Spring 2013 CS 103 Computer Science – Business Problems Instructor: Zhe He Department of Computer Science New Jersey Institute of Technology

Lecture 3 Intro to Information Technology (Part 3) Number System

Feedback A computer assists us, doing whatever we ask it to do We want our “assistant” to report on the progress of the task it is doing We need to know that the task was done and when to give another one Computer systems always give the user feedback about “what’s happenin’ ”

Feedback Feedback is an indication that either the computer is still working or is done Feedback takes many forms: The revision is visible Areas on the screen become highlighted, shaded, gray, underlined, color change, or you might hear a click

Feedback Most common form of feedback is that the computer is performing a time-consuming operation Cursor is replaced by a different icon Some apps give custom feedback Or use a progress bar to give an estimate on time remaining Always expect feedback

Consistent Interface Regardless of who makes the software, icons and menus tend to be similar Especially so within a specific company (Microsoft for example) Look for similar menu names, like File and Edit Look for similar functions within the menus, like Cut, Copy, Paste in the Edit menu

Consistent Interface Why? 1. Companies reuse the same code in each of their applications 2. Aids you in learning and using additional applications 3. Certain operations are so fundamental to processing that all apps just use those oprations

New Instance Under File you usually find a command, New New creates a “blank” instance of the kind of files the application creates What is “blank information”? An empty structure to hold (record) all of the properties of that file and store its content Example: A new/empty address book entry is ready to hold names, images, and phone numbers about the new individual

New Instance for the Address Book

Perfect Reproduction Computers encode information as a sequence of binary digits, 0’s and 1’s Because of the use of two digits, we call it digital information Using only 0’s and 1’s means that digital information can be perfectly reproduced or replicated

Exact Duplicate A second copy is made simply by duplicating the sequence of 0’s and 1’s This is one way digital improves on analog information Analog information comes from or is stored on a continuously variable medium Video camera using tapes versus DVD(hard drive) A copy of an image, for example, could come out too dark or too light when compared to the original

The Perfect Reproduction Property of Digital Information It also doesn’t matter where the copy came from: Both the original and the copy are the same sequence of 1’s and 0’s Every copy can be made from the last copy, and still be identical to the original!

Copying Copy/Paste/Edit Copy and Paste operations are available in many applications When editing a file, you can either create content from “scratch” or use Copy/Paste (C/P) to reproduce it from another location Copy/Paste is generally faster and less error prone

How We Learn Technology Find and ReplaceAll In Find/Replace editing operations, the source content to Find is identified in the document The target content to Replace it with is also identified Find/ReplaceAll (F/RA) is an all-at-once version of Copy/Paste Use an abbreviation of a long name or title as a placeholder, then use F/RA to put in the correct name all at once!

Placeholder Technique When many the purpose or operation of a new technology may seem obvious Some technologies require instruction (driving a car or using a chain saw!) Much of the technology we use we figure out on our own We know intuitively what to do The technology developers did that on purpose!

Metaphors In computing, a metaphor is an icon or image used as representative or symbolic of a computation When designers create a technology, they use metaphors to help users know how to operate their devices without reading a manual Metaphors are a terrific solution!

The Desktop In the ‘70s the first personal computer (the Alto) was developed It was the first computer with a Graphic User Interface when the computer booted Since the computer was designed for business use, the metaphor that was used for the screen was desktop Other business metaphors: files, folder, documents

The Desktop

Steve Jobs and Steve Wozniak founded Apple and built computers without GUIs Jobs saw the Alto and liked the GUI concept Apple redesigned an unsuccessful personal machine (Lisa), then launched the Mac in 1984 Soon after, Microsoft began developing Windows to replace its DOS system

Evolution of the Desktop of MS Windows Windows 3.1 in 1992 Windows 95 in 1995 Windows XP in 2001 Windows 8 in 2012

Evolution of the Desktop of Mac OS Apple Macintosh in 1984 Mac OS 8 in 1997 Mac OS 9 in 1999 Mac OS X Mountain Lion in 2012

More Computer Metaphors The Mac first introduced the mouse to the public…another component in desktop metaphor Apple did not invent it Stanford Research Institute invented the mouse years in December 1968 When introduced, it was stated that they called it a mouse and didn’t know why they didn’t change the name!

