When building your own operating system, the moment when you first write data to a real physical hard disk of a real PC is nothing less than thrilling - after all, making a mistake at this point could mean that you happily overwrite data on your hard drive randomly and wipe out important data on … Continue reading Accessing your hard drive – the OS developers moment of truth
The first PC on which I was running a copy of Linux back in the nineties did of course only have one CPU, so it was clear to me that it could physically only execute one instruction at a time - but still, it magically created the impression to run several programs in parallel without … Continue reading How does multitasking really work?
Modern operating systems are mostly event driven - network cards receive packets, users hit keys or a mouse buttons, built-in timer create events or data arrives from a hard drive. To be able to process these events, a CPU needs a mechanism to stop whatever it is currently doing and run some code designed to … Continue reading Interrupts – the heartbeat of a Unix kernel
