CSCI 1200 Introduction to Computing for Non Majors CHAPTER 2 Tami Meredith, Ph.D.

 Generally understand how computers store and manipulate information.  Describe the basic structure, components, and organization of a computer.  Explain why a computer typically has different types of memory and storage devices.  Roughly understand binary numbers and Boolean logic. 2

Four basic operations:  Receive input: Accept information from outside world  Process information: Perform arithmetic (math) or logical (Boolean) operations on information  Produce output: Communicate information to outside world  Store information: Store and retrieve information from memory and storage devices 3

 Computers are super simple. All they really can do is: › Store something in memory, › Move it around memory, › Add two things in memory, and › Compare two things in memory.  Do these things very, very, fast! 4

Hardware components  Input devices  Output devices  Microprocessor (CPU) › Computation and processing  Memory/storage devices › Volatile storage › Persistent storage 5

 Information: Communication that has value because it informs versus  Information: Anything that can be communicated, whether it has value or not – Properly "data" 6

 Electricity flows from place to place through wires  If it is flowing, electricity is present and can be used (i.e., a light is on when electricity flows)  When it is not flowing, it is not present (i.e., a light is off)  We can create devices that store small amounts of electricity  These devices have two states: 0 = Off, nothing stored, no electricity 1 = On, something stored, electricity present 7

 Binary is an alternative number system that has two digits, 0 and 1  Computers can store binary numbers using electricity (0 = off, 1 = on)  Binary is equivalent in ALL ways to decimal (base 10) numbers, except it's easier for computers to work with 8

 Base ten is based on powers of = (4*1000) + (2*100) + (0*10) + (6*1) = (4*10 3 ) + (2*10 2 ) + (0*10 1 ) + (6*10 0 )  Base two is based on powers of = (1*8) + (1*4) + (0*2) +(1*1) = (1*2 3 ) + (1*2 2 ) + (0*2 1 ) +(1*2 0 ) = = 13 in base ten 9

 Bit: From B inary dig it › Smallest unit of information computer can process › Can have one of two values: 0 or 1 › Holds a single digit of a binary number  Byte › Collection of 8 bits (8 digit binary numbers) › Can represent 256 different numbers › That is because 2 8 =

 Denotes all numbers with combinations of 0s and 1s  Decimal numbers automatically converted to binary  Binary number processing hidden from user 11 DecimalBinary

 Bits can also store codes that represent each letter, digit, and special character  ASCII: Most widely used › Each character is a unique 8- ­bit code › 256 unique codes for 26 letters, 10 digits, special characters  Unicode: Supports more than 100,000 unique characters 12

 ASCII character set was originally designed to include only English-language characters from 0 to 127 (Extended ASCII added accents)  Unicode’s international standard character set allows for about 120,000 distinct codes to include Chinese, Korean, Japanese, and Arabic characters 13

Kilobyte (KB) = 2 10 bytes = 1024 bytes Megabyte (MB) = 2 20 bytes = bytes Gigabyte (GB) = 2 30 bytes = ~1 Billion Terabyte (TB) = 2 40 bytes = ~1 Trillion Petabyte (PB) = 2 50 bytes = ~1 Quadrillion 14

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 A digital computer is a collection of on/off switches designed to transform information from one form to another.  The user provides the computer with patterns of bits— input —and the computer follows instructions to transform that input into a different pattern of bits— output —to return to the user. 16

 CPU often called “processor”  Performs transformations of input into output  Interprets and executes instructions in programs  Performs arithmetic and logical data manipulations  Communicates with other parts of the computer system indirectly through memory 17

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Modern Microprocessor › Complex collection of electronic circuits › CPU housed with other chips on circuit board › Circuit board containing computer’s CPU is called motherboard 19

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 Choosing a Computer › Type of CPU is important part of decision › Important factors to consider:  Compatibility  Performance  Heat properties/cooling  Power consumption  Cost 21

 Not all software is compatible with every CPU.  Every processor has built-in set of instructions.  CPUs in same family are generally backward compatible. › Designed to process instructions handled by earlier models  AMD processors made to be compatible with Intel.  Compatibility also requires the same operating system (e.g., OS-X, Windows, Linux) 22

 Some processors faster than others  Performance is determined by: › Speed of internal clock —measured in gigahertz (GHz) › Architecture of processor › Number of bits processor can process at one time; typically 64 bits—called word size  Heat generated increases with clock speed, amount of computation in process, and density of transistors 23

 Multicore Processors  A "core" is a semi- independent processing unit that's part of a CPU  Single chip contains multiple CPUs (cores) › Run simultaneously › Divide work › Most new PCs have at least two cores › 4, 6, 8 cores are comon 24

 Special Purpose Processors › Supplement basic CPU › Typical CPU contains graphics-processing unit (GPU) which handles:  3-D graphics rendering  Vector math (same thing done to many values)  Other visual calculations  GPUs are also on Graphics Card if you have one › Frees main CPU to work on other tasks 25

