random year question answer 08-04-2022

2010

What are 16-bit registers available in 8085 Microprocessor ?

-two 16-bit registers: stack pointer and the program counter.

What are the elements of machine instruction?

-All Operation code, Source operand reference, Result operand reference, and Next instruction reference are typical elements of machine instructions.

What is the difference between primary and secondary storage devices ?

Sr.No.	Primary memory	Secondary memory
1.	Primary memory is temporary.	Secondary memory is permanent.
2.	Primary memory is directly accessible by Processor/CPU.	Secondary memory is not directly accessible by the CPU.
3.	Nature of Parts of Primary memory varies, RAM- volatile in nature. ROM- Non-volatile.	It’s always Non-volatile in nature.
4.	Primary memory devices are more expensive than secondary storage devices.	Secondary memory devices are less expensive when compared to primary memory devices.
5.	The memory devices used for primary memory are semiconductor memories.	The secondary memory devices are magnetic and optical memories.
6.	Primary memory is also known as Main memory or Internal memory.	Secondary memory is also known as External memory or Auxiliary memory.
7.	Examples: RAM, ROM, Cache memory, PROM, EPROM, Registers, etc.	Examples: Hard Disk, Floppy Disk, Magnetic Tapes, etc.

What is stack ?

- A stack is a storage device that stores information in such a manner that the item stored last is the first item retrieved. The operation of a stack can be compared to a stack of trays. The last tray placed on top of the stack can be taken off.

What are the differences between RISC and CISC processors ?

CISC	RISC
A large number of instructions are present in the architecture.	Very few instructions are present. The number of instructions is generally less than 100.
Some instructions with long execution times. These include instructions that copy an entire block from one part of memory to another and others that copy multiple registers to and from memory.	No instruction with a long execution time due to a very simple instruction set. Some early RISC machines did not even have an integer multiply instruction, requiring compilers to implement multiplication as a sequence of additions.
Variable-length encodings of the instructions.  Example: IA32 instruction size can range from 1 to 15 bytes.	Fixed-length encodings of the instructions are used.  Example: In IA32, generally all instructions are encoded as 4 bytes.
Multiple formats are supported for specifying operands. A memory operand specifier can have many different combinations of displacement, base, and index register.	Simple addressing formats are supported. Only base and displacement addressing is allowed.
CISC supports array.	RISC does not support an array.
Arithmetic and logical operations can be applied to both memory and register operands.	Arithmetic and logical operations only use register operands. Memory referencing is only allowed by loading and storing instructions, i.e. reading from memory into a register and writing from a register to memory respectively.
Implementation programs are hidden from machine-level programs. The ISA provides a clean abstraction between programs and how they get executed.	Implementation programs exposed to machine-level programs. Few RISC machines do not allow specific instruction sequences.
Condition codes are used.	No condition codes are used.
The stack is being used for procedure arguments and returns addresses.	Registers are being used for procedure arguments and return addresses. Memory references can be avoided by some procedures.

2011

What is OP code ?

- Each assembly language statement is split into an opcode and an operand. The opcode is the instruction that is executed by the CPU and the operand is the data or memory location used to execute that instruction. ex. ADD (addition), SUB (subtraction), STA (store), LDA (load) etc.

What is instruction code ?

- A group of bits instructing the computer to perform a specific operation is known as instruction code.

#another answer

Instruction Set: Group of instructions given to execute the program and they direct the computer by manipulating the data. Instructions are in the form – Opcode (operational code) and Operand. Where, the opcode is the instruction applied to load and store data, etc. The operand is a memory register where instruction is applied.

What is Assembler ?

- An assembler is a type of computer program that interprets software programs written in assembly language into machine language, code and instructions that can be executed by a computer.

What is biased exponent ?

- In floating-point arithmetic, a biased exponent is the result of adding some constant (called the bias) to the exponent chosen to make the range of the exponent nonnegative. Biased exponents are particularly useful when encoding and decoding the floating-point representations of subnormal numbers.

What is binary adder ?

- A Binary Adder is a digital circuit that implements the arithmetic sum of two binary numbers supported with any length is known as a binary adder. The binary adder generally categorized in three parts. 1. Half adder (used to add two bits), 2. Full adder (used to add three bits) and 3. Parallel adder (used to add more than two bits).

Explain the major characteristics of an RISC processor.

• RISC(Reduced instruction set computing)architecture has a set of instructions, so high-level language compilers can produce more efficient code
• It allows freedom of using the space on microprocessors because of its simplicity.
• Many RISC processors use the registers for passing arguments and holding the local variables.
• RISC functions use only a few parameters, and the RISC processors cannot use the call instructions, and therefore, use a fixed-length instruction that is easy to pipeline.
• The speed of the operation can be maximized and the execution time can be minimized.
• A very less number of instructional formats, a few numbers of instructions, and a few addressing modes are needed.
• Expensive, relatively complex and no flexibility of adding new instructions.

2012

Describe the working principle of binary incrementer.

- Binary incrementer is a device which can add '1' with any binary number and increment the number by '1'.  For instance, if the number is 1001 then, the binary incrementer can increment it by 1 and produce the value 1010.  To build a binary incrementer, half adders  are used. For 'n' bits of binary number we need 'n' numbers of half adder. At the first half adder we give a constant logic 1. Then the constant 1 is added with the lsb of the binary number and sum and carry will be generated. then the carry will be provided to the second half adder as one of the input and more significant bit of that binary number will be taken as the second input, this also produce one sum and one carry. This carry will also provided to the third half adder. This process will continue until the msb of the binary comes.

2014 

Convert the following expression into Reverse Polish Notation and show the evaluation procedure in the stack organized CPU.  A * B + C * ( D + E ).

- Reverse Polish Notation: 

    A B * C D E + * +

Evaluation procedure in stack: 

    PUSH A

    PUSH B

    MUL

    PUSH C

    PUSH D

    PUSH E

    ADD

    MUL

    ADD

    POP