Computing Intro

Computing Hardware

• CPU
  CU
  alu
• Memory (RAM) - two stable states. About 1G now
  Data - strings, numbers, characters encoded as bits
  Program
  Memory byte is never empty!
  Each byte has an address
  volatile
• Storage Devices
  Disks
  CDs (700 MB), DVDs (4.7GB)
  Tape drives
  USB Flash drives
• I/O Devices
  Keyboard
  Mouse
  Monitor
• Communication Devices
  10BaseT NIC card transfers data at 10 mbps (million bits per sec)

Software

• Systems Software
• Application Software

Operating Systems

• Controlling and monitoring system activities
• Allocation and assigning system resources
• Scheduling operations

Creating Software : Programming

• Machine Language
• Assembly Languages - machine dependent
• High-level Languages
  Cobol
  Fortran
  Basic
  Pascal
  Ada
  C
  Java - syntax is similar to C++. Object-oriented language.
  C# - subset of C++ and similar to Java
  Javascript
  C++ - object oriented language based on C

Scripting -- i.e., Javascript NOT Java

• Code interpretered by Web Browser
  made up of statments - a complete instruction
  lines - readability, usually one statement per line
• No Compiler or IDE needed
• Need to be able to host the page on a server

• Internet
  The amorphous network of networks connecting computers all over the world. This is the physical basis for the World Wide Web, email, FTP, and lots of other applications. Each application has its own protocol, or rules for communicating. The various networks have their own communication protocols, but we can generally ignore them, just as you can make a phone call without knowing how the telephone network works.
• WWW
  The Web runs on top of the Internet. It's a bunch of servers waiting to provide information to browsers upon (authorized) request.
• web page
  Generally, a text data file containing HTML formatted content. We often refer to these as ASCII files – basically characters you can type with a keyboard using a application like Notepad. The files are saved with a file extension of .html instead of .txt, indicating to the OS that this is a web page.
• web server
  A computer on the WWW listening for requests for web pages, images, etc. Simplistically, when a request is received the server finds the file requested and sends it to the browser. This counts as system software.
• browser
  A user application program that lets the user browse the web. This program interprets and displays web pages that are requested by the user. Requests specify the web page using an URL, normally by clicking on a link in the currently displayed page.
• HTTP
  HyperText Transfer Protocol. The rules for how web servers and browsers communicate.
• HTML
  HyperText Markup Language. Hypertext refers to clickable links in the text. (Check out this 1945 description of hypertext by Vanevar Bush. Why is that interesting?) A mark up language refers to a way to control how and where text is displayed on a page.