final_exam - CMPT 250 : FINAL EXAMINATION Time: 3 Hours 6...

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CMPT 250 : FINAL EXAMINATION Time: 3 Hours 100 MARKS FALL 1998 6 Questions CLOSED BOOK 3 Pages 1. (8 marks) The CPU designed in the textbook required a register file to permit retrieval from two registers as well as the storage of data in a register, all simultaneously. a. Draw a black-box diagram for a 4 × 4 register file with all inputs and outputs labelled. Bus notation may be used for data inputs and outputs. b. For your black-box diagram provide a function select table that describes the effect of all possible assignments of values to the control inputs. c. Draw the logic diagram for the 4 × 4 register file using 4-bit registers, "standard" MSI components and gates if necessary. d. Explain why a standard RAM cannot be used to implement a register file. 2. (20 marks) A proposed instruction set includes instructions which employ the following address modes: direct, indirect, indexed, and relative. a. For each address mode, explain how the operand is obtained. b. Draw an ASM chart for the fetch cycle of a simple processor (no interrupts) which determines the effective address of the operand and places it in the MAR before proceeding to the execute cycle. Assume that the memory fetch cycle may take longer than one CPU clock cycle. c. Assuming the processor uses a PC, MAR, and MDR, draw a logic diagram of that part of the processor required to retrieve operands as specified by your fetch cycle. Use any additional registers or combinational components as required, and show all data flow paths and select logic. DO NOT provide details of the controller, but show all inputs and outputs implied by your fetch cycle ASM. 3. (12 marks) A 1-bit logic unit is specified by the following function select table: f2 f1 f0 | FUNCTION ---------|-------------------------------- 0 0 0 | Out <- 0 0 0 1 | Out <- In1 and In2 0 1 0 | Out <- In1 and In2’
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This note was uploaded on 01/16/2010 for the course CS 251 taught by Professor Various during the Spring '97 term at Simon Fraser.

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final_exam - CMPT 250 : FINAL EXAMINATION Time: 3 Hours 6...

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