Quiz4Soln - CDA3101 Quiz 4 Fall 2006 Last Name _ First Name...

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CDA3101 Quiz 4 Last Name ____________________ Fall 2006 First Name ____________________ 1. Consider the following single-cycle datapath and control. Instruction ALUOp1 ALUOp0 Function Code ALU control bits lw 0 0 X X X X X X 0010 sw 0 0 X X X X X X 0010 beq 0 1 X X X X X X 0110 add 1 0 1 0 0 0 0 0 0010 sub 1 0 1 0 0 0 1 0 0110 and 1 0 1 0 0 1 0 0 0000 or 1 0 1 0 0 1 0 1 0001 a) Why do we need the multiplexor that is tied to the “Write Register” input of the Register File? Don’t just say “to choose between this and that”, be specific about why any choice is necessary and give an example instruction that demonstrates each choice for the multiplexor. This mux is necessary to accommodate the R and I type instructions. The R type instruction always puts its destination register in bits 15-11, while the I type instruction (if it has a destination register) will always be in bits 20-16. So a choice must be made, based on the instruction type, as to which 5 bits of the instruction actually specify the destination register number. (Of course, RegWrite must be true
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This note was uploaded on 12/02/2009 for the course CDA 3101 taught by Professor Small during the Spring '08 term at University of Florida.

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Quiz4Soln - CDA3101 Quiz 4 Fall 2006 Last Name _ First Name...

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