Model Questions and Solutions BIM 3rd Semester

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Model Question And Solution -2014

Ans: The major advantage of floating point representation are:

  • Dynamic Range.
  • Precision.
  • Portability.
  • Efficiency.

Ans: The solution of resource conflict pipeline hazard are:

  • Hardware Interlocking.
  • Pipelined Resource Allocation.
  • Compiler Optimization.
  • Static Analysis and Simulation.

Ans: An opcode is a fundamental component of machine language instructions, specifying the operation to be performed by the CPU and serving as the basis for all computational tasks executed by the computer.

Ans: The size of data register is 16 bit in Basic computer because it helps to balance simplicity, cost-effectiveness, and compatibility with the overall design goals of the system.

Ans: Here are some of the reasons why daisy chaining is required and they are :

  • Data Transfer.
  • Signal Propagation.
  • Power Distribution
  • Control and Configuration

Ans: The difference between strobe and handshaking are:

AspectsStrobe Handshaking
DefinitionIn strobe-based communication, data is transferred between devices in response to a single control signal, known as a strobe signal. In handshaking-based communication, data transfer is coordinated through a series of control signals exchanged between the transmitting and receiving devices.
ExampleParallel printer interfaces often use strobe signals to transfer data from the computer to the printer.Serial communication protocols, such as UART (Universal Asynchronous Receiver/Transmitter), often use handshaking signals like RTS (Request to Send) and a peripheral device like a modem or a serial printer.

Ans: Locality of Reference refers to the tendency of the computer program to access instructions whose addresses are near one another. Programs are said to exhibit temporal locality if they access the same memory location several times within a small window of time.

Ans: An associative memory is one in which any stored item can be accessed directly by using partial contents of the item in question. They are also commonly known as content-addressable memories (CAMs). 

Ans: In the context of a microprocessor, a process refers to a specific task or set of instructions that the microprocessor executes sequentially to perform a particular function or operation.

Ans: A loosely coupled multiprocessor, also known as a distributed multiprocessor or cluster-based multiprocessor, is a type of multiprocessing system where multiple independent processors are interconnected to work together towards a common goal.

Ans: Comparing hardwired control units (CUs) to micro-programmed control units involves considering factors such as performance, flexibility, complexity, and ease of modification. While each approach has its advantages and disadvantages, the suitability depends on the specific requirements of the computer architecture and the trade-offs involved. Here’s a comparison between hardwired and micro-programmed control units:

Hardwired Control Unit:

  1. Performance: Hardwired control units typically offer better performance because they directly implement control logic using combinational and sequential logic circuits. This means instructions can be decoded and executed more quickly since there is no overhead associated with fetching and interpreting microcode.
  2. Simplicity: Hardwired control units are generally simpler in terms of hardware complexity because they consist of dedicated hardware circuits for each control signal. This simplicity can lead to lower hardware costs and reduced power consumption.
  3. Determinism: Since the control logic is implemented directly in hardware, the behavior of a hardwired control unit is deterministic and predictable. This can be advantageous in real-time systems or applications where precise timing is critical.
  4. Limited Flexibility: Hardwired control units are less flexible than micro-programmed control units because their behavior is fixed and cannot be easily modified or updated without changing the hardware design. This can make it challenging to accommodate changes in instruction set architecture or to add new instructions.

Micro-Programmed Control Unit:

  1. Flexibility: Micro-programmed control units offer greater flexibility because control logic is implemented using microcode, which is stored in a control memory (often ROM). This allows for easier modification and customization of the control logic without changing the underlying hardware.
  2. Ease of Modification: Modifying the behavior of a micro-programmed control unit typically involves updating the microcode stored in memory, which can be done through software changes. This makes it easier to add new instructions, support different instruction set architectures, or fix bugs without requiring changes to the hardware.
  3. Complexity: Micro-programmed control units are generally more complex than hardwired control units because they require additional hardware for storing and executing microcode. This complexity can lead to higher hardware costs, increased power consumption, and potentially slower performance due to the overhead of microcode execution.
  4. Performance Overhead: Micro-programmed control units may introduce performance overhead due to the additional cycles required to fetch and execute microcode instructions. This overhead can impact the overall execution speed of instructions compared to hardwired control units.

In summary, hardwired control units offer better performance and simplicity but lack the flexibility and ease of modification provided by micro-programmed control units. The choice between the two depends on the specific requirements of the computer architecture, such as performance goals, flexibility needs, and trade-offs between hardware complexity and ease of modification.

Ans: A common bus system, also known as a shared bus architecture, is a fundamental design used in basic computer systems to facilitate communication between various components such as the CPU, memory, and I/O devices. In a common bus system, all components share a single set of communication lines, or “bus,” which allows them to exchange data and control signals.

