Agenda 8

Winter 1998 Computers and Society
GST 2710, Section 90571
AGS 3360, Section 95198

Last updated: 3/3/98
Link back to course Welcome...

Eighth class: Tuesday, March 3
Agenda

Announcements:
1. The Midterm is two hours in class, next week, March 10.
2. If you miss a class, you are expected to go to the course Web Site, print out the materials for the class, and review them before the next class. Course Web Site is http://www.cll.wayne.edu/isp/drbowen/casw98. See Agenda for the Fifth or Sixth classes.
3. Be sure that you have the Midterm Topics handout. These are for discussion during the next class. There will be a review session for the midterm. This will be a "Q & A" review, in response to your questions.
4. Sign in via the Web at course Web Site.
5. Also see the course comments form on the Web Site. There was a request there for a review of pixels, so we will do that tonight.
6. The week of March 16 is the University's Spring Recess, so no class on Tuesday, March 17. I will, however, be in the computer lab for office hours from 4 - 6 PM. (This does not mean I will have the Midterms graded by then -- it's my vacation too!)
7. Assignment 6, CIO Pg 111, question 1. The biggest reason for parallel data transmission is speed. If you hear about a 16-bit computer, a 32-bit computer or a 64-bit computer, this is the number of parallel connections for sending data around (at least inside the microprocessor). 64 wires are 64 times as fast as one wire (serial). However, for communications between computers, the biggest reason for using serial communications (COM1, COM2, etc.) is the existence of a standard for the communications - RS232C. This is accepted by all manufacturers today, and means that any two computers can agree on how they will send data. For example, RS232C says that you will always send the leftmost bit first, and work your way down in order to the rightmost bit (1's bit) last. There are some problems with the standard; you have to use the right cable, but there are only two types, so if one doesn't work, try the other. (The issue is whether pin 2 on one end of the cable goes to pin 2 on the other end, or to pin 3, and the reverse for pin 3.) In parallel communications, different computers put the bits on the wires in different order, so they would have a real hard time communicating a number and agreeing on its value, using parallel communications. There could be a parallel communications standard -- there is a standard for PCs and printers -- but, for communications between computers, there is not a standard. PCs, for example, do not even put the bits on the wires in order.
8. Assignment 6, CIO Pg 112, questions 5 & 6. The point here is that there will presumably be a long sequence of these letters. Better examples for adults would be the series of minutes if you are a church secretary for a committee, or a series of invoices if you are in Billing for a company. Here, you may need to go back and retrieve the file for corrections or followup. So you need a file naming scheme that can help you find the right file quickly. The best suggestion was to create a separate directory for each different type of document, and put the needed information in the file name. For letters, name the directory, say mdlett, and in that directory name each file with the date. Something that I have found improves on this is to put the year first, then the month, then the day, like ag980227 for the agenda for class on February 22. This way, the documents show up in an alphetical list in date order, with the most recent at the top. If a document is monthly, like minutes of a monthly meeting, you do not need the day, so you could make add more letters, like min9801 for January 1998 minutes.
9. Many people have had trouble formatting and printing documents. This is apparently due to bad page setups. Even when the page setup is corrected, it still comes back. For now, when you start using Works for Word Processing, for each document, please check or make the following settings:
  1. File / Page Setup / Margins. Hint: try "Reset" button, but if things are really wrong, that may not work. Check Top and Bottom margins = 1", Left and Right margins = 1.25"
  2. File / Page Setup / Source, Size and Orientation. Hint: try "Reset" button, but if things are really wrong, that may not work. First check that Paper Source is "Default Tray". Then, that Paper Size is "Letter". Then, that Orientation is "Portrait". That should leave Width = 8.5" and Height = 11".
  3. Format / Paragraph / Indents. All three indents at 0".
  Please let me know if you have trouble implementing these settings, or if they keep getting undone. I think the problem was in the file prospectus.wps, and that, once you fix it, it should stay fixed.
Handouts, sign-in sheet, pass backs
Mouse actions. Earlier, on Agendas 1 and 2, I described the basic mouse actions in ways that were really not descriptions, but in some cases said what you can do with a given action. Both aspects are important. Here, for the record, are both. I will not ask you on tests or quizzes to describe everything you can do with each action. One or two examples will be fine. But it is important to understand the difference between a description of an action and a list of what you can do with an action. Understanding what you are being asked for is part of careful reading.
1. Point
  1. Description: Move the sensitive part of the mouse icon to the desired feature. (The sensitive part of the arrow icon is the very tip of the arrow.)
  2. What can you do with it:
    1. Set-up for other actions
    2. In many programs, pointing to a button displays a description of what the button does. In MS Works 3, for example, the description appears at the bottom of the Works window.
    3. In many programs, the mouse cursor changes shape as you point to different areas, indicating what you can do in that area. (For example, the "I-beam" shape indicates that you can insert text, while the arrow shape indicates that you can activate a button or select items by clicking on them. In MS Works, there are separate mouse cursors for dragging to resize and move)
    4. On the Windows 95 Start Bar, pointing to an item displays the choices for that item (in a bar to the right)
2. Click
  1. Description: point and click button once. (On standard Windows two-button mouse, "click" means click the left [normal] button, "right-click" means click the right button.)
  2. What you can do with it:
    1. Activate buttons, menu items
    2. Click on the title bar of an open window to make it the active window (for example, if you have several Works documents open, typing goes to the active window with the blue title bar.)
