Understanding Hardware and Software in Computing Systems

[Ch-1] Hardware = [Physical](iPhone) - vs - Software -- (iOS) = [Programs with instructions] -- [Layers of a Computing System] - (C.A.O.P.H.I) Communications -> Applications -> Operating Systems -> Programming -> Hardware

Information -- Abstraction - [a mental model that removes complex details] - Applies to (Miller's Law) [the average person can hold in working memory about seven items] Internal View = car engine, while Abstract View = driving -- Stonehenge, Wiltshire, England 3000 BC to 2000 BC -- Abacus - [early device to record numerical values] - Blaise Pascal - [Mechanical device for addition, subtraction, multiplication, and division] -- Joseph Jacquard - [Loom, punched card], Charles Babbage - [Analytical engine] -- Ada Lovelace - [First Programmer, the loop], Alan Turing - [Turing Machine] - Harvard Mark I, ENIAC, UNIVAC I - early computers, physics & engineering -- (1st Gen. Hardware) - [1951-1959] [Vacuum Tubes, Magnetic Drum, Card Readers -> Magnetic Tape Drives] -- 2nd Gen - [1959] -> Transistors, Magnetic Cores, Magnetic Disks - 3rd Gen - [1965] - [Integrated Circuits, Transistors, Terminal] - 4th Gen - (1971-now) - [Large-scale integration, PCs, workstations, laptops, smartphones] -- Computing and Networking -> Parallel Computing & Internet -- (1st Gen Software) - [1951] - [Machine Language -> Assembly Language & translators -> Programmer Changes] - (Assembly/Machine) = [Machine Language is input to Assembler & becomes Assembly Language] -- (2nd Gen) - (1959) High-Level languages introduced - [Machine Language -> Assembly Language -> High-Level Language] -- (3rd Gen) - (1965) - [Systems Software, Separation between Users and Hardware] -- [Machine Language -> Assembly Language -> High-Level Language -> Systems Software -> Application Packages] -- (4th Gen) - (1971-1989) - [Structured Programming, New Applications for Users] -- (5th Gen) - (1990-now) - [Microsoft, Object-Oriented Design, World Wide Web, New Users] -- [Moore's Law] - (1965) - "the number of transistors on a chip will double every 2 years" ---- Ch 2. [Decimal numbers 0-9 = 10 digits], Binary is base 2 and is [0, 1], - [Hexadecimal -> Base 16 = digits: 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, A, B, C, D, E & F] -- Converting Octal to Decimal, Converting Hexadecimal to Decimal, Converting Binary to Decimal, Arithmetic in Binary 1 + 1 is 0 with carry. Converting Binary to Octal (Convert groups of three from the right), Converting Binary to Hexadecimal (Convert groups of four), Converting Decimal to Hexadecimal, Low voltage = 0 <-> High voltage = 1 (all bits have 0 or 1) (Byte = 8 bits (word length of the computer), 32-bit machines, 64-bit machines, etc.) -- Ch 3 - Multimedia Devices - [Numbers, Text, Audio, Images, and Video] - Data Compression - Compression Ratio = compressed data/original data - Lossless Data - ZIP File VS Lossy Data like JPG image -- Analog Data - Continuous representation of actual data - (Digital Data) - [Discrete representation of data (Digitize - breaks information up) - Reclocked - (Digital Signal is reclocked) to regain original shape - [Overflow] - 1 + 1 = 0 (when the computed value doesn't fit) Character Set: (a list of characters and the codes used to represent each one) -- [ASCII] - (American Standard Code for Information Interchange) - used seven bits to represent characters, allowing 128 unique letters) Extended ASCII evolved with 8 bits. - (The first 32 of ASCII are not characters; they are commands) Unicode mapping uses 16 bits per character -- Unicode is a superset of ASCII; the first 256 characters correspond to ASCII - Text Compression assigns 16 bits to each character -- Keyword Encoding (replaces frequently used words with a single character) Run-length Encoding (a single character may be repeated over and over again in a long sentence) -- [Huffman Codes use variable-length bit strings to represent each character] Huffman Code 00 -> Character A] To decode - look for a match left to right, bit by bit, record letter. -- Stereo-electric signal to speaker = sound, analog representation = sound wave, voltage varies in sound wave. Sampling is lossy. RGB Colors (0, 0, 0) = black, (255, 255, 255) = white, HiColor 16-bit, True Color 24-bit.