DISTANCE EDUCATION
M.C.A. DEGREE EXAMINATION, MAY 2017.
First Semester
DIGITAL COMPUTER ORGANIZATION
(2010 Academic year onwards)
Time Three hours Maximum 100 marks
SECTION A — × 8 40 marks)
Answer any FIVE questions.
1. Perform the indicated base conversions:
548 to base 5
3124 to base 7.
2. Write the Boolean expression for a four-input NAND
gate.
3. Construct the operation XOR from the basic Boolean
operations AND, OR, and NOT.
4. Design an 1-to-8 demultiplexer.
5. How can you form the negation of an integer in two's
complement representation?
6. Assume numbers are represented in 8-bit two's
complement representation. Show the calculation of the
following: 13 6 13.
7. What is the difference between DRAM and SRAM in
terms of characteristics such as speed, size, and cost?
8. What is the difference between memory-mapped I/O and
isolated
Sub. Code
101
DE-681
2
Ws 11
SECTION B — × 15 60 marks)
Answer any FOUR questions.
9. What is the difference between cannonical form and
stardard form? Which form is preferable when
implementing a Boolean function with gates? Which form
is obtained when reading a function from a truth table?
10. Obtain the simplified expressions in product of sums:
13, 15)
11. Implement full adder circuit with multiplexers.
12. Implement a full subtractor with two half subtractors and
an OR gate.
13. Design a BCD counter with JK flip-flops.
14. Suggest reasons why RAMs traditionally have been
organized as only 1 bit per chip whereas ROMs are
usually organized with multiple bits per chip.
Consider a dynamic RAM that must be given a refresh
cycle 64 times per ms. Each refresh operation requires
150 ns; a memory cycle requires 250 ns. Whet percentage
of the memory's total operating time must be given to
refreshes?
15. When a device interrupt occurs, how does the
processor determine which device issued the
interrupt?
When a DMA module takes control of a bus, and
while it retains control of the bus, what does the
processor do?