Computing System: dynamic entity used to solve problems and interact with its environment.
Computer hardware: collection of physical elements that make up the machine.
Computer software: collection of programs that provide instructions
Layers of a Computing System: Information->Hardware->Programming->Operating systems-
Information: How we represent information on a computer using binary digits.(Ch2,3)
Hardware: Physical hardware of a computer system that keeps the flow of electricity (4,5)
Programming: Uses software instructions used to complete computations. (6-9)
Operating System: Manages computers resources (10,11)
Applications: Help take advantage of the computer’s abilities in other areas. (12-14)
Communications: Use technology to communicate through computers (15, 16)
Abstraction: Mental model that removes complex details.
File: a name collection of related data made from 0 and 1.
File System: operating systems logical views of files it manages
Directory: A named group of files (folder)
Text-file: a file where the bytes of data are organized as characters from Unicode
Binary: a file that contains data in specific format, requiring interpretation
File-Type: Indicated the file type
Atomic Operations: delete, open, close, rename, copy
Processing Data: read, write, remove and add data
Sequential Access: information is processed in order
Direct Access: Files are accessed in a logical order
File Protection: primary importance to keep our files safe. Determines who uses the files
Directory Tree: file systems are organized into a hierarchy
Root Directory: where the file system starts
Path: location of files in a file system though a series of directory
Absolute Path: begins at the root directory
Relative Path: begins at the current or working directory
Working Directory: the subdirectory in which you are working.
LEFT The leftmost characters from the specified text
IF If the test is true, it returns true_val, otherwise it returns the false_val
ISBLANK Returns true if the specified value refers to an empty cell A1…B9 Range of cells
Sum Sum or specified of set
Count Count the # of cells
Max Largest value from the
SIN The sine of specified
PI Value of pi
STDEV Standard deviation from
the specified sample
TODAY Todays date
Information system: software that helps us organize and analyze data
Spreadsheet: A software application that allows the user to organize/analyze data using a grid of
Cell: Referred to by column and row. It can numerical data or string (text).
Range: A1..B9, two dots between two cells.
CH 3: Data And Computers
Analog and Digital Information:
Real world is infinite and continuous
Data on computers are finite
Need to obtain a finite approximate of the world, sufficient for our computational needs
and 5 senses.
Analog data: info represented in a continuous form
Digital data: info represented in a discrete form; sound of record vs disk.
Information is digitized by breaking into numbered pieces
Binary (0 or 1)
2 bits produce 2^n different bit pattern
actual number of bits is influences by other factors
English: 26 letters
Determine the minimum number of bits needed and pair them off. ADCII
Each character is coded as 8 bits, (0-7)
2^7 (128 codes)
95 graphical (visible), 33 control (invisible)
Unicode Character Set:
16-bit standard (2^16)
Substitute a frequency used word with a single character. Ex: as(^), and(+), that($)
Problems: character can’t be apart of the text. Word variations not handled.
Run Length Encoding
Replace long series of repeated characters with a count of repetition. Ex: AAAAAAAA = A7
Generalization of Morse code
Dots and dashes is based on distribution of letters
Distribution in a given message the algorithm.
Encoding: build frequency table of letter usage in message, build the code, encode the
Decoding: Huffman code has the prefix property( no code is the front part of another code)
Physical of sound
Carried by an electronic wave
Electronic wave is an analog (continuous functions)
Audio formats: mp3( MPEG Audio layer 3, uses lossy( math models of human
sychoacoushes to discard info the human ear can’t hear) and lossless(bit stream
compressed by a form of Huffman encoding) compression, wav, aiff
Images and Graphics
Raster: image divided into rows and columns
Pixel: each rectangle hold picture info
Compression takes up a lot of space
Vector graphics math equations to represent shapes
Good for line art/cartoons
Representing Real Numbers:
Base: b any integer is greater than 1. Representing Video
A stream of images at 24-30 frames/second
Temporal compression: key frame + series of delta frames that record only changes from
Spatial compression: removes redundant info within a frame (jpeg like compression on
Birth of The Computer:
- Designed the ‘Z’ series of automatic general purpose computing machine
- -Electro-mechanical devices
- Z 3 was programmed using punched 35mm film.
Alan M. Turing
- Led the WWII research group that broke the code for the Enigma Machine (fooled
Germans about invasion)
- Proposed a simple abstract universal machine model for defining computability: The ‘
- Devised the ‘turning hypothesis for Al.
IBM Harvard Mark 1
-The IBM automatic Sequence controlled calculator was installed at Harvard U.
-5ft. 5 tons, 750000 parts, 72 accumulators, 60 sets of rotary switches
Mauchly & Eckert
- headed the ENIAC team (Electronic Numerical Integrator And Computer) :general
- Commissioned by the Army for computing ballistic firing tables
- Decimal internal coding
- Manual programming of boards, switches and functional table.
Jon Von Neumann
- Prepares a draft for an automatic programmable device called EDVAC (stored
- Designed the Institute for Advances Studies machine, which became operational in
- -Binary, fetch decode execute. History:
Great Britain had a ‘stongehenge’, which seemed to be an early form of the calendar.
The ‘abacus’ 1600B.C. used to record numeric values
1700 Blaise Pascal built a gear driven machine, which performed whole number addition
1700 Gottfried Vilhelm von Leibniz built a mechanical machine to do addition subtraction
multiplication and division (not reliable)
1800 Joseph Jacquard designed a weaving cloth machine, which used cards with holes.
‘The punched card’
1900 Charles Babbage designed analytical engine. Too complex but his image is
incorporated into many modern computers. (Memory, input of both # and steps)
Ada Augusta is credited as the first programmer
Willaim Burrough made and sold an adding machine
Dr. Herman Hollerith developed a electro mechanical tabulator which read info from
1936 Alan Turning invented an abstract math model called turning machine.
Jon Von Neumann made a machine called EDVAC which was completed in 1950.
1951 first commercial computer
First Generation: 1951-1959
Commercial computers were built using vacuum tubes to store information
The vacuum tubes generated lots of heat and not reliable
Memory device: magnetic drum