QI. (Covers Block 1)

(a) Please refer to Figure 4 of Unit of Block 1 on page 11. Assuming the same machine to
be used for execution of the following three consecutive instructions

LOAD C Loads the content of Memory location into the Accumulator Register.
ADD B Adds the content of memory location in the Accumulator Register
STORE A; Stores the content of Accumulator register AC in memory location A

The following are the details about the instructions, data and registers.
Each word of memory is of 32 bits in length. Each instruction is also 32 bits long
Main Memory has 256 words
nsecutive instructions as shown above starts from memory location (IF)
A is at location (FD) and contains a value (1000) B is at location (FE) and
contains a value (FF3B) and C is at location (FF) and contains a value (2A2F
The AC, IR and MBR registers are of size 32 bits, whereas PC and MAR registers are
of size 8 bits. The initial content of PC register is (IF)

Registers
Draw the diagrams
showing addresses and content of memory locations and
Show how the content of memory locations and registers will change with the execution
of the three instructions. Show all the addresses and values in hexadecimal notations You
must also perform the necessary arithmetic using signed 2’s complement notation and
show the results indicating overflow. if any. Also explain the process of execution of the
suouanisu
(4 Marks)

(b) Perform the following conversion of numbers
i) Decimal 3412454512 to binary and hexadecimal
ii) Hexadecimal (FEDCBA9) into Octal
iii) String “In file name % means blank. into UTF8
iv) Octal 7766432 into Decimal

(2 Marks)

(c) Assuming that inverse is represented as simplify the following Boolean functions
F ((A + B)+(A+B)

(d) Simplify the following function using K-map: F(A., B, C, D) (0, 2681014
Draw the circuit using NAND gates.

(2 Marks)

Consider the Adder-Subtractor circuit as shown in Figure 3.15 page 76 of Block 1.
Explain how this circuit will perform subtraction, if the value of A is 1111 and B is 1100.
You must list all the bit values including Cin and Cout and overflow condition. (1 Mark)

Explain the functioning of a 2x Multiplexer. You must draw its truth table and explain
its logic diagram with the help of an example input.
(2 Marks)

(g) Assume that a data value 111 was received as 1011. Explain how use of Hamming’s
Error Correcting code will send this data value from source and correct error at the
destination
(2 Marks)

(h) Explain functioning of S-R flip flop with the help of logic diagram, characteristic table
and excitation table.
(2 Marks)

(i) Explain the functioning of Asynchronous and Synchronous counter. Explain how are
they different from each other
(2 Marks)

Differentiate between fixed point numbers and floating point numbers? Explain the
representation for Zero in IEEE 754 single precision standard. Represent (-32.25) 0 and
00001250 in IEEE 754 single precision format.
(2 Marks)

Q2. (Covers Block 2)

(a) Reference Figure 2(b) on page 8 in Unit 1 of Block 2. Draw the Internal organisation of a
64 8 RAM. Also answer the following:
(i) How many data input and data output lines does this RAM needs? Explain your

answer
(i) How many address lines are needed for this RAM? Give reason in support of your
(2 Marks)
answer.

(b) A computer has 16 MB RAM and has a word size of 32 bits. It has cache memory having
16 blocks having a block size of 64 bits. Show how the main memory address (17F0AB)
will be mapped to cache address, if
() Direct cache mapping is used
(ii) Associative cache mapping is used
(iii) Two way set associative cache mapping is used.
You must clearly identify tag, index, main memory block address and offset etc. in your
answer.
(3 Marks)

(c) Explain the process of Interrupt handling and Return from interrupt with the help of a
diagram. You must answer this question in your own words.
(2 Marks)

(d) Differentiate between the working of DMA and I/O processor, Explain the DMA
configurations and I/O channel structures

fe Assume that a disk has 2000 tracks with each track having 256 sectors and each sector is
of size 2M. A file having the name openUni.txt is of size 32 M. Assume that disk has 16
free – continuous clusters of 4 sectors ench at different locations on the disk. How can this
file be allotted space on the disk? Also show the content of FAT after the space allocation
to this file, You may make suitable assumptions. You may assume the cluster size as 4
sectors, if needed
(4 Marks)

(f) Explain the following giving their uses and advantages/disadvantages.

