EECE 320 Midterm, Fall 2007

American University of Beirut Faculty of Engineering and Architecture Electrical and Computer engineering Department EECE 320 Digital Design Midterm Thursday November 29th, 2007 Name ________________________________________ ID _________________________ Dr. Lama Hamandi Duration: 1h :15 min Question 1 12 Question 2 20 Question 3 10 Question 4 10 Question 5 13 Question 6 10 Question 7 25 Total Grade 100 Instructions:  Check to insure that you have a complete copy of the examination. There are 7 Questions, and a total of 8 pages. There should be no blank pages in your set.  This examination is closed book and closed notes.  The use of Electronic calculators or other equipment is not allowed during the examination.  No use of scratch paper is allowed. You should work your Questions directly on the Question statement sheet in the appropriate space only. You may use the backside of the exam sheets as appropriate.  Include all steps and calculations as appropriate for maximum credit. Be clear, brief, and specific in your answers. Good Luck! Question 1: (12 points) ---------------------------------------- proposed time 10 minutes Convert: 1. (1101010111)2 to hexadecimal: __________________ 2. (ADE.B)16 to Decimal: _____________ 3. (101101.011) 2 to decimal: _____________ 4. (757.25) 10 to octal: _____________ EECE 320 Digital Design – Midterm Fall 2007-2008 29-Nov-2007 2 Question 2: (20 points) ---------------------------------------- proposed time 10 minutes A combinational network has four inputs RSTU and four outputs VWYZ. RSTU represent a BCD number. VW represent the quotient and YZ represent the remainder of dividing RSTU by 3. Assume invalid inputs will never occur. Draw the circuit using only NAND gates. EECE 320 Digital Design – Midterm Fall 2007-2008 29-Nov-2007 3 Question 3: (10 points) ---------------------------------------- proposed time 10 minutes Using the rules of Boolean algebra, factor Z = ABC + DE + ACF + AD' + AB'E' and simplify it to the form (X+X)(X+X)(X+X+X+X) where each X represents a literal EECE 320 Digital Design – Midterm Fall 2007-2008 29-Nov-2007 4 Question 4: (10 points) ---------------------------------------- proposed time 5 minutes Use the following PAL to design the combinational circuit with 4 inputs A, B, C and D and the following outputs: W = A’B’ + A’C, X = C’D’ + CD, Y = A’B’ + A’C + AD’ + ABC’ Use the following convention to show the programmed PAL: EECE 320 Digital Design – Midterm Fall 2007-2008 29-Nov-2007 5 Question 5: (13 points) ---------------------------------------- proposed time 10 minutes Implement this function using two 74138 decoders connected as a 4-to-16 decoder and one additional gate. F(A,B,C,D) = A'B'C' + ABD + A'C + A'CD' + AC'D + AB'C' EECE 320 Digital Design – Midterm Fall 2007-2008 29-Nov-2007 6 Question 6: (10 points) ---------------------------------------- proposed time 5 minutes Write F as a minimal sum of product. EECE 320 Digital Design – Midterm Fall 2007-2008 29-Nov-2007 7 Question 7: (25 points) ---------------------------------------- proposed time 20 minutes Assume the following decoder and three-state buffer entities have been declared. 1- Write the behavioral description of the entity Dec138. 2- Create an entity that defines the interface for the following circuit 3- Write its structural architecture definition using the previously defined entities. EECE 320 Digital Design – Midterm Fall 2007-2008 29-Nov-2007 8 ENTITY Dec138 IS Port ( G1, G2A_L, G2B_L : IN STD_LOGIC ; A : IN STD_LOGIC_VECTOR( 2 DOWNTO 0) ; Y : OUT STD_LOGIC_VECTOR(0 TO 7) ) ; END Dec138 ; ENTITY Threestate IS Port ( E_N : IN STD_LOGIC ; I : IN STD_LOGIC ; O : OUT STD_LOGIC ) ; END Threestate ; I0 I1 I2 I3 I4 I5 I6 I7 A2 A1 A0 A B C