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CORK INSTITUTE OF TECHNOLOGY
INSTITIÚID TEICNEOLAÍOCHTA CHORCAÍ
Autumn Examinations 2009/
Module Title: Microprocessor Systems 1
Module Code: ELTR
School: Electrical and Electronic Engineering
Programme Title: Bachelor of Engineering in Electronic Engineering
Programme Code: CR_EELXE_7_Y
External Examiner(s): Dr A Donnellan
Dr P O’Sullivan
Internal Examiner(s): Mr J O’Sullivan
Instructions: Attempt any three questions. All questions carry equal marks.
Duration: Two hours
Sitting: Autumn 2010
Requirements for this examination: N/A
Note to Candidates: Please check the Programme Title and the Module Title to ensure that you have received the correct examination paper. If in doubt please contact an Invigilator.
You are expected to present your answers in a neat and tidy fashion Start each question on a new page Remember that there is plenty of time – two hours to do three questions
Q1. (a) Microcomputers are often used as embedded controllers – explain what is meant by this statement. Draw a diagram showing the main parts of a microcomputer. [5 marks]
(b) Two’s complement numbers are used to represent positive and negative values in a computer – explain how the computer can distinguish between positive and negative values using this number system. [1 mark]
(c) Determine the decimal equivalent of the 8-bit two’s complement value 101101002 – show all workings. [4 marks]
(d) Express the two’s complement binary value in (c) above as a 16-bit value written in hexadecimal. [4 marks]
(e) Why are separate compare and subtract instructions often found in computers when both perform the same mathematical operation of subtraction? [1 mark]
(f) Assuming the binary value in (c) above is held in D0.B, explain fully whether or not the computer will branch to LABEL following the program segment CMP.B #$B4,D BEQ LABEL [5 marks]
Q2. (a) What is the difference between low-level and high-level programming languages? [3 marks]
(b) State with reasons whether assembly language, which we use to write programs on the Flight-68K system, is a low-level or high-level programming language. [3 marks]
(c) Draw a flowchart to show how you would solve the following programming task: It is required to check the 16-bit value stored in location $400500 and if it is found to be negative, replace it with its positive equivalent. [6 marks]
(d) Write a program in assembly language with appropriate comments to carry out this task on a 68000-based computer, such as the Flight-68K. [8 marks]
Q3. (a) Draw a block diagram of the 68000 MPU and state the function of each block. [10 marks]
(b) Explain what is meant by the term fetch-execute cycle as it applies to the operation of a computer. [4 marks]
(c) The following line of code appears in a 68000 program listing: 00400400 044061A8 SUB.W #25000,D Show how this instruction would appear in memory and making reference to the block diagram in (a) above. Briefly describe the associated fetch-execute cycle. [6 marks]
