CS vs. EE
- Attendees
- meter@bmerhbfc
- Colin Kemp 7K76 BNR
- Author
- Colin Kemp 7K76 BNR
- Summary
For your information:
---forwarded-message---->
May 07 10:21:00 1996
To: Holly (H.A.) Armstrong (BNR) Dept 7K76 SKY
Seyma (S.) Atik (BNR) Dept 7K76 SKY
James (J.L.) Beuerman (BNR) Dept 7K76 SKY
Brett (R.B.) Buckingham (BNR) Dept 7K76 SKY
Wee-Lin (W.L.) Chew (BNR) Dept 7K76-M SKY
Daniel (D.G.) Doliska (BNR) Dept 7K76 SKY
Colin (C.W.) Kemp (BNR) Dept 7K76 SKY
John (J.A.) Posavad (BNR) Dept 7K76 SKY
Rajeev (R.) Rajagopal (BNR) Dept 7K76 SKY
Cameron (C.W.) Turner (BNR) Dept 7K76 SKY
Xinxin (X.) Wang (BNR) Dept 7K76 SKY
From: Peter (P.J.) Frellick (BNR) Dept 7K76 SKY
Subject: CS vs. EE
Just a follow-up to Seyma's joke
---forwarded-message---->
Once upon a time, in a kingdom not far from here, a king summoned two
of
his advisors for a test. He showed them both a shiny metal box with
two
slots in the top, a control knob, and a lever. "What do you think
this
is?"
One advisor, an engineer, answered first. "It is a toaster," he said.
The king asked, "How would you design an embedded computer for it?"
The engineer replied, "Using a four-bit microcontroller, I would write
a
simple program that reads the darkness knob and quantizes its position
to
one of 16 shades of darkness, from snow white to coal black. The
program
would use that darkness level as the index to a 16-element table of
initial timer values. Then it would turn on the heating elements and
start the timer with the initial value selected from the table. At
the
end of the time delay, it would turn off the heat and pop up the
toast.
Come back next week, and I'll show you a working prototype."
The second advisor, a computer scientist, immediately recognized the
danger of such short-sighted thinking. He said, "Toasters don't just
turn
bread into toast, they are also used to warm frozen waffles. What you
see before you is really a breakfast food cooker. As the subjects of
your
kingdom become more sophisticated, they will demand more capabilities.
They will need a breakfast food cooker that can also cook sausage, fry
bacon, and make scrambled eggs. A toaster that only makes toast will
soon be
obsolete. If we don't look to the future, we will have to completely
redesign the toaster in just a few years."
"With this in mind, we can formulate a more intelligent solution to
the
problem. First, create a class of breakfast foods. Specialize this
class
into subclasses: grains, pork, and poultry. The specialization
process
should be repeated with grains divided into toast, muffins, pancakes,
and
waffles; pork divided into sausage, links, and bacon; and poultry
divided
into scrambled eggs, hard-boiled eggs, poached eggs, fried eggs, and
various omelet classes."
"The ham and cheese omelet class is worth special attention because it
must inherit characteristics from the pork, dairy, and poultry
classes.
Thus, we see that the problem cannot be properly solved without
multiple
inheritance. At run time, the program must create the proper object
and
send a message to the object that says, 'Cook yourself.' The
semantics
of this message depend, of course, on the kind of object, so they have
a
different meaning to a piece of toast than to scrambled eggs."
"Reviewing the process so far, we see that the analysis phase has
revealed
that the primary requirement is to cook any kind of breakfast food. In
the design phase, we have discovered some derived requirements.
Specifically, we need an object-oriented language with multiple
inheritance. Of course, users don't want the eggs to get cold while
the
bacon is frying, so concurrent processing is required, too."
"We must not forget the user interface. The lever that lowers the
food
lacks versatility, and the darkness knob is confusing. Users won't
buy
the product unless it has a user-friendly, graphical interface. When
the
breakfast cooker is plugged in, users should see a cowboy boot on the
screen.
Users click on it, and the message 'Booting UNIX v. 8.3' appears on
the
screen.
(UNIX 8.3 should be out by the time the product gets to the market.)
Users can pull down a menu and click on the foods they want to cook."
"Having made the wise decision of specifying the software first in the
design phase, all that remains is to pick an adequate hardware
platform
for the implementation phase. An Intel 80486 with 16MB of memory, a
60MB
hard disk, and a VGA monitor should be sufficient. If you select a
multitasking, object oriented language that supports multiple
inheritance
and has a built-in GUI, writing the program will be a snap. (Imagine
the
difficulty we would have had if we had foolishly allowed a
hardware-first
design strategy to lock us into a four-bit microcontroller!)."
The king wisely had the computer scientist beheaded, and they all
lived happily ever after.
The end