Is a PC a computer? Well, of course. That's easy, it's a Personal Computer.
What about an iPad? Yes. The fact that it does not have a real
keyboard doesn't matter,
although it is a severe limitation in some circumstances.
How about a Nintendo Gameboy? No, not really. It violates one
of the fundamental
requirements of a computer. No, it's not the missing keyboard that's
the problem.
How about a robot? Is it a computer? Some robots qualify, but others don't.
| Definition
- COMPUTER - A computer must have 4 basic features : Input, Output, Processing and Storage. It is NOT necessarily true that it must be built from digital electronics circuit components, although most computers are built that way. |
Thinking about a "normal" PC, we see that it has a keyboard and mouse for
input
and a screen for output. What about processing? That is all
the computations done by
the CPU (Central Processing Unit)
- also called the microprocessor.
What about storage? That is provided by the hard-disk, when you
save or copy files.
The iPad isn't much different, except that it uses a touch-screen
for input AND output,
and storage is done in Flash Memory
instead of a spinning disk. It has a different kind
of CPU, but it is a CPU nonetheless.
In a Nintendo Gameboy, which of the 4 basic features is missing?
It takes input from a game controller
(buttons). Output appears on an LCD screen.
It must be processing something, because it makes decisions about whether
you
win or lose, as well as when the next enemy should appear. The main
limitation is
a lack of storage space. It does store top scores in a small amount
of flash memory,
but that is severely limited. That is not the type of storage we
mean. Nonetheless,
we could still study it as a very simple computer.
- What about robots?
Describe a robot that actually has the 4
required features, and identify
the devices that provide these features.
- Describe some other examples of
computers.
Make them as different as possible. In each case,
identify each of the 4 features.
- Is a music player (iPod, MP3 player) a computer?
The traditional (50 years old) definition of a computer is IPOS (Input, Processing, Output, Storage). In our modern connected world, we want to add Communication as a another feature. It's not really a required feature, because many computers function in stand-alone mode most of the time. But even the wise old men must admit that communication is a significant issue, so we will add C as an important, but not required, feature. The IT people did this a few years back, changing IT to ICT. The author has decided to emphasize the optional nature of communication by using a small "c" - so you will see IPOcS in this document.
As distributed computing
becomes more and more important (Google certainly thinks so),
that small "c" my supplant the capital S, so that we have IPOCs - but that
is probably still
a generation away. Actually, the term computer
is probably simpler and will be used frequently.
Now we return to the original question - why study computer SYSTEMS,
rather than just studying computers? The answer to this question is
rather complex, but we can start with a simple observation: since
computers are often connected to other computers, and are influenced by
those other machines, we need to worry about what's happening in the
entire system, not just what is happening in single devices. That's
an oversimplification of the issue, but it will suffice for now.
We've got a definition for a computer - IPOcS. Can we define what a computer SYSTEM is?
Computer SYSTEMS contain a lot more than just the computers and digital devices that are part of the SYSTEM. Computer SYSTEMS contain HARDWARE and SOFTWARE and, perhaps most important, MEATWARE - the computer scientist's deprecating term for users (people). But we must also add ORGANIZATION as a significant issue.
Computer SYSTEMS are large and complex. If we get carried away we might
describe an AIR TRAFFIC CONTROL SYSTEM in terms that include the
planes, radar dishes, computer monitors, technicians, pilots, passengers,
taxis, web-sites, international laws .... OOPS! We shouldn't get
carried away and include EVERYTHING that is connected. But we must accept
the possibility that other components are equally important to individual
computers.
| Description
-
Computer SYSTEM A computer SYSTEM is a collection of components, including: Software, Hardware, Organization and People (SHOP), where computers and digital devices play a significant role in the functioning of the system. |
The descriptions above don't actually tell us very much, but they do
provide a schema for studying
things. When we are talking about a computer system, we want to remember
that the users and the overall organization are equally important to the
hardware and software that is purchased.
The best way to study anything is to start with two words - FOR
EXAMPLE. Here are some examples of computer devices and
computer systems to discuss. A sample story about a computer system
is often called a scenario -
that means it's a story describing general issues. Your job is to fill in
as many details and analyze as many issues as possible.