Part 1: Keyboard → CPU 1. When you press a key (say Enter), the circuit under those key closes and generates an electrical signal. The keyboard’s microcontroller converts this into a scan code (a number that represents which key was pressed).

2. Sending data to CPU: The scan code is sent (via USB or Bluetooth) as a stream of bits (0s and 1s) to your computer. This enters the system through the I/O controller (Input/Output controller), which is connected to the CPU.

Part 2: CPU & Interrupts. Interrupt signal the keyboard triggers an interrupt (like saying “Hey CPU, stop what you’re doing and handle this key press!”). The CPU temporarily pauses its current task and calls the keyboard interrupt handler (small piece of code in the OS).

CPU processes scan code The CPU loads this scan code into a register (its small fast storage). Then it gives the data to the keyboard driver (software in the OS).

Part 3: RAM’s Role: RAM stores program + data o The OS and drivers are already loaded in RAM (from disk/SSD). When the CPU runs the keyboard driver, it fetches instructions from RAM.

The scan code itself may also be stored in RAM temporarily while being processed.

Translation The OS translates the scan code → into a character or an action (e.g., Enter = new line or button click).

Part 4: Back to Operating System 7. Event sent to active program o The OS sends a “key event” to whichever app is active (like Chrome, Word, etc.). o That app decides what to do (e.g., Chrome passes it to YouTube’s Subscribe button).

Simplified Hardware Flow:

• Keyboard → electrical signal → scan code

• I/O controller → sends it to CPU • CPU → receives interrupt, pauses, executes keyboard driver

• RAM → stores driver code and data

• OS → translates scan code into a character/action • Application → receives the event