LECTURE 2 - COMPUTER HARDWARE

Modern computer design is "one out of many" - could have been different

Computers are just a bunch of switches - may be electric or mechanical

Tinker-toy computer (a working computer that can play tic-tac-toe built by MIT students in the 1980s out of Tinker-toy components and turned with a crank
http://www.rci.rutgers.edu/~cfs/472_html/Intro/TinkertoyComputer/TinkerToy.html

Electronic computers use binary counting

• A "bit" is either off "0" or on "1"
• Requires computer to count using base 2, opposed to usual base 10
• One byte -  8 bits
• Computers also use "word" 16-bit, "long word" 32-bit, "double" 64-bit in computing
• Some systems also "count" using "hexadecimal" (base 16) and "octal" (base 8)

Encoding of alphanumeric characters using bytes

00000001 = 1 (base 2 counting)

00001000 = 8 (base 2 counting)

00110001 = 49 base 2 counting, or keyboard "1" (using ASCII code)

01000001 = 65 base 2 counting, or keyboard "A" (using ASCII code)

ASCII CODE TABLE
http://www.neurophys.wisc.edu/www/comp/docs/ascii.html

Basic theory of modern computers developed by Alan Turing	John von Neumann developed a practical physical architecture for digital computers (1946). All computers today use a variation of von Neumann architecture http://www.idemployee.id.tue.nl/g.w.m.rauterberg/presentations/HCI-history/tsld007.htm

Elements of von Neumann computers:

• A single data store of addressable memory elements containing both the information to be operated upon and the instructions specifying the operations to be performed.
• A program counter designating the instruction currently being executed.
• Logical circuits executing the current instruction
• Some sort of machinery which changes the data store as specified by the current instruction,
• Machinery which resets the program counter to point to a new instruction

von Neumann architecture of a typical personal computer. A clock is connected to a "bus" bundle of wires which causes synchronized flipping of switches inside each component of the computer.	Basic von Neumann memory architecture. Data (program code and data) are stored separately from the primary processors, collected into the "central processing unit" or CPU. Data is relayed back and forth on a "bus". In addition, program code (software) and data are stored separately.
Arrangement of von Neumann design in a Personal Computer (PC) using modern microprocessor components. These components are typically wired together on a single "mainboard" or "motherboard"	von Neumann architecture in a single-chip computer (used in portable computing)

Types of computers today

Mainframe/Mini-mainframe	Supercomputer (1000s of workstation-level PCs together)
Desktop workstation (high-performance PC, optimized for business use)	Gamer computer (high-end PC, 3D graphics optimized, power-hungry, needs extra fans to blow off waste heat)
Low-end personal computer (bundled computer/monitor, may use non-windows OS, low-power, ok for web surfing and email)	Media center PC/"set top box" (uses remote instead of keyboard, high-quality audio output, can accept/process video signals from cable, output to TV, VCR, DVD, "search engine" for programs, video on demand, Digital Rights Mangement (DRM), connect to "home network, record television for later viewing)
Notebook computer (same programs as general PC,	Dedicated game console (Xbox 360)
PDA (business use, can't run PC programs, has own OS and programs, pointing stylus, mini-keyboard, sometimes cellphone capacity)	Portable game console (dedicated game graphics, some PDA functions
Single-board computer (equivalent to PC from 10 years ago, no user interface, used to control complex devices, e.g. automobile engines)	Smartphone (cellphone with PDA computer functions and PDA OS, camera, GPS, sensors)
Basic cellphone, simple OS, some computer functions, camera	SPOT watch (one-way reception of data, calendar, time functions)
Multimedia "gadgets" (IPod) - special-purpose media processing computers	Multimedia "gadgets" (portable DVD player/recorder) - special-purpose media-processing conputers
dedicated microprocessor	Microprocessor on circuit board (embedded device like microwaves, parking meters)

What computer circuits are made of

• Computer circuits = a bunch of switches that can switch each other on and off
• Pre-1960s computers
  • Vacuum tubes, then transistors were used to create logic circuits
  • led to "complexity explosion" - wiring too complex
     

    vacuum tubes in early computer	transistor radio

     

• Invention of the Integrated Circuit (IC)
  • discovery that ALL electrical systems could be made out of silicon and placed on a single flat silicon "chip"
  • inefficient, bad energy use, but vastly simplifies construction
  • Created by Jack Kirby and Robert Noyce in 1959
    http://www.pbs.org/transistor/background1/events/icinv.html
    
• First complete "computer on a chip" 4004 "microprocessor"
  • Intel 4004 microprocessor ~ 1971
    
  • Pentium IV microprocessor ~1 million times more complex than 4004
    

How ICs are made

• Photo-micro-lithography (concept borrowed from printing)

Factors controlling speed of ICs

• Material - silicon, germanium
• Clock speed - determines how fast switches can switch in von Neuman machine
• Size of circuits - small ones switch faster that big ones
  • Current generation - 90 nanometers to 45 nanometers

