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Comp 454:Microprocessor Interface March 2009 Question Paper
Comp 454:Microprocessor Interface March 2009
Course:Bachelor Of Science In Computer Science
Institution: Kabarak University question papers
Exam Year:2009
KABARAK UNIVERSITY EXAMINATIONS
2008/2009 ACADEMIC YEAR
FOR THE DEGREE OF BACHELOR OF SCIENCE IN
COMPUTER SCIENCE
COURSE CODE: COMP 454
INSTRUCTIONS:
ATTEMPT QUESTION ONE AND ANY OTHER TWO QUESTIONS
QUESTION ONE CARRIES 30 MARKS AND THE REST 20 EACH
QUESTION ONE (30 MARKS)
(a) (i) A microprocessor is not a stand alone unit. Briefly explain. (1 mark)
(ii) Distinguish between peripherals and interface units. (2 marks)
(iii) Mentioned the five major differences that exists between the central computer
and a peripheral. (2.5 marks)
(b) (i) Name the five basic categories of I/O interfaces. (2.5 marks)
(ii) Mentioned the three modes of data transfer between the microprocessor and
the peripherals (1.5 marks)
(iii) Name the lines that constitutes an I/O bus (2 marks)
(c) (i) There are four types of commands that an interface may receive when being
addressed by the CPU. Name them. (4 marks)
(ii) Asynchronous communication interface is said to be ‘double buffered’.
Explain. (2 marks)
(iii) Direct memory access (DMA) interface is initialized by the CPU. The process
of initialization involves specifying four parameters. Name them. (4 marks)
(d) Distinguish between the following:
(i) Vectored and Non-vectored interrupts (2.5 marks)
(ii) Serial priority and parallel priority (2 marks)
(iii) Bit time and baud rate (2 marks)
(e) In data transfer under program control, if the input-output device is connected to
the microprocessor
(i) In memory-mapped
(ii) In Isolated mode
Show the instructions that may be used to transfer the contents of Ac to the I/O device
in each of above cases (3 marks)
QUESTION TWO (20 MARKS)
(a) Explain the interrupt initiated mode of data transfer between the
microprocessor and a peripheral device. (5 marks)
(b) Draw a block diagram showing the implementation of this mode of transfer.
(7 marks)
(c) On receipt of the interrupt signal, State the four operations that the processor
must do to implement the process. (8 marks)
QUESTION THREE
An interface has two hand shake lines. A source labeled data valid (DAV) and a
destination labeled data accepted (DAC). For a source initiated transfer,
(a) Draw a block diagram showing the pertinent connection between the CPU and the
Peripheral. (4 marks)
(b) Draw a timing diagram. (3 marks)
(c) (i) In some details explain the mode of transfer between the source and the
destination unit. (8 marks)
(ii) Derive a sequence of events flow chart. (5 marks)
QUESTION FOUR
A DMA unit receives characters of 8- bits from a peripheral device, packs four characters
in 32-bit word, and stores words of 32-bit in the memory.
(a) Design a block diagram that defines a set of registers for the DMA, CPU and the
memory unit. (5 marks)
(b) Draw a flow chart showing the sequence of events for the memory operations with
the DMA (12 marks)
(c) During the interrupt cycle, show the sequence of micro operations performed by the
CPU in a priority interrupt hard ware. (3 marks)
QUESTION FIVE
(a) Draw a block diagram of an asynchronous communication interface connected to
a microprocessor. (10 marks)
(b) Mention the parameters that must be specified during the process of initialization
of the interface by the CPU (4 marks)
(c) Explain the operation of the transmitter portion of the interface. (6 marks)
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