Binary questions!

Need Help plss.... in binary question

Design the following digital circuits using AND, OR and NOT gates:

a) A binary addtition- substraction circuit that adds or subtracts two 4 bit binary numbers. The circuit has a selection bit that controls whether addition or substraction is to be performed.

b) Draw a combinational circuit that convverts a single hexadecimal number to an equivalent BCD (binary coded decimal)number.

c) A 2 bit counter that counts till 2 that is the counting states are: 00,01,10,00,01,10,00.. .. .. etc

Thanks
Madz

Comments

  • You'd probably have better luck on a hardware or assembly page, though I wouldn't be too surprised if one of these basic'ers knew a bit more than me and has experience in those areas (I sure as heck don't).

    : Need Help plss.... in binary question
    :
    : Design the following digital circuits using AND, OR and NOT gates:
    :
    : a) A binary addtition- substraction circuit that adds or subtracts two 4 bit binary numbers. The circuit has a selection bit that controls whether addition or substraction is to be performed.
    :
    : b) Draw a combinational circuit that convverts a single hexadecimal number to an equivalent BCD (binary coded decimal)number.
    :
    : c) A 2 bit counter that counts till 2 that is the counting states are: 00,01,10,00,01,10,00.. .. .. etc
    :
    : Thanks
    : Madz
    :

  • : Need Help plss.... in binary question
    :
    : Design the following digital circuits using AND, OR and NOT gates:
    :
    : a) A binary addtition- substraction circuit that adds or subtracts two 4 bit binary numbers. The circuit has a selection bit that controls whether addition or substraction is to be performed.
    :
    : b) Draw a combinational circuit that convverts a single hexadecimal number to an equivalent BCD (binary coded decimal)number.
    :
    : c) A 2 bit counter that counts till 2 that is the counting states are: 00,01,10,00,01,10,00.. .. .. etc
    :
    : Thanks

    a)
    This will show you how to build a 4-bit adder:
    http://people.ucsc.edu/~gyao/project.ppt

    This will show you how to convert it to add or subtract:
    http://www.courses.psu.edu/cse/cse275_pxw23/labs/4-bit_adder-subtractor.pdf

    b)
    ?? - I'm thinkin! Hmmmm? How 'bout...
    pass the four inputs through 2input and gates. The second gate inputs are all tied together to form a "4-bit switch".
    Now, decode the A,B,C,D, and E states of the 4-bit input and present them as the second 4-bit BCD digit. (actually only need 3 bits as the BCD digit value will never be above five.) A three input and gate on the msd BCD can be used to turn off the lsd BCD switch to make that digit equal to zero.

    .... that's kind of a ramble, but it might give you some ideas!

    c)
    will this work??.....
    use and / or / inverters to build j-k flip flops...
    use two flipflops as a 2-bit counter
    connect the inputs of a 2-input and gate to the ff outputs.
    connect the output of the and gate to the reset inputs of both ff's

    Enjoy!

    rg
  • [b][red]This message was edited by Folker Fritz at 2003-10-13 15:19:34[/red][/b][hr]
    : Need Help plss.... in binary question
    :
    : Design the following digital circuits using AND, OR and NOT gates:
    :
    : a) A binary addtition- substraction circuit that adds or subtracts
    : two 4 bit binary numbers. The circuit has a selection bit that
    : controls whether addition or substraction is to be performed.


    'i whould try to do this with hex values like:
    A& = &H03 + &H04
    PRINT A$

    'or you can try to extract each bit and then add it:
    B$ = CHR$(122)
    B = ASC(B$)
    FOR temp = 8 TO 1 STEP -1
    IF B >= (2 ^ temp) / 2 THEN WRIT$ = WRIT$ + "1" ELSE WRIT$ = WRIT$ + "0"
    IF B >= (2 ^ temp) / 2 THEN B = B - (2 ^ temp) / 2
    NEXT
    'WRIT$ contains now every bit: 01111010
    'you can now use the bit you want, here the first 4 for example:
    c = c + VAL(MID$(WRIT$, 1, 1)) * 1
    c = c + VAL(MID$(WRIT$, 2, 1)) * 2
    c = c + VAL(MID$(WRIT$, 3, 1)) * 4
    c = c + VAL(MID$(WRIT$, 4, 1)) * 8
    PRINT "Value of first 4 bits:", c


    : b) Draw a combinational circuit that convverts a single hexadecimal number to an equivalent BCD (binary coded decimal)number.


    'HexToValue:
    VAL( "&H" + h )
    'BinToValue:
    VAL( "&B" + h )
    'HexToBin:
    BIN$( VAL( "&H" + h ) )
    'BinToHex:
    HEX$( VAL( "&B" + h ) )


    : c) A 2 bit counter that counts till 2 that is the counting states are: 00,01,10,00,01,10,00.. .. .. etc


    'look at my answer for question a, you can do it the same way.


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