Limits to ICs - estimated "endpoint" ~ 2010

• Power - if circuits are too small, electricity "bleeds" between components
• Atomic limits - can't go below the width of about 10 atoms (~5 nanometers)
• Sensitivity - Smaller circuits become ever more sensitive to electrical, mechanical disruption (why NASA uses old microprocessors in its spacecraft)
  • Hardware specs of the computers on the Mars Rovers
    http://www.space.com/businesstechnology/technology/mer_computer_040128.html
• Resistance - More electrical power needed to force current through microscopic wires

Build your own - Computer components

CPU - AMD Athlon processor (64-bit)	CPU - Intel Pentium 4 processor (64-bit)	Nvidia GeForce Graphics Card (GPU)
AMD 64-bit System Board	Intel "Prescott" System Board 32-bit	Intel 64-bit System Board
Tyan Quad-dual processor system board (total of 8 CPUs)	Types of System memory (RAM)	Flash Memory (MMC, SD, in Thumbdrive)
Hard disk inside	Hard disk case	Tiny Hard drive for portables
RAID (redundant array of hard disks)	Fan for cooling CPU	Hard drive cooling fan
Liquid cooling system for mainboard	Graphic card cooler	Typical computer power supply

Monitors and display devices

CRT (Cathode Ray Tube) monitor	LCD (Liquid-Crystal Display) Monitor

Connecting computer components
http://www.refurbished-laptops.biz/laptop-ports/

Cables - IDE (parallel) for hard drives	Cables - SATA (serial) for hard drives
Ethernet cable (compared to phone cable) for Internet connections	USB (Universal Serial Bus) cable (hard disks, thumbdrives, keyboard, mouse)
Firewire (I394, digital video, 6 and 4-pin configurations)	PS/2 connector (keyboards, mouse)
PCMCIA (hard disks, modems, wireless Internet on portables)	IRDa (Infra-red wireless connections for modems, cellphones)
Serial port cable (modems, joysticks)	VGA Monitor (most monitors)
Parallel port cable (inexpensive printers)	S-Video plus audio cables (output signal to television, VCR, DVD)
	Wifi card installed in PC
Flash memory (thumbdrive) with Bluetooth

Networking

Flash memory (thumbdrive) with Bluetooth	Bluetooth wireless phone headset
WiFi hub	Apple AirPort wireless hub and connector
WiFi PCMIA card (portable)	WiFi card in PC

COMPUTER SOFTWARE

Programming

The art/science of writing code that, when executed by a computer, will form a useful function

History of programming languages
http://perso.wanadoo.fr/levenez/lang/ \

Brief history of programming languages
http://www.byte.com/art/9509/sec7/art19.htm

Levels of programming for computers

NOTE - each "level" becomes 10-100 times slower than the previous one as writing software is made easier

• Machine language
  • logical "True" and "False" instead of "1s" and "0s" - Grace Hopper wrote it, but nobody does anymore (too hard)
• Assembly language
  • Several machine language operations are executed by a single assembler command
  • Typical command - move a data byte from memory into the CPU
  • Used to write "rendering" algorithms (video compression, Photoshop filters)
  • Used to program special-purpose microprocessors (e.g. parking meters)
  • Example for assembly/machine language (addition and subtraction)
    
• High-level programming languages
  • Thousands of assembler operations executed by a single high-level command
  • Examples
    • C++ - used to write most PC software, develop game engines
    • Visual Basic - used to write specialized applications for Windows computers
    • Java (NOT JavaScript) - used in set-top boxes, media centers, some complex websites
    • Web-based "markup" languages (HTML, CSS) - let designers "draw" web pages
    • Web-based programming languages (PHP, ASP.NET, Ruby) - allow interactivity through the Internet
    • Example for Visual Basic (opens a connection to modem or joystick)

    Private Function openOneSerialPort(ByVal portCount As Integer, ByVal baudVal As Integer) As Boolean
     Try
        panelGlobalSensors(portCount).activePort.BaudRate = 9600
        panelGlobalSensors(portCount).activePort.DataBits =8
        panelGlobalSensors(portCount).activePort.Parity = Parity.None
        panelGlobalSensors(portCount).activePort.StopBits = StopBits.One
        panelGlobalSensors(portCount).activePort.NewLine = Chr(13)
        panelGlobalSensors(portCount).activePort.ReceivedBytesThreshold = 8
        panelGlobalSensors(portCount).activePort.Open()
      Catch ex As System.AccessViolationException
        Return False 'the port was still open - retry?
      Catch ex2 As UnauthorizedAccessException
     End Try
     Return True 'success in re-opening port
    End Function
     

• Authoring languages
  • Create visual metaphors for high-level language commands
  • Limited in power, but more easily mastered by non-programmers (you)
    • Spreadsheet languages (e.g. Excel)
    • Graphic design languages (e.g. "scripting" in Photoshop, Illustrator)
    • Visual design interfaces (e.g. Adobe Flash, Dreamweaver, LiveMotion)

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