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 it is, he asked.
One advisor, an Engineer, answered first. It is a toaster, he said.
The King then 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 sixteen shades of darkness: from snow white to coal black. The program would use that darkness level as the index to a sixteen-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 timer delay it would turn off the heat and pop up the toast. Come back next week, and Ill show you a working prototype.
The second advisor, a Computer Scientist, immediately realised the danger of such short sighted thinking. Toasters dont just turn bread into toast, he began, they are also used to warm frozen waffles. What you see before you is really a breakfast 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 scramble eggs. A toaster that only makes toast will soon become obsolete. If we dont look to the future, we will have to completely redesign it in a few years.
With this in mind, he continued, 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; 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 can see how 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 the message depend, of course, on the kind of object, so it has a different meaning to a piece of toast than to a scrambled egg.
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 dont want their eggs to get cold while the bacon is frying, so concurrent processing is needed, too.
We must not forget the user interface. The lever that lowers the food lacks versatility, and the darkness knob is confusing. Users wont 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 v8.3 appears on the screen. (UNIX 8.3 should be out by the time this product goes to market.) Using a mouse they can pull down a menu and select which 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 80386 with 8Mb of RAM, a 30Mb hard disc 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.
The Computer Scientist looked scornfully at the Engineer. Imagine the difficulty we would have had if wed foolishly allowed a hardware-first design strategy to lock us into a four bit microcontroller!
Needless to say, the King had the Computer Scientist beheaded and they all lived happily ever after.
A blond gets a new cell phone from her husband.
The next day she goes to Wal-mart and her phone rings, so she answers it. It was her husband. He says, Hows the new cell phone? She replied, Great…but how did you know I was at Wal-mart?
You can sleep with them all you want and not have to worry about
getting them pregnant.
You dont need a touchy-feely manual (Women are from Mars, Men are
From Venus etc) to understand each other.
When youve screwed up and made a fool of yourself, a teddy bear
will never say I told you so.
You can have as many favorites as you want and they wont get
jealous.
Theyre always ready for a cuddle anytime, anywhere.
They dont mind it a bit if you stay out at all hours with the boys.
No matter what guy thing youre in to, they always enjoy what
you enjoy.
Top Ten Changes at NASA to Accommodate 76-Year-Old John Glenns Return to Space Aboard the Shuttle Discovery:
- All important devices now operated by the Clapper.
- Shuttles thermostat set at 80 degrees.
- Shuffle board installed in cargo bay.
- Early Bird specials from Morrisons Cafeteria included on menu.
- One monitor specifically designated for Matlock.
- Little bowls of candy scattered randomly about the ship.
- Top speed of shuttle set at 25 miles per hour.
- Installed a new bifocal windshield.
- Space pants now go up to armpits.
- Left-blinker left on for entire mission.
Pair of edible Depends found on bedroom floor.
Lately, at night, they put their teeth in the same glass.
Grandpa grabs his crotch and complains loudly of denture-burn.
Granny found cuffed to her walker.
Not only do you hear the bed squeaking, but also joints.
Grandma regularly looks at Grandpas crotch and claps twice.
Your Grandma is Anna Nicole Smith.
Youve just seen the photos in the Beaver Hunt section of the May issue of Hustler.
Grandmother starts baking Viagra-chip cookies.
And the Number One Sign Your Grandparents are still sexually active …
Kraft-matic adjustable bed set for doggy style.
Q: If called to testify in a trial how long will it before before Clinton commits perjury?
A: When hes sworn in.
1.Su cachorro aprenderá a orinar en el lugar indicado sólo cuando su alfombrado esté completamente arruinado.
2.Las mascotas de la gente común tienen pulgas, las mascotas de la gente con dinero tienen alergia.
3.Para su mascota, absolutamente todo es masticable.
4.Un piso limpio estimula los esfÃnteres.
5.La probabilidad de que su mascota rompa un objeto es directamente proporcional al costo de dicho objeto.
6.Todo los que su animalito sabe hacer sólo podra relatarlo, porque jamás lo hará en presencia de extraños.
7.Cuanto más molestias y dinero invierta en conseguir un juguete para su mascota, menos lo usará.
8.Su mascota sólo necesitará un veterinario de urgencia cuando usted no tenga dinero.
9.Un perro con las patas secas y limpias jamás saluda a un invitado bien vestido.
El hombre según la edad:
De los 10 a los 15 es mono: Vive pelando la banana.
De los 16 a los 20 es jirafa: Se come las florecillas.
De los 21 a los 30 es buitre: Se come todo lo que se le atraviese.
De los 31 a los 40 es águila: Escoge todo lo que se va a comer.
De los 41 a los 50 es papagayo: Habla más de lo que come.
De los 51 a los 60 es lobo: Persigue a Caperucita pero se come a la abuela.
De los 61 a los 70 es cigarra: Canta, canta y no come nada.
De los 71 a los 80 es cóndor: Con-dolor aquÃ; con-dolor allá…
De los 81 en adelante es paloma: sólo caga.
En una iglesia de pueblo, el cura le pide a un pintor local que le pinte un enorme cuadro de La Última Cena, en una de las paredes de la parroquia. El artista pueblerino comienza a crear su obra, soplándose, de vez en cuando, unos tragos de alcohol. Cinco horas más tarde termina y le manda llamar al sacerdote para que le diera su punto de vista.
El clérigo empieza a contar a los apóstoles y advierte que son trece. Entonces, le reclama al pintor que deberÃan ser doce apóstoles y que querÃa que el decimotercero fuera borrado o que hiciera algo con ese apóstol que sobraba. A la hora regresa el sacerdote y, al mirar el cuadro, advierte que encima de uno de los discÃpulos habÃa un letrero con el siguiente texto:
Yo no soy apóstol ni nada, yo nomás como y me voy a la chingada.
There is a lady who dies and goes up to heven. She sees all these clockes everywhere and asks an angle why they are there. The Angle says, Well every time you lie your clock spins around once. Like hers George Washingtons, his clock never moved, same with Jesus over here. So the lady asks where Bill Clintons is. The Angle replies. Well jesus is using it as a celling fan in his office.