1. CSCI 3753 Operating Systems Spring 2005 Professor Rick Han Department of Computer Science University of Colorado at Boulder

2. CSCI 3753 Announcements Who am I? Review of syllabus TA introduces first programming shell assignment (similar to lab exercise 2.1) and CSEL logistics Introduction to Operating Systems Read chapters 1 and 2 in the textbook

3. What is an Operating System? Windows, Linux What is an application? –Powerpoint, Realplayer What is hardware? An operating system is a layer of software between applications and hardware Applications Operating System Hardware

4. What is an Operating System? An operating system is a layer of software between many applications and diverse hardware that –helps to better manage the hardware for an application otherwise an application saving a file to disk would have to know how the disk operates –helps to share resources and isolate access to resources between multiple applications App3 Operating System DiskMemoryCPUDisplayMouse App2 App1 I/O

5. What is an Operating System? A PC operating system consists of multiple components –scheduler –virtual memory system –file system –other... App3 DiskMemoryCPUDisplayMouse App2 App1 I/O Scheduler VM File System OS “Kernel”

6. System Libraries and Tools (Compilers, Shells, GUIs) What is an Operating System? App3 Disk MemoryCPU DisplayMouse App2 App1 I/O SchedulerVM File System OS “Kernel” System call API –160 in Linux Device driver “API” Posix, Win32, Java, C library API Note: different OS kernels can support the same system call API OS?

7. What is an Operating System? Distributed Operating Systems –Networked File System –OS adds TCP/IP Network Stack –Device driver support for Networking cards OS HW App1App2App3 Networking HW Networking Stack OS HW App1App2App3 Networking HW Networking Stack Network e.g. Internet, or Ethernet, or WiFi Examples: –App1 is a distributed client server app, e.g. App1 on left is Web browser, App1 on right is Web server

8. Operating System Trends Hardware has evolved quickly - OS must adjust –Moore’s Law applies to CPU speed and/or memory size: doubles every 18 months => exponential! –But Moore’s Law doesn’t apply to disk access speed or to battery life –Diverse devices with high bandwidth requirements Storage Evolution: Punch card stores code 1950s-80s Tape Drive 1950s-80s Disk Drive 1960s-2000s Flash Drive already at 1 GB @ $60 => OS disk scheduling obsolete?? ??

9. Operating System Trends Hardware support for operating systems has evolved too –Mode bit support in CPU user mode vs. kernel/supervisor mode early PCs did not have this support Today’s embedded microcontrollers also lack this support –Page faulting hardware and MMU –Lack of such HW support can allow user programs to accidentally or maliciously overwrite OS kernel code!

10. Operating System Trends Proliferation of OSs on large scale and small scale and across features –Multi-processor OSs - scaling up –Cell phone OSs - scaling down –Real-Time OS for Embedded and Multimedia Systems

11. Operating Systems: Key Concepts Multiprogramming –when CPU idle (e.g. blocked on I/O), run another program => improved CPU utilization 1.batch mode - running jobs or programs sequentially, one after the other 2.Time sharing and concurrency - finely interleaved sharing of CPU useful to give impression of interactivity!

12. Operating Systems: Key Concepts Time-sharing examples –multiple processes sharing time locally on a CPU –multiple user terminals remotely sharing processing time with a central server keystroke delay

13. Operating Systems Research Papers are published at premier OS conferences like: –ACM SOSP 2005 (Symposium on Operating Systems Principles) - http://www.sosp- 20.com/ –USENIX OSDI 2004 (Operating System Design and Implementation) - http://www.usenix.org/events/osdi04/ Secure Operating Systems Wireless Sensor Networks

14. Groups of sensor nodes connected by a wireless networking fabric Sensor nodes consist of CPU/memory, radio, sensors, and power units Monitor environment Interne t Self-configure into wireless multi-hop network

15. Applications of Wireless Sensor Networks Nature Wildlife – Great Duck Island (Berkeley 2002) Home Security (commercial) Medical - Assistive Technology (BP Visualization Center, L3D, Ga Tech) Mobile/Robotic WSANs Habitat – San Jacinto Nature Preserve (UCLA) Monitor atmosphere (NCAR)

16. Military Applications of Sensor Nets Battlefield monitoring Sound, heat, metal, vibration Deployed in Vietnam, Afghanistan, Iraq REMBASS II, UGS, … Basestation Wireless sensor network

17. MANTIS Research Project at University of Colorado at Boulder, Dept Computer Science –Professor Rick Han –10 undergraduate and graduate students –http://mantis.cs.colorado.edu Designed the MANTIS OS for micro sensor nodes - multithreaded, in C Designed the ELF flash file system for micro sensor nodes