----- Original Message -----
SFrom: "Jerry Van Baren" <[EMAIL PROTECTED]>
To: "Rockbox" <[EMAIL PROTECTED]>
Sent: Thursday, September 28, 2006 8:34 AM
Subject: Re: Rockboy
Ed Toro wrote:
It's hard to port rockboy. I was trying to port it to my toaster. I think
it
runs vxworks.
No, toasters need to run unix(R).
gvb (old joke follows ;-)
Hardware vs. Software
Once upon a time, in an absolute monarchy 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 electrical engineer, answered first. "It is a toaster."
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. Wait 'til
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. Would-be diners
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 80586 with 16MB of memory, a 1.2GB
hard disk, and a SuperVGA 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 the kingdom lived
happily ever after.