CS 105 Study Guide

Hardware * The parts of the computer that can be kicked * Keyboard, monitor, etc.

Storage * Secondary * Hard drives * CD-ROMS * DVDs * Flash memory * Maintain its data without external power * All programs reside here * Space reclaimed only if program is deleted * Slow, cheap, huge * Primary * Random Access Memory * Active programs run here * Space reclaimed when active program finishes * Volatile- data lost when power turned off * Fast, expensive, limited

Software * Instructions that tell the hardware what to do * Sequence of instructions * Usually does not have direct access to hardware * Access mediated by the Operating System (OS)

Operating System * Software * Manages hardware. Tell it: * What to do * When to do it * How to do it * How to allocate its resources * Manages the data, the memory, and the appearance * VISTA, Mac OS X, iPods, Handhelds- Palm OS, UNIX are examples * The company that makes an OS has an advantage in making applications for that OS * Internet Explorer loads much faster than Firefox on a PC * Open Source Software: Instructions made available in human readable form * More likely to find and fix errors * Market for competitors because it is safer * LINUX is example * Windows is closed-source * Fewer problems with viruses * Graphical User Interface (GUI) * A type of interface that allows user to interact with icons

RAM * AKA Primary memory * Stores program instructions and data needed for processing—the working memory (short-term memory) of a computer * The primary storage area for programs and data in active use * Volatile * Analogy * Like the size of your desk. Only can fit as many projects as they fit on the desk

Motherboard/Processor * Brain of the computer

Machine cycle 1. Main memory fetches 2. Control unit decodes 3. Arithmetic/logic unit executes 4. RAM stores * Continuous process * Very fast
Main Memory (Ram) * Organized as a sequence of locations * Each location can contain a sequence of bits representing data or an instruction * Locations are numbered with addresses from 0 to memory-size * Fixed amount at each address * Random access * Can directly jump to any location in one step * Can do a “relative jump” in one step * Unlike a tape memory: rewind or fast forward
Binary Numbers * ON or OFF switch * Easy