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Showing posts from June, 2015

SCRUMble ! - New Book about SCRUM

 SCRUMble ! Hello Blog Readers! Thank you for all your support and encouragement. I have something exciting for you all. I have recently written and published a new book called 'SCRUMble !'. It is currently available on pothi store. It will be soon available on Amazon and Flipkart as well. Please get your copy and do let me know your reviews. -Abhishek Sathe SCRUMble ! Written and Published by: Abhishek Sathe                                                                              Distributed by: pothi.com Order your copy now:  https://store.pothi.com/book/abhishek-sathe-scrumble/ Coming soon on Amazon and Flipkart About the book: Scrum is a framework for solving complex problems largely adapted by Software Development field. There are multiple ag...

Interrupts

Interrupt is any event that causes CPU to make a temporary transfer of control from its current program to another program that services the interrupt (event). Interrupt Service Routine (ISR) relates specifically to the event that caused the interrupt. Classification of Interrupts: 1. Software Interrupts (Exceptions) and Hardware Interrupts 2. Maskable Interrupts (usually software interrupts) and Nonmaskable Interrupt Vector Table (IVT) is a table of interrupt vectors that associates an interrupt handler with an interrupt request in a machine specific way.

Operating Modes

1. Real Mode - 20 MB of segmented memory adress space, direct software access to BIOS routines and peripheral hardware, no concept of memory protection or multitasking. 80286 and further start with real mode. 2. Protected Mode - expanding addressable physical memory to 16 MB and addressable virtual memory to 1 GB. Provided protected memory. This is done by using segment registers only for storing an index to segment table. Global Descriptor Table (GDT) & Local Descriptor Table (LDT) each giving access to 64 KB of memory. The segment table provided a 24-bit base address, which can be added to desired offset to create an absolute address. 80386 introduced support in protected mode for paging which made it possible to use paged virtual memory.