CISC 110 Day 1 Hardware, Algorithms, and Programming

Outline Structure of Digital Computers Programming Concepts Output Statements Variables and Assignment Statements Data Types String and Numeric Operations 2

Structure of Digital Computers I/O Devices Input/Output Devices: (e.g. Keyboard, Mouse, Webcam) Communication between the computer and the user, and with other computers Secondary Storage Long-term memory of data and programs (e.g. hard drive) 3 CPU (Central Processing Unit): Calculations and the Fetch-Execute Cycle Main Memory RAM (Random Access Memory): Short-term memory of data and programs, while computer is powered on

Main Memory (RAM) byte 3025 byte 3026 byte 3027 byte 3028 byte 3029 byte 3030 byte 3031 byte 3032 byte 3033 byte 3021 byte 3022 byte 3023 byte byte memory location at address 3021: could hold a 16-bit integer 4 byte memory location at address 3024: could hold a 32-bit integer 1 byte memory location at address 3030: could hold one letter 4

Memory Sizes MemoryConversion 1 bit 1 nybble4 bits Either 1 or 0 1 kilobyte 1 byte 2 10 bytes (approx bytes) 8 bits 1 terabyte 1 gigabyte 1 megabyte2 20 bytes (approx kilobytes) 2 30 bytes (approx megabytes) 2 40 bytes (approx gigabytes) 5

Computers: A Definition Computers are machines that can carry out routine mental tasks by performing simple operations at high speeds (operations built into the hardware: machine operations). 6

A Definition of an Algorithm An algorithm is a sequence of instructions that describes how to carry out a task. 7

A Mathematically Precise Definition of an Algorithm An algorithm is a finite sequence of unambiguous, executable instructions for carrying out a task or process in a finite amount of time. Note: This assumes no intelligence on the part of the user. The intelligence and knowledge of a person is encoded in the algorithm. 8

A Definition of a Programming Language A programming language consists of a repertoire of possible instructions, each of which can be specified in terms of the simple operations (machine operations) a computer can execute. 9

Cake-making & Computation Electronic Computer Oven & Utensils (Hardware) Bit String: Numbers or Characters Cake Ingredients (Input) Bit String: Numbers or Characters Cake (Output) 10 Program/Software Recipe (Algorithm)

A Definition of a Scripting Language A scripting language is a programming language that allows control of an application, for instance an animation. The name script is derived from the written script of the performing arts, which tells the actors what to say. 11

ActionScript Trace() Purpose: To display values in the output panel to trace the state of an animation Examples: trace( 525 ); trace ( “Now starting love scene” ); trace ( “Row ” “Col ” + 7 ); trace ( ); trace ( “5 + 7 = ” ); 12

Defining Variables to Store Values Memory: row var row = 5; row = 8; var next = row + 1; next = next + 1; var s = “hi”; var val = 3.5; ActionScript: val s next 13

Data Typing Variables ActionScript: var row: int = 5; row = 8; var next: int = row + 1; next = next + 1; var s: String = “hi”; var val: Number = 3.5; 14

String Operations Operators: +Concatenation +=Append Escape Sequences: \nNew Line \t Tab \’Single Quote \”Double Quote \\Backslash Examples: trace( “Hey” + “you” ); trace( “Hey\nyou” ); trace( “Hey\tyou” ); trace( “Hey\”you\”” ); 15

Arithmetic Operations Operators: +Addition -Subtraction *Multiplication /Integer Division % Mod (integer remainder of division) 16

Imperative Programming Statements: Variable Assignment (=) Branching (if, else) Loops (while, for) Data Structures: Integers Strings Arrays Classes Functions 17