Operating systems

Nils Wiki>Formal Sciences>Computer Sciences>Software Systems>Operating systems

Chronological order of happenings at computer startup
Power-up the computer starts all the components All microprocessors act at this stage as an old 8086 processor BIOS which is part of the processor starts up BIOS runs POST BIOS searches for a valid boot-sector A valid boot-sector is found in the first sector of a floppy disc A valid boot-sector end with the identifying bytes 0x55 and 0xAA BIOS loads the first sector from the device into the memory-cell with address 0x7C00 The memory at 0x7C00 is now in control of the machine

Assembler Linker Compiler

Writing an operative system
Write a boot-sector Write a program in C that copies the operative system code to the first sector of a floppy disc (or use Debug) Display a message on the screen