Outline for April 4, 2007

1. Greetings and felicitations!
   1. My office hours
   2. How to submit homework over MyUCDavis
2. What is an operating system?
   1. Began with common I/O routines
   2. Went on to scheduling jobs
   3. Modern: now manages resources on computer: time, disk space, reading and writing, and so forth
3. Example 1: reading what you type
   1. Interrupts and all that (IRQ, controller, vectors)
   2. How the computer remembers where it was when the interrupt arrives
   3. How the computer processes the interrupt
   4. How the computer picks up where it left off
   5. Nested interrupts
4. Example 2: writing a file to disk
   1. Device drivers and direct memory access
   2. Operating system checks request to write (file name legal, file does not exist or is writable, and so forth)
   3. Operating system tells device driver where to put the file
   4. Device driver interacts with disk hardware to copy file out; done in chunks (blocks)
5. Example 3: turning on a Plug-and-Play Windows based system
   1. BIOS identifies devices by unique numbers burned into devices' read-only memory (ROM)
   2. Windows creates enumerators, one per type of device (ISA for hard drives and cards, port for keyboard and mouse, and so forth)
   3. Windows allocates interrupts for each device based on enumerators
   4. Windows then loads appropriate device drivers to use those interrupts