Transcript Using the Computer

Using the Computer
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Turning it on – Your computers in the lab should be turned on, but
if you arrive and the screen is blank, do the following:
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Turning it off (do one of the following and follow the instructions)
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Hit the return key to make sure the machine is not in power-saving
mode
Ask the lab instructor if the machine is turned off for a reason, like
repairs
Make sure it is plugged in.
Press power button for the computer – probably in the middle front of
the tower.
Press power button for the monitor – probably below the screen.
Use the START button and select SHUT DOWN.
Use ALT-CTRL-DELETE
Unplug it
Breaking it
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You can’t break the machine by typing anything wrong or turning it off
or on.
You can break it by forcing floppy discs into the wrong places.
Using the Computer
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Turning it off – you shouldn’t have to do turn the machine off
during lab unless it stops responding completely. You will want to
log off at the end of lab, though. Do one of the following and
follow the instructions the machine provides.
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Click the START button (lower left corner of screen) and select SHUT
DOWN. Then select “shut down”, “restart”, or “log off” from the
menu.
Use ALT-CTRL-DELETE then follow directions (particularly if the
machine has stopped responding)
Unplug it – last resort, ask lab instructor first.
Breaking it
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You can’t break the machine by typing anything wrong or turning it off
or on.
You can break it by forcing floppy discs into the wrong places.
Using the Computer
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Breaking it – its pretty hard to break it.
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You can’t break the machine by typing anything wrong or turning it off
or on. So don’t worry about experiementing with your programs. A
good way to learn things like JavaScript is to say “I wonder what
happens when I do THIS.” and then go do it. The worst that can
happen is that you have to restart the machine.
Deleting important files. This is possible, but hard to do by accident.
You should always keep the lab machines free of your assignments.
Bring floppy disks to lab to store your files on, or transfer them to
Pegasus and then delete them from the lab machine. When you delete
files, the machine will ask you if you are sure you want to do it. Be
careful at this point – just verify that only the files you want deleted
are selected before you hit the “ok” button.
You can break it by forcing floppy discs into the wrong places.
Using the Computer
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Finding Files
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Use the “Find files” feature if you know the file name.
Click “Start” and then “Find”.
A quicker way (usually) is to traverse the directory structure using “My
Computer” icon. Double click on the icon and then maneuver your
way around the directory structure with more clicking. For the most
part, you will only need to go to the “A:” directory (the floppy disk)
and the Desktop.
Editing files
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The main thing is to remember that your files must be text only. In
other words, using MS Word with the default save settings will not
work. My favorite program for editing in a text-only mode is Notepad.
It comes standard on MS machines (usually click on Start, then
Programs, then Accessories then Notepad).
You may use any other editor you like, but make certain it saves in
plain text format.
Some Notes on Programming Languages
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Syntax – the mechanical way that programs can be
assembled
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Programming languages are very specific about syntax
This means that putting in a single quote ‘ where a double
quote “ should be can ruin your entire program.
Putting a square bracket [ where a parenthesis ( should be can
ruin your entire program.
This can be frustrating.
Capitalization almost always counts. Be conscious of things
like that.
Many things come in pairs (quotation marks, parenthesis for
example). Make sure that things that should be in pairs are.
If your program does absolutely nothing, you probably have a
small syntax error.
If your program does something, but its wrong, then you
probably have an error in your logic when you designed the
program.
Introduction to HTML
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HTML = Hypertext Markup Language Language
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HTML is
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A very weak computational language (basically nil).
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An interpreted language (interpreted by the browser).
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Designed specifically to tell browsers how to display web pages.
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Requires a browser for the page to be displayed.
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Can only suggest display preferences to the browser (this surprises a
lot of people).
Structure of HTML
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HTML uses tags to suggest how to display items on a page
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Most tags come in pairs:
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Learning HTML is really about learning how to use the tags.
Makes it easy to do useful pages quickly.
<tag> starts the action
</tag> stops the action
Example: <HTML> begins all html documents and </HTML> ends
them
Example: <center>Title</center> will center the word “Title” on the
page.
Some tags do not come in pairs:
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<br> is a line break, causing the display to continue on a new line
<hr> inserts a horizontal rule (line) across the page.
Structure of HTML
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Anything that is not specified by tags is displayed per the
browsers preference
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Adding extra spaces in between words won’t have any effect on the
page.
Putting things on a new line won’t have any effect on the displayed
web page (the <BR> tag does that).
Example:
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“Hello, World.” and “Hello,
World.” will look the same.
“Hello, World.” and “Hello,
World.” will both be shown on the same line.
Structure of HTML
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There are 4 tags required in any HTML document.
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<HTML></HTML> Tells the browser where the web page starts and
stops
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<HEAD></HEAD> Tells the browser where the informational portion of
the web page starts and stops
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<BODY></BODY> Tells the browser where the displayed portion of the
web page starts and stops
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<TITLE></TITLE> Tells the browser what title to display for this page.
