Computer-system operation

Computer-system operation

One or more CPUs, device controllers connect through common bus providing access to shared memory. Each device controller is in-charge of a specific type of device. To ensure orderly access to the shared memory, a memory controller is provided whose function is to synchronize access to the memory. The CPU and other devices execute concurrently competing for memory cycles. Concurrent execution of CPUs and

devices competing for memory cycles When system is switched on, ‘Bootstrap’ program is executed. It is the initial program to run in the system.



This program is stored in read-only memory (ROM) or in electrically erasable programmable read-only memory(EEPROM). It initializes the CPU registers, memory, device controllers and other initial setups. The program also locates and loads, the OS kernel to the memory. Then the OS starts with the first process to be executed (ie. ‘init’ process) and then wait for the interrupt from the user. Switch on–> ‘Bootstrap’ program

▪ Initializes the registers, memory and I/O devices
▪ Locates & loads kernel into memory
▪ Starts with ‘init’ process
▪ Waits for interrupt from user