Institute for Personal Robots in Education (IPRE)‏ CSC 170 Computing: Science and Creativity

Processors do the work Memory stores instructions and data while computer is running Peripherals such as keyboard, disks, trackpad or mouse, … WHAT’S IN THAT COMPUTER? 2

Can perform a small set of basic operations ("instructions") arithmetic: add, subtract, multiply, divide fetch information from memory, store results back into memory decision making: compare numbers, letters decide what to do next depending on result of previous computations control the rest of the machine Operates by performing sequences of simple operations very fast Instructions are stored in the same memory as the data CPU is a general-purpose device: putting different instructions into the memory makes it do a different task this is what happens when you run different programs THE CENTRAL PROCESSING UNIT(S) 3

A place to store information such as the programs that are running the data (numbers, strings, pictures, music) the operating system (Windows, Mac OS X, Unix/Linux,...) Volatile: forgets everything when power is turned off Limited (though large) capacity Logically, a set of numbered “boxes” to store 8 ‘ones’ & ‘zeros’ Random access: CPU can access “box” 4 as quickly as 998 RANDOM ACCESS MEMORY (RAM) …998999

A place to store information, often based on magnetic surfaces, rotating machinery, and increasingly solid-state Flash memory logical / functional structure: folders (directories) and files your information: papers, mail, music, web page programs and their data: Firefox, Word, iTunes operating system(s): Windows, MacOS, Unix, Linux LOCAL DISK DRIVE STORAGE 5

A place to store information that you can access from anywhere Where we will store our Computational artifacts THE CLOUD 6

Numbers, strings, photos, music are stored in binary format usually written as zeros and ones: Can be implemented as two voltage levels (chips), electrical charge present/not present (Flash), magnetized this way or that (disks), light bounces off/doesn't bounce off (cd-rom, dvd) One byte has 8 bits BINARY DIGITS (BITS) 7 One bytedata ‘A’ (65) ‘B’ (66) ‘a’ (97) true false

NUMBER SYSTEMS Decimal numbers multiply digits by powers of = 9x x x x10 0 Octal numbers: powers of = 1x x x x 8 0 = = Hexadecimal numbers: powers of 16 (A is 10) 1CF 8 = 1x x x16 0 = = Binary numbers: powers of = 1x x x x2 0 = = 13 10

CONVERTING BASE 10 TO BASE 2 1) divide number (5) by new base(2), write remainder (1) 2) divide quotient (2), write new remainder (0) to left 3) divide quotient (1), write new remainder (1) to left _ _ 2_ 2 ) 5 Remainder = 1 __1_ 2 ) 2 Remainder = 0 __0_ 2 ) 1 Remainder = 1 Stop when the quotient is 0: 5 10 = 101 2

Depends on how it is used Could be an instruction, number, text, sound, or image The sequence of bits that represents an instruction may also represent data processed by that instruction a character/letter may also represent a number a color in an image a sound in an audio file Bits can represent anything INTERPRETATION OF A BINARY SEQUENCE

A color is represented by 24 bits That is 2 24 or 16,777,216 possible colors 8 bits each for RED, GREEN, and BLUE Color red = new Color(255, 0, 0); Or in binary: Color green= new Color(0, 255, 0); Color black = new Color(0, 0, 0); Color white= new Color(255, 255, 255); REPRESENTING COLOR

Physical layers of computing hardware, including gates, chips, and components A component can be low level like a transistor or high level like a video card A logic gate can model a Boolean function, which is either true or false A chip is an composed of low-level components and circuits that performs a specific function such as memory, CPU, encryption, and more BINARY DATA IS PROCESSED BY…

Computing facilitates exploration and the creation of computational artifacts Tools and techniques to do this include programming languages, spreadsheets, text editors, 3D printers We be using an environment written in HTML5 running in a browser BIG IDEA 1: COMPUTING IS A CREATIVE ACTIVITY 13

Computing allows us to translate intention into computational artifacts Computational artifacts are created by humans using computers Examples of computational artifacts: digital music, videos, drawings, documents, programs, presentations, designs, web pages, … COMPUTATIONAL ARTIFACTS 14 An ExploreLearning Gizmo

A computational artifact may have weaknesses, mistakes, or errors depending on the type of artifact We can analyze computational artifacts for correctness, functionality, and suitability An architectural design created by AUTOCAD program may not have any errors, but it may be ugly to some Programs can also analyze what we do The functionality of a computational artifact may be related to how it is used or perceived The Internet can be bad or good ANALYZING COMPUTATIONAL ARTIFACTS 15

Computer music can be created by synthesizing sounds or manipulating recorded sounds Computing allows us to create digital effects, images, animations, which has transformed movies CGI: Computer Generated Images Also have tactile output Can explore synthetic (fractals) and real phenomena simulate a nuclear reactor simulate recombinant enzymes on DNA COMPUTING EXTENDS TRADITIONAL FORMS 16

Can be written or creative expression or to satisfy personal curiosity May have visual, audible, or tactile results, but may affect a computer or system without such results May be developed with different standards or methods than programs developed for widespread distribution A program or the results of running a program may be shared with others PROGRAMS

Block structured languages use drag and drop development High-level programming languages are easier for humans to read and write code Low-level programming languages, assembly, are close to the machine level Compilers or interpreters translate into the binary code the processor uses PROGRAMMING LANGUAGES add $v0 $t1 3 solve(x,y)

Programs can be developed to solve problems create new knowledge help people, animals, organizations, society, the planet Computer Programs will be our main computational artifact On a much smaller level than Facebook, or I Tunes, or the companies on the next slide PROGRAMS 19

Creativity, Computing, & Collaboration are prominent forces in innovation Innovations have had and will continue to have far- reaching impact Need strong business skills too 3 CEES 20 PayPal Mafia

We will be using the block-structured language SNAP! Developed by U.C. Berkeley Based on MIT’s Scratch Added functionality to allow university level features What does this block of code do? LET US CREATE A PROGRAM 21

Advanced Placement Computer Science Curriculum Framework Dan Garcia at U.C. Berkeley Brian Kernighan at Princeton ExploreLearning ‘s Gizmo product Fareed Zakaria REFERENCES 22