CS 110 Notes – Computing 1 Copyright C. Tanner 2010 Computing • Hardware o Everything goes through main memory  Including things stored on disk o Types of computers  Super, Mainframe, Mini, Personal • Software o Programs and Data which make computer work o Types  System • Operating System o Purpose is to control hardware and users interaction with computer o Examples -- Windows, Linux • Network Software o Allows sharing of resources and communication between users • Tools o Compilers  High level languages are converted to machine language 1-n Input Main Memory IRPC…etcALUCPU OUTPUT IOCS 110 Notes – Computing 2 Copyright C. Tanner 2010 o Assemblers  Assembly Language programs are converted to machine language 1-1  Application Software • Allows the computer to do something specific • Uses the OS to manipulate the hardware • COTS o Commercial off the shelf o Come as is o General purpose – Word Processor, spread sheet, database, graphics, etc o Special purpose -- Communications, WWW • Special purpose –library, bookkeeping, Video Store, o Embedded -- Cash register, Microwave • Custom Built o Uses a High Level Language such as  JAVA, C, C++, ADA, Basic, Prologue, SPSS, SAS, LISP etc  Each has a specific grammar (rules) which must be translated by a compiler into machine language • Developing Software o Steps/Stages  Understand the Problem • Determine WHAT the program must do • Determine test cases to demonstrate it does what it is supposed to do  Design Solution to Problem  Implement the solution in HLL • Translate the design into HLL  Verify • Test and Debug • With test cases previously determined  Maintain o Problem Solving Techniques  Algorithm • General solution to a problem • analogies – recipe, instructions, graphics to assemble something • formal definition o a step by step procedure for solving a problem in a finite amount of time  Solving by Analogy • Use as a starting pointCS 110 Notes – Computing 3 Copyright C. Tanner 2010  Means Ends Analysis • Determine the beginning and ending objectives then determine how to go from one to the other  Divide and Conquer • Continually and iteratively break the problem into smaller problems (which are more manageable)  Building Block/Composition • Use existing solutions for smaller problems • REUSE model  Merging Solutions • Combine existing solution so as to avoid duplication • Types of Programming Language Statements o Sequential  Performed (executed) in the order they appear o Selection  Chooses between sets of statements based on the value of a Boolean expression o Iteration/Repetition  Repeats a set of statements a number of times or until a condition is reached o Modular  Creates a unit out of a set of statements which can be performed (executed) through a single name • Problem -- Mechanical Man o Statement Set/Instruction Set  Sequential • STAND • SIT • STOP • RAISE • LOWER • STEP • TURN • ADD • SUB  Selection Conditions • ZERO • WALL  Repetition • Repeat Until stmtsCS 110 Notes – Computing 4 Copyright C. Tanner 2010 End Repeat o Test Cases ----CS 110 Notes – Computing 5 Copyright C. Tanner 2010 • Pseudo-Code for Sequential Statements of a General Purpose Programming Language o get  assign value from the user to a variable  example get radius assign value given by user to the variable radius o put  display value of variable to user  example put “radius: “ + radius display the verbiage “radius:” followed by the value of the variable radius o =  Assign variable a value  Examples x =5 assigns the value 5 to variable x x = y+z*c calculates the value of y+z*c and assigns it to x • Problems o Calculate the Circumference and Area of Circle o Test Cases --CS 110 Notes – Computing 6 Copyright C. Tanner 2010 o Convert a Centigrade temperature to its Fahrenheit equivalent. o Test Cases---CS 110 Notes – Computing 7 Copyright C. Tanner 2010 o Pythagorean Triples  A2 + B2 = C2  For m > n a = m2 - n2 b = 2mn c = m2 + n2 o Test Cases—CS 110 Notes – Computing 8 Copyright C. Tanner 2010 • Steps in Developing and Executing a Program o Use text editor to enter the program source code  Call it ProgramName.java o Compile the program  javac ProgramName.java o repeat above until the program is error-free  once error free bytecode version of program will be created • java’s machine language o combine bytecode with System utilities programs  loader  now ready to execute o load program into main memory  interpreter  translates bytecode into machine language