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Sending and Receiving Data

 

Now let's say you have data in one calculator that you have computed and you want this to be in the second calculator for further computation. You transfer data from one calculator to another using "Send" and "Receive".

Let's say there are two calculators in your MarkCalc window, and you want to calculate 4+5 in the left calculator and send the result to the right calculator. Put the cursor in an empty command box of the left calculator, and press the calculator button labeled "Send", then press (or type) 4+5.

Next, go to the right calculator, put the cursor in an empty command box, and press the calculator button labeled "Receive".

You are ready to transmit the result--but you need to indicate where the "Send" command is supposed to send its result and where the "Receive" command is supposed to get its value. Move the mouse-point just to the right of the row containing the "Send" command, press the mouse-button, and move the mouse away. Notice that an arrow comes out of the calculator and follows the mouse-point around. If you let up on the mouse-button, the arrow disappears. Again move the mouse-point to the right of the "Send" row and press; this time, move the mouse-point just to the left of the "Receive" row, and let up on the mouse-button. Depending on your accuracy, the arrow should stick, connecting the left calculator to the right calculator. You can get rid of the arrow by putting the mouse-point on the arrowhead, pushing down the mouse-button, then moving the mouse-point away and letting up on the button.

If there is an arrow from the "Send" command to the "Receive" command, then when the "Send" command is executed, the value gets transmitted across the arrow. Note that the arrow gets thicker to indicate there is a value being transmitted across it. When the "Receive" command in the right calculator is executed, the transmitted value appears in the display of the right calculator. Typically, you would also give a name to that row (type the name into the "Name" box). That way, later commands in the right calculator could refer to the received value.

You can change arrows around as desired, removing them and making new ones. Your arrows can start on the left side of a calculator and end on the right side of another calculator, or vice versa. You can create arrows between commands that are not "Send" or "Receive" too, but such arrows serve no purpose. You can have several arrows coming out of one "Send" command row and going to different "Receive" command rows on different calculators; thus one Send can transmit the same value to different places. In fact, the way to effectively eavesdrop on the communication between two calculators is to add a new arrow from the Send command row of one calculator to a calculator of your own. You can also have multiple arrows pointing to the same Receive command row; this allows the calculator to receive values from different calculators.

It's sometimes tricky to get the arrows to work right; be sure you are pushing or letting up the mouse-button when the mouse-point is right alongside the appropriate row of the calculator. Also, if the row to which an arrow is attached is not visible within a calculator, you cannot grab the end of the arrow. To do so you must first scroll the rows (as described in Subsection 3.9) until the row in question is visible.

Be aware that typing the letters "Receive" or "Send" on the keyboard will not create a Receive or Send command; you must use the calculator buttons.


next up previous
Next: The Workspace Up: Using Multiple Calculators Previous: Using Multiple Calculators

Lisa Eckstein
Tue Sep 17 22:19:41 EDT 1996