CPSC220: Introduction to Computer Architecture (Fall 2013)

Assignment #2.5

Due at the start of class on Thursday, 09/19/2013

Three more, all from class on Friday, September 13

To do

  1. Create a circuit that performs 1-bit incrementation of its argument. There are two inputs, A and cin, representing the input and a carry-in value. There are two outputs, S and cout, where S = A + cin (in one bit), and cout is the carry-out value of the sum.

  2. Create a 4-bit incrementation circuit. This circuit has four input wires, A0 ... A3, representing the four bits of input. The output should have five outputs, S0 ... S3 and cout, representing the four-bit value of A+1 and the carry-out value.

  3. Implement addition and subtraction in a single circuit, with the ability to choose the mode. There are 9 inputs, A0 ... A3, B0 ... B3, and D. The first 8 represent the 4-bit inputs for A and B, while D represents the "mode".

    There are four outputs, S0 ... S3. If the input D is 1, the circuit will output the 4-bit value A+B on S0 ... S3. If it is 0, then the output should be A-B.

    In all cases, the least significant bit should be at x0, the most significant at x3. Assume a 2's complement representation of negative numbers.

    You can and should reuse subcircuits as you need them.

Turn in:

Save these three problems in a file called hw2-5.circ

To hand in your files: