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Unformatted text preview: Objective(s): In this lab, the student’s objective is: • To build an ALU, arithmetic and logic unit, using the subcircuits build in Simulation Lab 1 and Lab 2. Expected Outcome(s): The expected outcome is: • To ___________ an elementary arithmetic and logic unit. o Build. o Test. o Debug. o Implement into a subcircuit. • Describe the ALU operations of which it is capable of. • Describe the input control line values that correspond to each ALU operation of the ALU. • Write a topdown description of a complex logic circuit. • Calculate the approximate propagation delay time of a combinationallogic unit [1]. o INC A0 A1 A2 A3 CRY Y0 Y1 Y2 Y3 INC_4 A3 A2 A1 A0 /~Pass NOT/~NEG Y3 Y2 Y1 Y0 CRY Results: Task 3.1 Build the NOT/NEG circuit Task Statement: The task was to build a NOT/~NEG circuit using the subcircuit INC_4. Figure 1 – A Schematic NOT/~NEG circuit. The task was to design a NOT/~NEG circuit using the INC_4 built in a previous lab. To do this, the inputs are XORed with a value /~PASS which determines whether the value just passes through. The INC value is AND’d with the /~PASS value to determine that when the pass is 1, if the function is to be 1’s complement or 2’s complement. Cin B0 B1 B2 B3 A0 A1 A2 A3 CRY Y0 Y1 Y2 Y3 FA_4 A0 A1 A2 A3 A0 A1 A2 A3 B0 B1 B2 B3 B0 B1 B2 B3 B0 B1 B2 B3 A0 A1 A2 A3 AN0 AN1 AN2 AN3 AN0 AN1 AN2 AN3 AD0 AD1 AD2 AD3 AD0 AD1 AD2 AD3 MUX_4 A/~B B1 B0 B2 B3 A0 A1 A2 A3 Y0 Y1 Y2 Y3 A0 A1 A2 A3 MUX_4 A/~B B1 B0 B2 B3 A0 A1 A2 A3 Y0 Y1 Y2 Y3 /~PASS A3 A2 A1 A0 B3 B2 B1 B0 Cin AND/~ADD Y3 Y2 Y1 Y0 Cout Figure 2 – Testing the NOT/~NEG Circuit (Pass, Pass, NEG, NOT) In testing the circuit, when the /~Pass is 0, the output is whatever the input is showing that the function is simply a passthrough function. The value of the NOT/~NEG does not matter if the /~PASS is 0. When the value of /~PASS is 1, there are two possible functions of the NOT/~NEG depending on the NOT/~NEG value. When the value is 0, the function is two’s complement. When the input is 5, 0101, the output is B which is 1011. When the value is 1, the function is one’s complement. When the input is 5, 0101, the output is A which is 1010. 0101, the output is A which is 1010....
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This note was uploaded on 02/22/2011 for the course EEE 120 taught by Professor Tylavsky during the Spring '10 term at ASU.
 Spring '10
 TYLAVSKY

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