Structure of HTML
<HTML>
<HEAD>
<TITLE>Example of HTML structure</TITLE>
Information hidden from the viewer.
</HEAD>
<BODY>
Visible web page.
</BODY>
</HTML>
“Hello, World!”
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There is a particular, simple program called “Hello, World!” that
many CS people use when first encountering a new language.
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“Hello, World!” prints the words “Hello, World!” on the screen.
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The idea is that if you can get this simple thing to work, then
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You’ve learned how to write, save, and run the program.
The language is working on your computer.
Your computer is working as expected.
So “Hello, World!” acts as a simple check that things are working
ok before you get involved in a complicated programming effort.
An HTML Example
<HTML>
<HEAD>
<TITLE>Hello, World!</TITLE>
</HEAD>
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<- Begins HTML ->
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<- Begins Header portion ->
<- Title ->
<- Ends Header portion ->
<- begin body ->
<-Displayed on web page ->
<- End body ->
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<- End HTML ->
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<BODY>
Hello, World!
</BODY>
</HTML>
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Introduction to JavaScript
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JavaScript
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Was developed to be compatible with web page design, so it runs
inside of web page documents.
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That means that JavaScript programs sit inside of HTML documents.
It allows computation to be performed within web pages, and uses the
web page for input and output.
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The <script language=“JavaScript”> and </script> tags define the
limits of the JavaScript program inside of the HTML document.
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JavaScript is general purpose (fully computational language), but it is
limited as to file access for security reasons.
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An interpreted language (interpreted by the browser). This makes it a
little slow when running, but makes it easy to quickly change your
program and see the result.
A JavaScript Example
<HTML>
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<HEAD>
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<TITLE>JavaScript Hello,
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World!</TITLE>
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</HEAD>
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<BODY>
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<SCRIPT LANGUAGE=“JavaScript”>
document.write(“Hello, World!”);
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</SCRIPT>
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</BODY>
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</HTML>
<- Begins HTML ->
<- Begins Header portion ->
<- Title ->
<- Ends G=Header portion ->
<- Begin Body ->
<- Begin Script ->
<-Displayed on web page ->
<- End Script ->
<- End body ->
<- End HTML ->
Getting Started with JavaScript
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JavaScript requires that you declare every variable you intend to
use. Declarations look like this for simple variables:
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JavaScript uses the following arithmetic operators on integers
and numbers:
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var x;
Var myvariable;
+ is addition
- is subtraction
* is multiplication
/ is division
JavaScript has many special purpose functions built in for your
convenience
Output of Results with JavaScript
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JavaScript is an Object-Oriented language, which means it treats
everything as if it were a physical object.
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There are specific built-in objects with specific built-in functions.
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The object that deals with input and output is the “document”
object. Outputting results with the document object looks like
this:
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document.write(“Hi.”);
document.write(17);
document.write(x);
document.write(“x”);
-> Displays the word “Hi.”
-> Displays the number 17
-> Displays the value of x.
-> displays the letter “x”.
The Tiny Von Neumann Architecture
ADDRESS
000
MEMORY
001
002
100
The Instruction Cycle:
FETCH: Fetch an instruction from the memory address pointed to by the PC (Program counter), place it in the instruction
register (IR) and increment the PC by one.
EXECUTE: The OP tells the computer what is the instruction that must be executed.
NOTE: The PC always points to the instruction that will be fetched. When the program is loaded in memory,
the PC points to the first instruction of the program.
Instruction Set Architecture:
LOAD <X>
Loads the contents of memory location “X” into AC (AC stand for Accumulator).
ADD <X>
The data value stored at address “X” is added to the AC and the result is stored back in the
AC.
STORE <X>
Store the contents of AC into memory location “X”.
SUB <X>
Subtracts the value located at address “X” from the AC and stored the result back in the AC.
IN <Device # >*
A value from the input device is transferred into the AC.
OUT <Device #> *
Print out the contents of the AC in the output device.
END
The machine stops execution of the program.
Instruction Set Architecture continued
JMP <X>
Causes an unconditional branch to address “X”.
PC  X
SKIPZ
If the contents of the Accumulator = 0 the next instruction is
skipped.
*
Device #
5
7
9
Device
Keyboard
Printer
Screen
For instance you can write: 003 IN <5> “23” where “23” is the
value you are typing in.
Instruction Set Architecture Codes:
01  LOAD
02  ADD
03  STORE
04  SUB
05  IN
06  OUT
07  END
08  JMP
09  SKIPZ
Instruction format assuming 6 digits, 2 are used for the op-code and 6 for
the address, for example LOAD <0004> will be represented as:
LOAD 0004
It can be written as “010004” using decimal numbers.