(Word limit for answer of each part is 50 words ONLY)
6) SCSI and IDE in the context of Interfaces
Scanner and its resolution
(iii) Scan codes in the context of keyboard
Access time on disks
(A) Virtual Memory
(vi) RAID level 0.3 and 5

(6 Marks)

(Covers Block 3)

(a) A computer has a single core processor having 16 General purpose registers and 4
additional special purpose registers. The machine has 1MB RAM. The size of each
register and memory word is 32 bits each. An instruction of the machine is of fixed
length and is equal one memory words. Each instruction of the machine can have two
operands one memory operand and second register operand (register operand can be in
General
purpose
immediate operand only). Memory operand either uses direct addressing
or is an
however, register operand can use either register direct or register
indirect addressing. (Please note that if register operand uses indirect addressing, then
stated register contains the address of the operand in the memory.) An instruction of a
machine consists of operation code bits, two addressing mode bit, one register operand
and one memory operand. The addressing mode bits specifies addressing mode as:

Addressing mode bit Register Operand Memory Operand
00
Indirect
Direct
01
Direct
Direct

10

Indirect Immediate Operand
Direct Immediate Operand

The special purpose registers are Program Counter (PC), Memory Address Register
(MAR), Data Register (DR) and Flag registers (FR). The First register of the General
purpose registers can be used as Accumulator Register. The size of Integer operands on
the machine is 32 bits and it may be assumed to be of equal to size of accumulator
register. In order to execute instructions the machine has an additional Instruction
Register (IR) of size 32 bits as each instruction is of this size. Perform the following tasks
for the machine

()
Design suitable instruction formats for the machine. Specify the size of different
fields that are needed in the instruction format. Also indicate how many different

operations can be coded for this machine. Give reasons in support of your answer.

(3 Marks)
(1)
Put some valid values in registers and memory locations and demonstrate
examples of different addressing modes of this machine

memory operands is brought to DR register, indirect operand is brought to
Accumulator register: and result of operation is stored in the Accumulator
register: write and explain the sequence of micro-operations
fetch and execute cycles of an instruction which
operands having addressing mode bits as 00. Please note that one of the onerand
is Indirect Register Operand and the second is a direct
and state suitable assumptions, if any

that are required for
performs subtraction of two

memory operand. Make
(6 Marks)

(b) Assume that you have a machine as shown in section 3.2.2 of Block 3 having the micro-
operations as given in Figure 10 on page 62 of Block 3. Consider that RI and R2 both are
8 bit registers and contains 11000011 and 11100101 respectively. What will be the values
of select inputs, carry-in input and result of operation (including
following micro-operations are performed? (For each
the initial value of R1 and R2 as given above)
Add RI and R2 with carry
Decrement RI
(iii) Shift right R1 twice
AND RI and R2

carry out bit) if the
micro-operation you may assume

(2 Marks)

(iv)

(c) What is the role of Control Signal in execution of an Instruction? Block 3, page number
68-70, explains the timing sequence for execution of ISZ instruction. Explain execution
of an ADDITION instruction with the help of micro-operations and timing sequence.

(3 Marks)

(d) What is the role of micro-programmed control Unit? How a micro-program is executed?
Explain with the help of a diagram.

(2 Marks)

(e) List and explain the characteristics of RISC machines. A RISC machine has 256 registers
out of which 64 registers are reserved for the Global variables and 64 for Instruction
related tasks. This machine has been designed to have 12 registers for storing three input
parameters, three output parameters and six local variables for a function call. Explain
with the help of a diagram, how the overlapped register window can be implemented in
this machine for function/procedure calls. You must explain how the parameters will be
passed when a function calls another function. How
a machine can support?

many levels of procedural calls, such
(3 Marks)

Q4. (Covers Block 4)

(a) Write a program using 8086 assembly Language (with proper comments) that accepts an
input of ten characters from the keyboard and store them in the memory. It then converts
all the lower case alphabets of this stored
assumptions, if any.

string to uppercase alphabets. Make suitable

(7 Marks)

(b) Write a program using 8086 assembly Language (with proper comments) that find the
sum and average of 10 byte numbers stored in two different arrays of size 5 each.

(c) Explain the following in the context of 8086 Microprocessor

(7 Marks)
(6 Marks)

Use of Segment Registers
Use of Interrupts in Input/output

(iii)

.com and exe programs