CT Seeram Chapter 2: Introduction to Computers

Electronic Computer Technology Vacuum tubes Discrete Semiconductors Integrated Circuits

Early Computers Vacuum tube memory Input / Output Punch cards Magnetic Tape

Electronic Computer Technology Warm-up hot Ran hot tube filaments required constant heating computers required air conditioning Frequent failures

Computersafter Vacuum Tubes Transistor & magnetic core memory Smaller Less power needed

Discrete Semiconductor Components in Computers transistors magnetic memory cores Space requirements large but smaller than vacuum tubes cooler Ran much cooler than vacuum tubes

Computers: The Big Jump Integrated Circuits millions of semiconductor components in tiny package lower production costs Extremely small Extremely fast Run very cool Very reliable

Categories of Computers Super computers Mainframes Minicomputers Microcomputers

5 th Generation: Supercomputers Large (even today) Expensive Found only in major research sites Applications weather scientific modeling oil exploration other research

Mainframe Computers Large $$$ Requires teams of experts Large # of users Applications large corporations government hospitals

Microcomputer “PC” Rapidly changing technology Low cost Non-proprietary First common in 1980’s

Minicomputers First seen in 1970’s Much less expensive than mainframes Medium-sized Proprietary ($$$) parts operating systems Computer used for CT Appropriate Size price Applications imaging, reconstruction archiving

Basics InputProcessingOutput

Input Manual keyboard mouse Electronic CT detectors CR Plates Input ProcessingOutput u Other u Voice recognition

Analog to Digital Conversion (A to D) Analog (continuously varying) Digital (discretely varying)

Analog to Digital Conversion (A to D) Many real world inputs are analog voltages CT detector intensity Analog values must be converted to a # to use in a computer Input analog voltage 1234 Digital conversion to computer

Processing Central Processing Unit (CPU) Arithmetic Logic Internal Memory Scratchpad Input Processing Output

Hard copy printer Soft copy CRT InputProcessing Output u Storage disk tape

Hardcopy Devices Do not lose information when power is shut off Printers impact (dot matrix) noisy multi-copy non-impact (quiet) ink jet laser Plotters Microfilm

Softcopy Devices Lose all information when power shut off Flat-panel monitors

Digital to Analog Conversion (D to A) Computer reconstructs digital image set of numbers Computer displays analog image

Computer System Elements Hardware Software People

Hardware Computer Peripherals keyboard printer Hardware Software People

Hardware Examples Disk Drive Memory Random Access (RAM) Read only (ROM) Mouse Keyboard Cables Hardware Software People

Software Instructions to computer Operating System Applications Hardware Software People

Operating System Fundamental instructions to hardware What to do when computer first turned on How to interact with hardware CRT Keyboard Mouse Modem Hardware Software People

Operating System Computer “face” presented to users Windows DOS MAC OS Dictates how users interact with computer to run application software Hardware Software People

Application Software Computer instructions which perform some desired task Balance checkbook Play a game Calculate (reconstruct) a CT image Hardware Software People

Application Software quasi-English Usually a quasi-English language Basic Fortran COBOL C Languages provide tools to software developers to efficiently design application software Forms![FDoSurvey]![FExpsSub].Form![KVEff] = Val(Mid$(MyData, 2, 10)) Forms![FDoSurvey]![FExpsSub].Form![KVAVG] = Val(Mid$(MyData, 12, 10)) Forms![FDoSurvey]![FExpsSub].Form![MRMEAS] = Val(Mid$(MyData, 22, 10)) Forms![FDoSurvey]![FExpsSub].Form![TIMEMEAS] = Val(Mid$(MyData, 32, 10)) DumText = Mid$(MyData, 42, 3) 'MsgBox$ (DumText) If Right$(DumText, 1) = "+" Then DumText = Left$(DumText, 2) Else DumText = Left$(DumText, 1) End If 'MsgBox (DumText) MyData = Right$(MyData, Len(MyData) - Len(DumText) - 41) 'MsgBox (MyData) NKvs = Val(DumText) 'MsgBox (NKvs) KVMAX = 0 If NKvs > 0 Then For DumNum = 1 To NKvs 'MsgBox (Val(Mid$(MyData, 10 * (DumNum - 1) + 1, 10))) If (Val(Mid$(MyData, 10 * (DumNum - 1) + 1, 10))) > KVMAX Then KVMAX = (Val(Mid$(MyData, 10 * (DumNum - 1) + 1, 10))) End If Next Forms![FDoSurvey]![FExpsSub].Form![KVMAX] = KVMAX End If DoCmd.Close acForm, "FNeroExp" End Sub

People Designers hardware software Users run applications provide input use output

Meaningless Slide

Storage Hardware Random vs. Sequential Direct (random) access any data can be accessed at any time disks Sequential access data only accessed in serial fashion must pass through unwanted data to reach target data tapes information encoded magnetically

Data Storage Technologies (constantly changing) Disks Formats Hard removable non-removable Floppy CD CD-RW CD-R Tape lots of data serial access u Technologies »Magnetic (disks & tape) u re-writable »optical (disks & CD’s) u re-writable u write once

Data Communication Features speed cost topology wiring scheme u Data transmission between computers

Data Communication Technologies Telephone lines twisted pair wires Coaxial cable Fiber optic cable Microwaves Satellites Radio waves

Networks LAN (Local area network) computers connected in one area LAN’s can be connected together WAN (Wide area network) computers connected together over large distances Communications protocols Ethernet uses bus technology Internet

File Server Special computer which handles functions for connected computers disk access printing Incorporates security may limit user to selected files or directories may limit # of connections per user may limit times when network available

Typical Lan Network Gateway Other Networks

Radiology Computer Systems RIS Professional Billing CR CT MRI Digital Dictation Mammography Digital Spot Film Voice to Text Dictation Web Server Insurance Carrier Hospital Admission/Discharge Billing Reports PACS Angio / Digital Subtraction

The Computerization of Radiology RISPACS CTCRMRI Digital Fluoro Digital Angio DictationAdmin Radiologist Workstation Radiologist Workstation Radiologist Workstation 3D Workstation Nuc Med Laser Printer Web Browser

The Internet Network connecting all computers Originally developed for security Single bomb can’t destroy all U.S. computing facilities Can connect large number of computers in many locations Communicates in finite “packets” Each packet has specific destination (address) Packets can be Web site linking Allows linking of information