CSC103 How Computers Work

Notes1

Course Introduction

1. Class List
2. Goals
3. Syllabus Review
4. Prerequisites
5. Mechanics
   • Assignments, Quizzes, Take-Home/Paper
   • No Textbook
   • TAs & TA Lab hours

Operating Systems

1. Operating Systems
   • What:
     • software to manage the hardware,
     • to interface between applications software and hardware

     • Mode	What	Hard/Soft
       User	Applications: Browser, E-mail client, iTunes, etc.	Software
       	User Interface
       Kernel	Operating System
       	Hardware	Hardware

     
     
   • History:
     • Originally binary switches (see image to right)
     • Early operating systems concentrated on disk interface
       • Unix (1970)
         • Unix video: Ken Thompson & Dennis Ritchie
       • DOS (1980): IBM PC
       • MacOS (1984): Macintosh; completely graphical
       • Windows (1987), NT, ME, XP, Vista, V7
       • Linux (1991)
       • MacOS X (2001)
   • Components
2. Memory Management
   • Size: bits(b) and Bytes(B) [quick intro: more in Notes3]
   • Hierarchy:
     • registers,
     • cache,
     • RAM (Random Access Memory),
     • magnetic disk,
     • optical disk,
     • tape
   • Management
     • Virtual memory
3. Process Management
   • Time Sharing / Multitasking
   • CPU management: executes instructions in RAM
   • Swapping
   • Security: kernel mode vs. user mode
   • Protection against crashes with "virtual machines"
   • Monitoring Processes
     • Unix $ top
     • Mac: Utilities / Activity Monitor
     • Windows: Control-Alt-Del, Task List
       • Windows Task Manager
         • Processes
         • Performance
4. Device Interfacing
   • Devices
   • Device drivers: what doesn't fit on BIOS
   • Interrupts (avoids polling loops)
     • Keyboard: Interrupt lines, CPU address stack, runs instructions specific to that interrupt, resumes
     • Disk: each read/write causes an interrupt when finished.
5. File System Management
   • Directory trees (= folder nesting)
   • disk scheduling
   • fragmentation
     • ~happens automatically in MacOS / Unix=Linux
6. Booting-Up (boot-strapping)
• BIOS: Basic Input/Output System
• checks RAM, devices attached (keyboard, etc.)
• Then OS loads from disk to RAM, loads device drivers, etc.
7. Future of Operating Systems?
   • Google Chrome: "lightweight OS for netbooks"; to boot in a few seconds
   • Minority Report OS
     • Gestural OS: g-speak video