa…

How Does Interrupt Handling Work in an OS?

Interrupt handling is the sequence by which the CPU detects an interrupt request, saves the currently running task’s state, looks up and runs a dedicated handl…

What is an Interrupt Vector Table?

An interrupt vector table (IVT) is an array of handler addresses indexed by interrupt or exception number, used by the CPU to jump directly to the correct hand…

What are DMA Controller Modes?

Direct Memory Access (DMA) controller modes describe how a DMA engine shares the memory bus with the CPU while moving data between a device and RAM without the…

Memory-Mapped I/O vs Port-Mapped I/O

Memory-mapped I/O places device registers directly inside the same address space as RAM so the CPU accesses them with ordinary load and store instructions, whi…

What is the Virtual File System (VFS) Layer?

The Virtual File System (VFS) layer is an abstraction inside the kernel that defines a common set of file operations — open, read, write, close, and more — so…

How Does an OS Support GPU Computing?

An OS supports GPU computing through a kernel-mode driver that manages GPU memory and command submission, a scheduler that time-slices or preempts the GPU amon…