Answer all the problems
1)
(a) Convert the following numbers as asked:
(i) Decimal 999 to Hexadecimal
(ii) Octal 555 to Hexadecimal
(iii) Hexadecimal AAAA to Decimal
(iv) Hexadecimal AAAA to Octal
(b) Suppose that computer represents negative integers in signed 2’s complement notation having the size of 8 bits. You might also suppose that all registers used for integer arithmetic are of 8 bits. Carry out the following operations using this computer (numbers indicated in the operations are decimal numbers). Indicate overflow condition, if any.
(i) Add -38 and -90
(ii) Subtract 90 from 38
(iii) Add 63 and 65
(iv) Subtract -90 from -65
(c) A four bit data 0001 is to be sent across communication channel. What must be the parity bits for SEC code, if this data is to be sent correctly across to destination? Indicate where these SEC code bits would be placed in the data + code bit combination which is to be sent. Suppose that data bits which were received were 1 S 0 S 0 S 1 (SEC bits remained unchanged in between wherever they were, that is the value of S might the related SEC bit or Null ). Correct this code using SEC bits generated at the receiver and the SEC bits received from the sources. Demonstrate all the steps of this process.
(d) A logical function calculator compares two numbers for the function A >= B. The comparator output 1 of the comparison is TRUE else FALSE. In case if both A and B are equal, the comparator outputs a second bit as 1 (0 otherwise). Partial truth table for comparator is given in Figure :
Number A Number B Output
Bit 1 Bit 0 Bit 1 Bit 0 Same Zero
0 0 0 0 1 1
0 0 0 1 0 0
... ... ... ... … …
0 1 0 0 1 0
0 1 0 1 1 1
... ... ... ... … …
1 0 1 1 0 0
1 1 1 1 1 1
Complete the truth table and design and draw the combinational circuit using AND-OR-NOT gates for the description given.
(e) Why do you require a flip-flop? Describe characteristics table of J K flip flop. How is it different than that of S R flip flop? Describe synchronous counter in the context of change of states of the flip flop.
(f) What is associative memory? Describe with the help of the diagram. What is a Cache memory? What are its different organisations? Describe Associative cache memory organization with the help of a diagram showing mapping from main memory to cache memory. You should show proper addresses for both the memories in the diagram. Though, for simplicity, you might take size of the main memory as 32 byte and cache as 4 byte.
(g) You have been asked to design the configuration of a database server (please do not give the names of manufacturer), specifically the RAID configuration for your server. Which of type of RAID machine will you select? Give justification in support of your answer. Also describe the process of interrupt handling when more than one interrupts can occur simultaneously.
(h) Describe the functions and purposes of Direct Memory Access (DMA) and Input/output processor in Computer. Determine how in Pentium processor I/O devices are connected to the system bus.
2)
(a) Is it possible to have Instruction set with no operands at all? Justify your answer. Suppose that the machine is to be designed for performing simple arithmetic operations (including unary and binary), what must be optimum number of operand in an instruction set for such machine? Give justification in support of your answer. How does the number of operand addresses in the Instruction Set affect the size of the program on computer?
(b) A machine is to be designed such that it stores arbitrary length arrays in memory. This machine also supports subroutine calls. Suggest four best addressing modes for the machine. Give reasons for your choice.
(c) Consider instruction ISNZ Op where Op is a register operand which is the address of the instruction of the executing program. Instruction checks if the value of the preceding instruction execution is NOT ZERO (the result might be in the AC register), if so then it branches to address specified by the Op. prepare sequence of micro-operations which would be needed to execute this instruction. You might use various micro-operation cycles and the essential registers.
(d) Suppose that 8-bit Register R has the data 01101110. Perform the following operations on the register R:
(i) Selective Set the lower 4 bits to 1100
(ii) Extract the lower 4 bits
(iii) Clear the register using a logical operation
(iv) Insert a value 1111 in the lower 4 bits of the register.
(e) Represent the following floating point numbers using IEEE 754 floating point single precision format.
i. 32.0125
ii. -0.125
(f) Describe the working of the control unit of a computer with the help of a Block diagram. Describe significance of micro-instruction in computer. Describe differences between horizontal and vertical microinstructions.
3)
(a) prepare the advantages of having segments in 8086 micro-processor? Describe the use of stack segment register and process of computations of physical address of the top of the stack in 8086 microprocessor.
(b) Describe the REPE, CMPS, AAA, and XLAT instructions of 8086 processor with the help of one ex each.
(c) Describe any one direct, one register indirect, one based indirect and one indexed indirect addressing modes of 8086 microprocessor with the help of the ex of each.
(d) Describe process of Input/output using Interrupt 21h in 8086 microprocessor with the help of exs.
(e) prepare program in 8086 assembly language which finds total of an array of maximum 10 integer elements. You might suppose that array is stored in memory and last value in the array is -2000. The find outd result is stored in location named sum.
(f) prepare program in 8086 assembly language which passes two input parameters to the subroutine through stack. Subroutine return value 1 if the value of first parameter is greater than the second, otherwise returns 0. Make appropriate assumptions, if any.