 Performance enhancing techniques aren’t confined to the insides of CPU chips.  Instead of adding more cores, a large system might simply add more machines to a network.  Parallel processing has been used in high- end servers and workstations for some time.  Threaded processing in multicore CPUs is like a microscopic version of parallel processing used in some of the world’s biggest computing networks. 26

 Typical CPU is divided into several functional units: › Control unit › Arithmetic logic unit (ALU) includes registers › Decode unit › Bus unit › Prefetch unit  These units work together to complete the execution of program instructions. 27

1. Fetch an instruction 2. Decode it to see what it does and needs 3. Fetch any data that is needed 4. Execute the instruction using the data 5. Store the result somewhere 28

 CPUs are based on Boolean Logic  Boolean Logic is a way of manipulating logical values  Two logical values: 0 = False, 1 = True  True/False = 1/0 = contents of a bit 29

 And: A circuit that produces the value of true (1) if both inputs are true (1) and it produces false (0) otherwise.  Or: A circuit that produces the value of true (1) if one, the other, or both of the inputs are true (1) and it produces false (0) otherwise (when both inputs are 0)  Not: A circuit that takes one input and produces the opposite by switching false to true or true to false (also called an inverter) 30

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Properties of Memory  Persistence: Persistent vs. Volatile › Will it store values when power is off?  Access type: RAM vs. ROM › Can it be written to or is it read only?  Speed: How long does it take to get a value from it to the cpu? 33

 Goes from small storage and fast access to large storage and slow access › Register: in a core, 64 bits each › L1/L2 Cache: in core, 64 KB, 256 KB › L3 Cache: in CPU, 2-20 MB › L4 Cache: on motherboard, 128 MB › Main Memory: on motherboard, 8-32 GB › Solid State Disk Drive: in computer, GB › Hard Disk Drive: in computer,.5 to 2 TB › DVD/CD (Optical Drive): in computer, 4.7 GB › Cloud Storage: on network, virtually infinite 34

 Random access memory (RAM) › Most common type of primary storage › Stores program instructions and data temporarily › Memory locations have unique addresses › Volatile—contents disappear when power is turned off › Used inside CPU, Cache, Main Memory 35

 Read-only memory (ROM) › Information is etched on chip when manufactured › Stores start-up instructions and other critical information (e.g., how to start windows)  Complementary metal-oxide semiconductor (CMOS) › Special low-energy persistent RAM that is used to store data used in starting the computer (has a tiny battery to power it)  Flash memory (Persistent RAM) › Can be written and erased repeatedly › Used for digital cameras, cell phones, handheld computers, USB sticks/drives › Slower access, replaces a disk drive, not main memory 36

1. When you turn on the computer, the CPU automatically begins executing start-up instructions (firmware from the BIOS) stored in CMOS ROM. 2. The start-up instructions tell it how to copy an initial program from disk into main memory. 3. That program, the "Bootstrap Loader" finds the correct operating system and copies it from disk to main memory as well. 4. Once instructions for the operating system are loaded into main memory, the CPU be is able to execute them and respond to user input. 37

 Information travels between components on the motherboard through wires called internal buses or just buses.  Buses: Bridges between components  Buses connect to: › Storage devices in bays › Expansion slots › External buses and ports 38

 Serial: One connection, signals are sent one bit at a time in series, one after another  Parallel: Many connections, signals are sent one word at a time in parallel, at the same time 39

 Computer has variety of ports to meet diverse needs › Video ports to connect monitors – HDMI, DVI › Audio ports to connect speakers and/or headphones › Network ports to connect to a network – ethernet › Disk ports to connect to a disk drive – SATA › Multipurpose USB ports to connect keyboards, mice, printers, cameras, disk drives, portable storage devices, and more  Some ports connected directly to system board  Others connected to expansion cards that fit in expansion slots on the motherboard 40

 Slots and ports make it easy to add peripherals to computer system.  Some peripherals, such as keyboards and printers, serve as communication links between people and computers.  Other peripherals link computers to other machines.  Still others provide long-term storage media. 41

 A computer manipulates patterns of bits represented by two symbols: 0 and 1.  Bits can be grouped into coded messages that represent alphabetic characters, pictures, colors, sounds, and other kinds of information.  The microprocessor follows software instructions to perform calculations and logical manipulations that transform input data into output. 42

 Not all CPUs are compatible with each other.  Modern CPUs employ multicore or many core processing systems that speed calculations.  The CPU uses RAM (random access memory) as a temporary storage area.  ROM (read-only memory) contains unchangeable information. 43

 The CPU and main memory are housed in silicon chips on the motherboard and other circuit boards inside the computer.  Buses connect to slots and ports that enable the computer to communicate with internal devices and external peripherals. 44