1. 13.1 Silberschatz, Galvin and Gagne ©2007 Operating System Concepts with Java – 7 th Edition, Nov 15, 2006 Quiz  a. Why is LOOK better than SCAN?  Answer the following two questions using exactly one of the words FCFS, SSTF, SCAN, LOOK, C-SCAN, C-LOOK  b. Which algorithm possibly results in starvation?  c. Which of SCAN or C-SCAN gives better throughput?

2. 13.2 Silberschatz, Galvin and Gagne ©2007 Operating System Concepts with Java – 7 th Edition, Nov 15, 2006 Where is RAID, or is SSTF implemented?  OS* … disk  cheap … expensive  older … newer  serial … parallel (offload work and complexity)  logical … physical  volume: logical disk; may span physical disks, or may have several volumes on a physical disk  OS must keep track of physical disks to do * above.  Third alternative in middle is possible:  OS … controller card (host bus-adapter) … disk

3. Operating System Concepts with Java – 7 th Edition, Nov 15, 2006 Silberschatz, Galvin and Gagne ©2007 Excerpt from Chapter 13

4. 13.4 Silberschatz, Galvin and Gagne ©2007 Operating System Concepts with Java – 7 th Edition, Nov 15, 2006 How Does Plug and Play (PnP) work?  Reassigns port and maskable interrupt to avoid collision with another device.  Port: device register mapped to small amount of memory to provide control information.  (Contrast: Memory-mapped device, where large amount of memory provides data to or from the hardware.)  MIRQ and NMIRQ wires provide interrupt number, telling what interrupt occurred, provided by the CPU.  (Contrast: Interrupt level, which is a priority set by OS.)

5. 13.5 Silberschatz, Galvin and Gagne ©2007 Operating System Concepts with Java – 7 th Edition, Nov 15, 2006 Device I/O Port Locations on PCs (partial)

6. 13.6 Silberschatz, Galvin and Gagne ©2007 Operating System Concepts with Java – 7 th Edition, Nov 15, 2006 Pentium maskable vs. non-maskable interrupts

7. 13.7 Silberschatz, Galvin and Gagne ©2007 Operating System Concepts with Java – 7 th Edition, Nov 15, 2006 Windows XP Interrupt Request Levels

8. 13.8 Silberschatz, Galvin and Gagne ©2007 Operating System Concepts with Java – 7 th Edition, Nov 15, 2006 A Typical PC Bus Structure

9. 13.9 Silberschatz, Galvin and Gagne ©2007 Operating System Concepts with Java – 7 th Edition, Nov 15, 2006 Characteristics of I/O Devices