CSE 131 Chapter Notes - Chapter 1: Direct Memory Access, Random-Access Memory, Call Stack
Document Summary
Fetches instructions from memory and executes it. Fetch, decode, execute until the program finishes. Program counter: contains memory address of next instruction. Stack pointer: points to the top of current stack in memory. Program status word: contains condition code bits, used in system calls and i/o. Ram: random access memory aka main memory. Non-volatile ram: does not lose its contents when the power is switched off. Made up of a controller and a device and accepts commands from the os. Input and output can be done in 3 ways. Busy waiting: a user program issues a system call, which the kernel then translates into a procedure call to the appropriate driver. Then the driver starts the i/o and sits in a tight loop continuously polling the device to see if it is done. When the i/o is completed, the driver puts the data where they are needed and returns.
