jueves, 12 de abril de 2012

Decodificador de 3 a 8 con GAL22V10 (Laboratorio)


LABORATORIO  (Decoder 3 _8)
Diseñe un sistema combinacional de tres entradas llamadas C, B y A con ocho salidas llamadas S7, S6, S5, S4, S3, S2,S1, S0, de manera que cuando la entrada sea igual a C = 0,B = 0 y A = 0, sólo la salida S0 sea igual a 1. Si la entrada es igual a C = 0, B = 0 y A = 1, sólo la salida S1 sea igual a 1 y así sucesivamente, hasta que la entrada sea C= 1, B = 1 y A = 1; entonces sólo la salida S7 será igual a 1.

Debe implementarse con GAL22V10 de acuerdo al esquema mostrado:




Tablas de Verdad con LOGICAID


LogicAid simplifica funciones Booleanas tanto en suma de productos como en Producto de Sumas, a partir de una tabla de Verdad, con o sin condiciones de indiferencias, sin necesidad de utilizar Mapas de Karnaugh.

Transcribimos del original en inglés del Manual escrito por el Autor del Software el procedimiento a utilizar:

User’s Guide and Reference Manual for
LogicAidTM
Second Edition for WindowsTM
CAD Software for Logic Design
Charles H. Roth, Jr
University of Texas at Austin 

Entering Truth Tables:
Given a truth table as input, LogicAid will find simplified equations for the functions defined by the truth table. The steps required to enter a truth table are as follows:
1. Select Truth Table from the Input menu (or type CTRL+T).
2. When the Input Truth Table Format dialog box appears, type in the number of input variables if it is different from the default value of 4.
3. If your table has more than one output function, hit Tab and then enter the number of functions.
4. The default input variable names are X1, X2, X3, …; the default function names are Z1, Z2, Z3, …. If you wish to change any of these, select Enter Names.
5. The default format for the input combinations in the truth table is Straight Binary. Order. If you prefer to use a different input format, select Decimal, Binary (0, 1, –), Hexadecimal, or Octal. The default for the output combinations is Binary (0, 1, –), but Decimal, Hexadecimal, or Octal may also be selected.
After the table has been entered, output values for the remaining rows will default to all 0’s unless 1-terms or X-terms is selected.
6. When you have finished selecting formats, click OK.
7. If you have selected Enter Names, the Input Variable Names dialog box will appear next. Change any names that you want to be different from the default values and then click OK. (You may advance from box to box by using the Tab key.)
8. An input window titled “Truth_Table” appears next. The header at the top of the window lists the input variable names and output function names. Enter the truth table below this header. If you have selected the default format for inputcombinations (straight binary order), the binary input combinations will automatically be generated for you. For example, for three input variables, 000 will appear on the screen.
Type in the corresponding output values and hit Enter. Then type in the output values corresponding to row 001, etc. When you have entered the output values for the last row in your table, hit F12 instead of Enter.
NOTE: Once you hit F12, the program switches to manual mode and any further input combinations must be typed in manually. The following example shows a truth table with three inputs and three outputs (binary format): 
Input Variables: X1 X2 X3
Output Functions: Z1 Z2 Z3
___________________________
000 100
001 010
010 00—
011 001
100 011
101 —1—
9. If you do not use the default format (straight binary order), then for each row of the truth table, type the input combination followed by a space or Tab, and then type the output values. The following example shows the input for the same truth table using decimal format for the input combinations:
Input Variables: X1 X2 X3
Output Functions: Z1 Z2 Z3
___________________________
0 100
1 010
2 00-
3 001
4 011
5 -1-
10. Next, you may select Check Syntax from the Input menu (or type ALT+I Y). If you have made any syntax errors, a dialog box will appear which explains the type of error. Click OK, and the cursor in the input window will indicate the approximate location of the error. Edit the truth table to correct the error(s). The header cannot be changed in the edit window.
If there are no errors in your truth table, you receive no message.
Select Change Parameters from the Input menu to change the input or output variable names.
11. Simplifying Logic Equations, to derive simplified expressions for the functions defined by the truth table.