CS3410 Homework 1: FAQ Instructor: Kavita Bala Due: Wednesday, September 17th, 2008, 11:59pm
September 16, 4:05PM:  When debugging your ALU you might want to make use of the "probe" element in Logisim.  It is in the base folder.  A probe, when connected to any wire, displays the value of that wire.  It looks very similar to the input and output components, however it has one advantage: the probe element can be configured to display numbers in decimal, hexadecimal and binary.  The decimal display is especially convenient for testing. September 14, 9:25PM:  An automated tool will be used to grade your HW.  In order for it to work correctly you must ensure that the Logisim sub-circuit containing your solution is named precisely "ALU" and the inputs/outputs named "A", "B", "Op", "Sa", "C",  and "O". September 13, 2:45PM:  There has been a couple of questions about circuit reuse versus clarity.  Our solution to HW1 uses one adder circuit and one left shifting circuit.  All of the other required functionality -- subtraction, comparison, right shifting, etc. -- can be achieved by transforming the inputs and outputs of these units.  Your goal should be the same.  You will be penalized if your final ALU circuit uses more than one adder or left shifter.  Of course always strive to make your implementation clear, but do not duplicate components in an effort to do so. September 12, 1:30PM:  To implement the overflow required in the ALU specification will require adding additional outputs to the adder.  Feel free to add anything reasonable to adder to achieve the correct overflow output to the full ALU.
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