    3. Select icons, items in lists, and editable features such as shapes in MS Draw or applet features such as drawings in Works.
3. Double-click
  1. Description: point and click twice, rapidly. (The required speed can be configured using the Windows Control Panel)
  2. What you can do with it:
    1. Activate items that are selected with a single click (icons, items in lists and applet features such as drawings.)
4. Drag
  1. Description: point, click and hold, and move mouse icon with button down
  2. What you can do with it
    1. Drag window title bar to move window
    2. Drag window border to resize window. Also used with drawings, and with rows, columns and cells in spreadsheets and databases.
    3. Drag over items such as text in a word processing document or drawing objects in MS Draw to select them
    4. Drag 'N Drop to move selected items such as files in Windows Explorer, drawing objects such as lines in MS Draw, or selected text or features in MS Works and other word processors, spreadsheets and databases.
Review of pixels
1. What is a pixel? It is the smallest area or element of a digital picture -- a "dot" on the screen, for example. A picture is made up of pixels, with each pixel having its own color.
  NOTE: This is the case for "bitmap" images, such as screen and printer displays. In bitmap graphics programs, you also paint the bitmap directly. For "vector" drawing programs, you work with graphical shapes or objects, such as circles, lines and squares. To display or print the image, however, a vector graphics program must paint, or "render" a bitmap image.
2. Computer images are rectangular, so many pixels wide and so many high. Each pixel has its own binary color data. Each pixel has the same number of bits or bytes of color data, which determine how many different colors there can be in the image. For example, if the color data is one byte per pixel, then the byte can hold 256 different values (from 0 to 255), so there can be a maximum of 256 different colors in the image. Each value represents a different color. These product of these two parameters -- the number of pixels in the image and the number of bytes of color data per pixel -- determine the basic file size for the graphic. Most computer graphics are compressed, which reduces the file size.
3. How many bytes for a page of graphics?
  1. Pixels, Pixels per Inch (resolution), Bytes per Pixel (color depth), compression
  2. File size in bytes = Area (in²) * (Pixels / inch)² * (Bytes / Pixel) * (Compression factor)
    1. Black and white is one BIT per pixel (1/8 byte)
    2. Greyscale is typically one Byte per pixel - how many different shades of grey?
    3. 8-bit color - how many different colors?
    4. 24-bit color (true color) - how many different colors?
  3. Printer resolution in dots per inch; dot means the same as pixel
  4. Examples:
    1. Pages (8.5" x 11", 75 dots per inch) of 8-bit color graphics on a floppy diskette
    2. Pages (8.5" x 11", 300 dots per inch) of 24-bit color graphics on a 4 GB hard drive
    3. File size for a 3" x 2" graphic @ 300 Pixels per Inch, 3 Bytes per Pixel
  5. Animation
Computer operating systems
1. What do you need to do in a windowing GUI interface?
  1. Open / close
  2. Move
  3. Resize
  4. See list of open windows and activate one
2. What do you need to do with files?
  1. List
  2. Select
  3. Copy
  4. Move
  5. Delete
  6. Open
  7. Create / delete folders or directories
Internet
1. A network of networks (review)
  1. TCP/IP protocol routes packets between computers. Computers called "Routers" do this job.
  2. Every computer has a unique numerical "IP addresses" of the form a.b.c.d where each character is a byte (0 to 255). This allows over 4 billion addresses, but we are running out. "Next Generation" (IPv6) will have more. Will most likely provide security and encryption also, for privacy
  3. Computers can be given domain names by "Domain Name Servers" (DNS). Domain names look like www.cll.wayne.edu. DNS computers translate back and forth between domain names and IP addresses.
  4. The Internet itself has no idea what type of information is travelling over it -- like a trucking firm not knowing what is in the packages
2. Client / Server
  1. Server: central computer that provides information in response to requests. Also runs server software.
  2. Client: user program that requests information, receives and displays it . Also runs client software.
  3. Generally, the client must log in to the server. (Exception is World Wide Web)
3. Example 1: email
  1. Server identifies Internet email account as UserID@computer. Example: drbowen@cll.wayne.edu. The Internet knows how to find "computer." "computer" is the Mail Server and must know how to find UserID.
  2. Client requests / sends email via Mail Server
  3. Internet itself has no idea that the traffic is email. The nature of the traffic is determined by the client and server.
  4. If clients and servers agree on how to send and receive email messages, different clients can work with different servers. Example: Eudora, Netscape and Internet Explorer can all send / receive email with POP email servers. POP = Post Office Protocol. New Eudora and Netscape can also send / receive with IMAP protocol (Internet Mail Access Protocol).
    1. Protocol -- in computerese, a standard that is accepted for transferring a certain type of information between computers.
    2. (MIME - Multipurpose Internet Mail Extensions, include protocols for related email functions, such as attaching a file to a message. For example, a word processing file or a sound or video file.)
4. Example 2: Telnet
  1. A Telnet client sends its keyboard input to the Telnet server. The server treats this as if it came from its own keyboard.
  2. The server sends its monitor output to the client, which sends this to its own monitor.
  3. In this way, the client controls the server. Anything that the server computer can do, can be done remotely via the client.
  4. Telnet servers have the ability to limit what the client has authority to do.
  5. At this point, Telnet is for command-line interface operating systems
  6. We will use Telnet for email. The Telnet client will control an email client on the same computer as the mail server (mail.wayne.edu).
Logic Gates - see Worksheet: Logic Gate
Databases in Works
1. What is a database
  1. Storage of information in fields and records
  2. Tools for managing the information
    1. Search
    2. Sort
    3. Reports
    4. Queries
    5. Hide/Show records
2. We will be working with small databases in this class. The need for some of the database tools is not obvious until you understand that many databases have millions of records.
Lab
1. Work through MW Pp 50 - 66 on databases.

Assignment - get ready for the Midterm next week (March 10).