What is the difference between pages and blocks? A block is the smallest unit of data that an operating system can either write to a file or read from a file. What exactly is a page? Pages are used by some operating systems instead of blocks. A page is basically a virtual block. And, pages … Read more
Short Answer: They are different things. A system call is call by software running on the OS to services provided by the OS. An interrupt is usually external hardware component notifying the CPU/Microprocessor about an event that needs handling in software (usually a driver). I say usually external, because some interrupts can be raised by … Read more
The following statement in your question is wrong: What I know is that a part of the physical memory is reserved to communicate with the hardware A part of the physical memory is not reserved for communication with the hardware. A part of the physical address space, to which the physical memory and memory mapped … Read more
The absolute “bible” on operating system design is and was Andrew Tanenbaum’s Operating Systems Design and Implementation – the “Dragon” book 🙂 There are plenty of other references, too, e.g. Developing Your Own 32-Bit Operating System. Microsoft Research also has/had a project on creating an operating system in managed code (C#) called Singularity – that … Read more
For my final year project in collage I developed a small x86 OS with a virtual memory manager, a virtual file system and fully preemptive multitasking. I made it open source and the code is heavily commented, check out its source forge page at: https://github.com/stephenfewer/NoNameOS From my experience I can recommend the following: You will … Read more
The reason that when using FIFO, increasing the number of pages can increase the fault rate in some access patterns, is because when you have more pages, recently requested pages can remain at the bottom of the FIFO queue longer. Consider the third time that “3” is requested in the wikipedia example here: http://en.wikipedia.org/wiki/Belady%27s_anomaly Page … Read more
DOS inherited CR-LF line endings (what you’re calling \r\n, just making the ascii characters explicit) from CP/M. CP/M inherited it from the various DEC operating systems which influenced CP/M designer Gary Kildall. CR-LF was used so that the teletype machines would return the print head to the left margin (CR = carriage return), and then … Read more
To add something to this: The best explanation I could find for a vnode is here on the FreeBSD docs. For the more academically minded there is also the original paper that introduced the concept, [Vnodes: An Architecture for Multiple File System Types in Sun UNIX], which provides a much more in depth resource. That … Read more
“Process” is well-defined; “job” and “task” are ambiguous. Fundamentally a job/task is what work is done, while a process is how it is done, usually anthropomorphised as who does it. A job is an overall unit of work, and is composed of tasks. In practice usage is very inconsistent, and often “task” == “process”, though … Read more
Well, the answer lives in books: Modern Operating Systems – Andrew S. Tanenbaum is a very good one. The cover illustration below. The simplest yet complete operating system kernel, suitable for learning or just curiosity, is Minix. Here you can browse the source code. (source: cs.vu.nl)