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Unformatted text preview: ee457_MT_fl07.fm 11/2/07 EE457 Midterm Exam for future practice - Fall 2007 Page - 1 / 13 C Copyright 2007 Gandhi Puvvada Fall 2007 EE457 Instructor: Gandhi Puvvada Midterm Exam (20%) Date: 11/2/2007, Friday Time: 4:00 - 6:25PM SGM123/124 Name: Total points: 224.5 Perfect score: 200 / 224.5 1 ( 10 + 10 + 10 = 30 points) 20 min. Simple data path and control (difficult question, do it at the end): Shown below is a small part of a larger 28-state design. The single bit registers A, B are changed only in the three states shown below. Part of the datapath associated with the single bit registers A, B is also shown on the next page. The three 2-to-1 muxes upstream of each flip-flop help you to route the four different values to the input of the FF. Four different values or three different values? Well, do not forget to recirculating the current value back to itself in the rest of the states! A. Please complete datapath connections to the input of the muxes on the next page B. Please complete the needed logic (output function logic) to drive the 6 select lines Assume one-hot state assignment for the states C. Please complete the waveforms for A and B for Ain = 1 and Bin = 0 D. Please complete the waveforms for A and B for Ain = 0 and Bin = 1 10 pts 10 pts if A = 1, then flip A (i.e. A <= A ); B <= A; QS12 A <= B; B <= A ; QS28 A <= Ain, B <= Bin; QS1 START S T A R T RESET ACK ACK 1 Ain = 1 Bin = 0 Ain = 0 Bin = 1 ee457_MT_fl07.fm 11/2/07 EE457 Midterm Exam for future practice - Fall 2007 Page - 2 / 13 C Copyright 2007 Gandhi Puvvada 2 ( 22 points) 20 min. Performance (difficult question, do it at the end): There are four categories of instructions, A, B, C, and D, taking 3, 4, 5, and 6 clocks per instruction (CPI) respectively. Your colleague proposed to change resources in the datapath to improve performance of instructions in the A category by 1 clock even though this causes increase in the number of clocks taken by instructions in the D category by 3 clocks (without changing clock frequency). So, the new CPI of A,B,C, and D will be 2, 4, 5, and 9. He argues that A is more frequently used compared to D, so overall this should be beneficial. Consider each of the following two questions separately and individually and arrive at its answer if adequate data is available. If data is inadequate, state what is missing to arrive at the needed answer. 2.1 If the frequency of occurrence of instructions of category D is 2% in the dynamic execution trace of a benchmark, what should be the minimum frequency of occurrence of instructions of category A you need before you can consider the proposed change to the datapath? __________________________________________________________________________________ __________________________________________________________________________________ __________________________________________________________________________________ __________________________________________________________________________________ __________________________________________________________________________________...
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This note was uploaded on 04/03/2011 for the course EE 457 taught by Professor Puvvada during the Fall '08 term at USC.
- Fall '08