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This page is provided to help explain some
of the terms and that you may encounter as you explore the World Wide Web (WWW).
Additionally, other computer related, useful information will be added to this page as
requested. To request additional information on a specific topic, contact the webmaster.
Terms and Definitions
A bulletin board system lets you post messagesand
sometimes program and text filesfor other members to see. Many BBSes also give you
an email account and access to the Internet. There are tens of thousands of BBSes; most
are operated by special-interest groups, while others are maintained by schools, research
institutions and government agencies.
Electronic mail is a message that s passed between
people over a computer network. An email message looks a bit like a business memoit
has a header that lists the sender s name, the date and time sent, and the subject.
Pronounced fak, this term is short for
"frequently asked questions. The first time you go to a BBS or a Web site, it s a
good idea to read the FAQ file if there is one before posting new questions they may
already have been asked and answered.
Think of this as a Web site s title pageit
typically describes the individual or institution operating the site. In most cases, home
pages include hypertext links to other areas of the site and often to related information
at other Web sites.
This term refers to text that s
cross-referencedlinkedto related information on the Web. Links operate like
the "See also" section in an encyclopedia article. Clicking on links, which are
displayed in a different color or typeface, takes you to the related material
Internet Relay Chat, like the telephone party lines of
yesteryear, allows people anywhere on the Net to join in real-time discussions by typing
messages on their keyboards and reading replies on their screens. IRC is split into
channels, like those on a CB radio; each has a different conversation.
Even the Net has loose "rules"or at
least conventions of politeness recognized by regular users. For instance, it violates
Netiquette to type a message all in capital lettersit s like SHOUTINGor to
promote a commercial enterprise in a general-interest newsgroup or BBS.
Usenet, a bulletin-board system on the Internet, houses
more than 20,000 single-topic message boards called news-groups. They can be
unmoderatedmeaning anyone can post a messageor moderatedsubmissions are
directed to a moderator who edits or filters them before posting the results.
Pronounced either "earl" like a man s name or U-R-L,
a Uniform Resource Locator is an addresssuch as www.whitehouse.govthat
identifies a site on the Internet. The suffix .com denotes a commercial site, .edu a site
based at an educational institution, gay a site run by a governmental organization
and so on.
What is meant by a 3GL with regard to
GL's are generational languages!
A 1st GL is one which directly manipulates the computer hardware
through the hardwiring of boards and such. This was how the first programs were done
on computers years and years ago. If you ever see old footage of those big computers and
all those wires plugged in here and there, that s the program. This also includes code
written in machine language (which no one does). An EXE tends to be in machine-language,
but this is because a program written in a later generation language is compiled to the
native tongue, so to speak.
A 2nd CL is one which is structured and has a syntax (like any
language, all programming languages have a syntax that defines how to use it, just like
English or French does). But it is low-level code, where the programmer controls many of
the program s variables and registers (hardware storage areas on a CPU). This code is
considered extremely efficient, because you tell the program exactly how and when to do
things. Asembly language falls under this category. It is very hard to read and debug. It
also is usually tied to a specific processor. Since how the under-pinnings of a computer
differ between types and Operating Systems, a program in Assembler written on a PC would
not work on any other platform (Mac, Unix box, etc.)
A 3rd GL is a structured language, but there is an abstraction
layer between the program and the hardware, and the compiler (which compiles source code
into applications) handles all concerns and worries regarding the processor, registers,
etc. This is called abstraction (or an abstraction layer) . Most of your major languages
(like C, Pascal, COBOL even) fall into this category. The main thing is that since the
program has no regard to the hardware, the code itself can be used on multiple platforms
(assuming there is a compiler written for that platform which can compile the code) . So,
a standard C program written for a PC could work on a Mac with just a recompile.
Unfortunately, 3rd GLs are pretty simplistic in the provided functionality (to make the
language standardized, for example, there is no specification for any type of windowing
features), so all compiler manufactures add in there own extensions to the language to
make programming easier on whatever platform. But this cuts down on the
crossplatformness of the language (unless the compiler maker creates a compiler with
those extensions on other platforms as well)
While a 3rd GL abstracts you from hardware, it does nothing to
abstract the program from how data is stored and used in your program. In all 3GLs, the
programmer knows the internal structure of data and how it is stored/manipulated by the
program (even if the language does the manipulation, the programmer still knows the
A 4th GL is one where there is even a greater abstraction layer
between the program and the hardware. Visual Basic falls under this category (it also is a
little fuzzy on the specific reasons on why it is fourth rather than 3rd, except it sounds
better to Microsoft, I m sure). In a 4GL, data is abstracted from the program as well. The
programmer defines a variable to hold a string (say the Course Title), but does not know
how the string is stored, and cannot directly manipulate the string (you can manipulate
the string, but only through the interface defined by the language). This moves the burden
of handling the data away from the programmer and onto the compiler, making the programmer
s job easier and the code clearer. It also allows the compiler to tweak or change the way
data is stored internally, without it affecting the program itself.