Computer Systems

What is a computer SYSTEM?  Why can't we just study computers and digital devices?

What is a Computer?

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

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.

Discussion Questions

- 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?

Wired World

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.

Systems

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.

Scenarios

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.

Smart Phones for School Faculty
A school is considering purchasing a Smart Phone (possibly iPhone) for each faculty member. They tried to convince the faculty members to purchase their own phones, and many did, but about half of them refused.  Anyway, one of the administrators decided that these Smart Phones should meet a consistent specification so that the school could be certain that specific APPS and Web-sites would function reliably.  Hence it is advantageous for the school to buy the phones and distribute them to the entire faculty.
- What are the important issues to consider?
- What are some sensible uses for these devices?
- What are some not-so-sensible uses that should be avoided?
- Would the problem change if Smart Phones are also purchased for students?
- Analyze both the SYSTEM issues and the DEVICE issues.
- Suggest a PROCESS for discussing issues and making the final decision.
- Imagine that you are hired by the school as a computer systems consultant.
  What questions would you ask?  What advice would you give?

Future PCs Scenario

Future PCs
A consortium of computer hardware and software manufacturers has been formed to consider and plan and hopefully influence developments over the next 5 years. They noticed recently that tablet sales are growing, notebook sales grew over the past 5 years and have now leveled off, and desktop PC sales are dropping steadily. Now the manufacturers must either change their production quotas or accept decreasing profits.  That isn't so bad, but the rather unpredictable prospect of further changes in the future has caused them to become proactive and to try to influence future trends. They have some initial "BIG  ISSUES" questions, but are expecting to develop more:
- What is the future of storage?  Will cloud storage replace hard-disk storage?
   What about SSDs (solid-state-drives)?  Flash memory?
- As portability becomes more and more desirable, battery life is an ever more important
   issue.  This has led to low-power processors, including ARM processors. 
   What are the likely and/or desirable future trends in CPU architecture?
- If we abandon desktop PC manufacturing and only produce and market notebook
   computers, are there any business or personal application areas that will suffer?
- Will the trend from wired networks to wireless networks continue?  If so, how can
   we avoid losses in speed and productivity?
- If the consortium does decide to emphasize or encourage specific trends,
   how can they implement this?
- What mistakes have previous consortiums made, like the Windows Phone?
   How did these mistakes happen and how can they be avoided?