Changing Metaphors A new idea, the touch metaphor Users touch the content, smart phones, tablets, and other mobile devices Example: the Cover Flow mechanism for scanning through a list, using a sweeping motion of the pointer

Touch Metaphor Gestures

Metaphor Relationships The touch metaphor is intended to simplify the use of smart phone and tablets This technology is not new (use of stylus and touch screen interaction at kiosks) Touch has no mouse It’s possible to use the touch metaphor with a trackpad or mouse so it is not limited to mobile devices

Why is Touch a Metaphor? It’s a way to eliminate the mouse, but… It changes how humans interact with the computer Scrollbars using the desktop metaphor for moving through a display Small screens don’t have room for scrollbars Direction of motion is opposite between touch and desktop metaphors

Why is Touch a Metaphor? It changes how humans interact with the computer With the touch metaphor, your hands are “on” the content You move the content to where you want it to be With the desktop metaphor you “slide a window over the content”

Summary of Metaphors We use technical metaphors daily They are 100 percent synthetic, created by imagination of the developers They are meant to simplify the use of the devices. The touch metaphor will not replace the desktop metaphor Both have extensively determined how we think and behave with technology

Summary We can figure out software because designers use consistent interfaces, suggestive metaphors, and standard functionality. We should explore a new application by “clicking around” and “blazing away.” Making exact copies is a fundamental property of digital information that we use daily.

Summary Find and ReplaceAll are standard operations that simplify our computer use. Metaphors are essential to computer usage because the guide us in learning and using software. The desktop metaphor is classic; the touch metaphor is newer; they will co-exist.

Number System

Digitizing Discrete Information The dictionary definition of digitize is to represent information with digits. Digit means the ten Arabic numerals 0 through 9. Digitizing uses whole numbers to stand for things.

Limitation of Digits A limitation of the dictionary definition of digitize is that it calls for the use of the ten digits, which produces a whole number Alternative Representations Digitizing in computing can use almost any symbols Any ten distinct symbols will work as long as items are labeled properly.

Symbols, Briefly One practical advantage of digits is that digits have short names (one, two, nine) Imagine speaking your phone number the multiple syllable names: “asterisk, exclamation, closing parenthesis” IT uses these symbols, but have given them shorter names: exclamation point... is bang asterisk... is star

Fundamental Information Representation The fundamental patterns used in computing come into play when the physical world meets the logical world In the physical world, the most fundamental form of information is the presence or absence of a physical phenomenon

Fundamental Information Representation From a digital information point of view, the amount of a phenomenon is not important as long as it is reliably detected Whether there is some information or none; Whether it is present or absent In the logical world, concepts of true and false are important

Fundamental Information Representation Logic is the foundation of reasoning It is also the foundation of computing The physical world can implement the logical world by associating “true” with the presence of a phenomenon and “false” with its absence

A Binary System The PandA encoding has two patterns: present and absent Two patterns make it a binary system There is no law that says on means “present” or off means “absent”

Bits Form Symbols In the PandA representation, the unit is a specific place (in space and time), where the presence or absence of the phenomenon can be set and detected. The PandA unit is known as a bit Bit is a contraction for “binary digit” Bit sequences can be interpreted as binary numbers Groups of bits form symbols

Bits in Computer Memory Memory is arranged inside a computer in a very long sequence of bits Going back to the definition of bits (previous slide), this means that places where the physical phenomenon encoding the information can be set and detected

Combining Bit Patterns The two-bit patterns gives limited resources for digitizing information Only two values can be represented The two patterns must be combined into sequences to create enough symbols to encode the intended information

Hex Explained Hex digits, short for hexadecimal digits, are base-16 numbers A bit sequence might be given in 0’s and 1’s: Writing so many 0’s and 1’s is tedious and error prone There needed to be a better way to write bit sequences…hexadecimal digits

The 16 Hex Digits The digits of the hexadecimal numbering system are 0, 1,..., 9, A, B, C, D, E, F Because there are 16 digits (hexits), they can be represented perfectly by the 16 symbols of 4-bit sequences: The bit sequence 0000 is hex 0 Bit sequence 0001 is hex 1 Bit sequence 1111, is hex F

Hex to Bits and Back Again Because each hex digit corresponds to a 4- bit sequence, easily translate between hex and binary B A D F A B

Digitizing Numbers in Binary The two earliest uses of PandA were to: Encode numbers Encode keyboard characters Representations for sound, images, video, and other types of information are also important

Counting in Binary Binary numbers are limited to two digits, 0 and 1 Digital numbers are ten digits, 0 through 9 The number of digits is the base of the numbering system Counting to ten

Counting in Binary With decimal numbers, we use a place value representation where each “place” represents the next higher power of 10 With binary numbers, it is the same idea, but with higher powers of 2

Place Value in a Decimal Number Recall that To find the quantity expressed by a decimal number: The digit in a place is multiplied by the place value and the results are added Example, 1010 (base 10) is: Digit in the 1’s place is multiplied by its place Digit in the 10’s place is multiplied by its place and so on: (0 × 1) + (1 × 10) + (0 × 100) + (1 × 1000)

Place Value in a Binary Number Binary works the same way The base is not 10 but 2 Instead of the decimal place values: 1, 10, 100, 1000,..., the binary place values are: 1, 2, 4, 8, 16,...,

Place Value in a Binary Number 1010 in binary: (1 × 8) + (0 × 4) + (1 × 2) + (0 × 1)