Wednesday, July 30, 2014

Procedures in Pro-Bot

Let’s start this lesson by taking a look at your typical school day. What are some of the functions that you perform on a given school day? Here are a few: you wake up, make your bed, brush your teeth, take a bath, get dressed, eat breakfast, travel to school, study, play, eat lunch, study again, travel home, play, sports/activities, watch TV, read a book, do homework, eat dinner, brush your teeth, sleep... If you look closely at each of these functions, you notice that each one of these involves multiple steps.

For example, brushing your teeth more or less involves the following steps: (1) pick up toothbrush (2) pick up toothpaste (3) squeeze the toothpaste onto the brush (4) actual brushing of the teeth (5) open the tap for water (6) fill up your glass (7) close tap (8) rinse your mouth (9) put away the toothbrush and toothpaste.

We bunched up all these steps and gave it a unique name: “brush teeth”. When your dad or mom wants you brush your teeth, do they say all these 9 steps one by one, or do they just say “brush teeth”? Why? Because you understand what “brush teeth” means. You have been taught in your younger days what that means and how to do all those 9 steps. All those steps are in your memory. So when you hear it, you know all the steps to do.

Now let us take a look at a computer… like your Pro-Bot. Don’t you think if a computer is first told how to draw a 6 cm side square, then each time you want to draw a 6 cm side square, you should be able to say a unique name like “square” or draw square”, or something like that, instead of telling it each time “Fd 6, Rt, Fd 6, Rt, Fd 6, Rt, Fd 6, Rt”? Guess what? The computer can do that! And that is what we call “Procedure”.

A procedure is a set of computer program instructions that performs a specific task.
In your daily life example, “brush teeth” is a procedure. It is a small group of instructions that performs a specific function. Any time your parent wants you to perform this function (which involves those 9 steps), he or she would just call it by the name “brush teeth”, rather than specify every step involved in it. This way, they get to reuse the “procedure” they taught you and made you memorize. Similarly, in a computer program, you write those steps once into the computer’s memory and give it a unique name. Then you can use it multiple times in your program.

Maybe, the dentist has advised you and your parents to include flossing into your routine. Flossing is also a procedure just like “brush teeth”. It involves some of these steps: (1) take the box of floss, (2) cut off about 10 inches of the flossing thread (3) coil it around your fingers (4) insert it between 2 of your teeth and pull (5) repeat this for all the gaps between your teeth (6) uncoil the string from your fingers (7) throw it into the garbage. Your parents work with you to teach you these steps until you have learned it. Then while brushing your teeth, he or she may remind you to “floss”. They don’t have to tell you all those 7 steps every time anymore. So here you can see that the “floss” procedure is called from within the “brush teeth” procedure.

Now let’s go back to the computer. Let’s say you want it to make a beeping sound after you draw the square. What would you do? You could write a procedure to make that beeping sound. Then call that “beep” procedure from within your “square” procedure after all those steps to draw the square. In this way, you just easily modified your first procedure to do something different.

Thus, you can call other procedures from within a procedure.

Back to our “brush teeth” example. You may decide to floss before you do other steps in your “brush teeth” procedure, or after you have done those steps. Similarly you may decide to make the Pro-Bot “beep” before it starts drawing the square instead of after drawing the square. Can you see how easy that would be? You just have to call the “beep” procedure first instead of last within your “square” procedure.

You can think of “school day” as a Program, and functions like “wake up”, “make bed”, “brush teeth”, etc., as Procedures inside the program. Now, try writing two different programs using the procedures for the daily functions: one program for a school day and the other program for a holiday. You can easily see that you would not call every one of the procedures for either program. There might be some procedures that are common to both programs and there might be some that are exclusive to each. Such as, you don’t “travel to school” on a holiday, but you “brush teeth” every day. You might also call them in different orders for the two programs. For example, you may watch TV at different times during a holiday, than on a school day.

Procedures thus help us to customize our programs easily.

We already mentioned that procedures and programs can call other procedures from within. They can be called multiple times as well. You can write a procedure for drinking water. You might call this procedure multiple times throughout the day, while performing other functions. This means that you can call “drink water” from within your “eat lunch” procedure or from within your “play” procedure or from within your “do homework” procedure, etc.

How to create and edit a procedure for Pro-Bot
Pro-Bot lets you create and store up to 32 procedures in its memory. In the case of Pro-Bot, these procedures are named Proc 1, Proc 2, …, …, Proc 32.
Pro-Bot’s Menu button provides two options to access procedures:
·      New Proc
·      Edt Proc

Let’s discuss each of these options.
1.   New Proc:
Press the Menu button & then scroll down to “New Proc”. Choose this option when you want to create a new procedure. It will show you a list of 32 procedures on the screen. Choose any procedure name from this list (Proc 1 to Proc 32). Let’s say that you choose Proc 3. Your Pro-Bot screen will now show Proc 3. Type in the instructions for the specific function that you want Proc 3 to perform. Next, press Menu. This will take you back to the Main program. You can now call Proc 3 from your Main program anytime you want to use it. You do this by pressing the “Proc” button and then the number key 3.

2.   Edt Proc:
Press the Menu button & then scroll down to “Edt Proc”. Choose this option when you want to edit a procedure that you created earlier. It will show you the list of 32 procedures on the screen. Choose the procedure that you want to edit from this list. Let’s say that you choose Proc 3. Your Pro-Bot screen will now show the instructions that you put in earlier for Proc 3 (or an empty program if you put in no instructions earlier). Make the changes that you want for this procedure. Next, press Menu to go back to the Main program. You can now call Proc 3 from your Main program and it will provide you with the updated functionality.

For example; you can write a procedure to draw a square of side 6 cm. Let’s say we name this procedure “Proc 1”. Proc 1’s code will be “Rpt 4 [ Fd 6   Rt ]”. You can store this procedure in memory and anytime you need to draw a 6 cm square, you just call Proc 1 from your Main program.

In addition to the 32 procedures that you can create and edit, Pro-Bot also provides 5 other procedures with pre-defined names related to the touch, light & sound sensors. You can edit these using the Edt Proc option from Menu. These procedures are:
·      33 FRONT (runs when the front touch sensor is triggered)
·      34 REAR (runs when the rear touch sensor is triggered)
·      35 DARK (runs when the light sensor goes from light to dark)
·      36 LIGHT (runs when the light sensor goes from dark to light)
·      37 SOUND (runs when the sound sensor is triggered)

There are also 3 built-in, pre-defined procedures that you cannot edit, but can call from Main. These are:
·      38 HEXGN: draws a hexagon
·      39 DIAMND: draws a diamond
·      40 FLOWER: draws eight diamonds using Proc39

Note: You can call other procedures from within any other procedure. Just take care not to run procedures that call each other, in which case you would get into an endless loop.

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