Here’s how a common bus system typically works in a basic computer:

  1. Bus Structure: The common bus consists of multiple parallel lines or wires, each carrying a specific type of information such as data, addresses, control signals, and timing signals. These lines are shared among all components connected to the bus.
  2. CPU: The central processing unit (CPU) is the primary component of the computer responsible for executing instructions. It communicates with other components through the common bus to fetch instructions, access data from memory, and transfer data to and from I/O devices.
  3. Memory: The computer’s memory modules, such as RAM (random access memory) and ROM (read-only memory), are connected to the common bus. The CPU uses the bus to read instructions and data from memory and to write data back to memory when needed.
  4. Input/Output (I/O) Devices: Various peripheral devices, such as keyboards, mice, displays, storage devices, and network interfaces, are also connected to the common bus. The CPU communicates with these devices through the bus to send and receive data and control signals.
  5. Arbitration: Since the common bus is shared among multiple components, a mechanism is needed to control access to the bus and prevent conflicts when multiple components try to use it simultaneously. This is typically handled by a bus arbitration scheme, which determines the priority of access for different components. Common arbitration methods include centralized arbitration, distributed arbitration, and priority-based arbitration.
  6. Data Transfer: Data transfer on the common bus occurs in a parallel fashion, meaning that multiple bits of data are transferred simultaneously over multiple lines of the bus. This allows for faster data transfer compared to serial communication.
  7. Synchronization: Timing signals are used to synchronize the operation of different components connected to the common bus. These signals ensure that data is transferred at the correct time and that all components operate in harmony.
cpu

Overall, a common bus system provides a simple and efficient way for the CPU, memory, and I/O devices to communicate with each other in a basic computer architecture. However, it may become a bottleneck in more complex systems with high-performance requirements, leading to limitations in scalability and throughput.

Ans: An instruction pipeline is a technique used in modern computer processors to increase instruction throughput and overall performance by overlapping the execution of multiple instructions. It breaks down the execution of instructions into several sequential stages, allowing different stages of different instructions to be executed concurrently.

  1. Fetch: The processor fetches the next instruction from memory. This instruction is typically located at the address specified by the program counter (PC). The fetched instruction is then stored in an instruction register.
  2. Decode: The fetched instruction is decoded to determine the operation it specifies and the operands involved. This stage also involves fetching any required data from registers or memory.
  3. Execute: The decoded instruction is executed, which may involve performing arithmetic or logic operations, accessing memory, or controlling other hardware components.
  4. Memory Access: If the instruction requires accessing memory (e.g., loading or storing data), this stage handles the memory access operation.
  5. Write Back: The result of the instruction execution is written back to the appropriate register or memory location, completing the instruction.

In a pipelined processor, these stages are overlapped, meaning that while one instruction is being executed, the next instruction can be fetched, and the one after that can be decoded, and so on. This allows multiple instructions to be in various stages of execution simultaneously, improving overall throughput and performance.

However, pipeline execution can introduce hazards that may hinder performance. These hazards include:

  1. Data Hazards: Situations where an instruction depends on the result of a previous instruction that has not yet completed. This can lead to stalls or bubbles in the pipeline as the processor waits for the required data to become available.
  2. Control Hazards: Situations where the flow of execution is altered, such as due to branch instructions. Handling control hazards often requires the use of techniques like branch prediction or speculative execution to keep the pipeline filled with instructions.
  3. Structural Hazards: Situations where multiple instructions require access to the same hardware resource simultaneously, leading to contention and potential stalls.

Ans: There are various cache mapping techniques and some of them are as:

Group 17
  1. Direct Mapping:
  • Each memory block is mapped to exactly one cache line.
  • The mapping is determined by a modulo function, which maps memory addresses to specific cache lines.
  • Simple and easy to implement but may lead to cache conflicts.
image 12

2. Fully Associative Mapping:

  • Each memory block can be placed in any cache line.
  • No restrictions on the placement of memory blocks.
  • Offers maximum flexibility and minimizes cache conflicts but requires complex hardware for searching cache contents.
image 5

3. K-way Set-Associative Mapping:

  • Combines aspects of both direct mapping and fully associative mapping.
  • Memory is divided into a number of sets, and each set contains multiple cache lines.
  • Each memory block can be mapped to any cache line within its corresponding set.
  • Allows for more flexibility and reduces the chance of cache conflicts compared to direct mapping.
sm 1

Ans: Cache coherency is a situation where multiple processor cores share the same memory hierarchy, but have their own L1 data and instruction caches. In a multiprocessor system, each processor typically has its own cache memory to store frequently accessed data. When multiple processors are accessing and updating shared data in main memory, it’s crucial to ensure that the copies of this data stored in different caches remain consistent with each other.

cc

Maintaining cache coherence adds complexity to the design of multiprocessor systems but is essential for ensuring correct behavior in concurrent programs running on such systems. Cache coherence protocols and mechanisms vary depending on the architecture and design goals of the multiprocessor system.

Ans: The difference between combinational and sequential circuit are:

AspectsCombinational CircuitSequential Circuit
DefinitionCombinational circuits are digital circuits where the output depends solely on the present input values, and there is no memory or feedback involved.Sequential circuits are digital circuits where the output depends not only on the present input values but also on the past history of inputs, i.e., there is an internal state or memory element involved.
TimingCombinational circuits have no concept of clocking or timing; their outputs change immediately in response to changes in inputs.Sequential circuits have a concept of clocking. Changes in the output occur only at specific points in time synchronized with a clock signal.
Behavior The output of a combinational circuit is determined by the current combination of input values, and there is no concept of past states affecting the output.The output of a sequential circuit depends on both the current input and the current state of the circuit (which is determined by past inputs).
PerformanceAs the input of current instant is only required in case of Combinational circuit, it is faster and better in performance as compared to that of Sequential circuit.Sequential circuits are comparatively slower and has low performance as compared to that of Combinational circuit
ComplexityNo implementation of feedback makes the combinational circuit less complex as compared to sequential circuit.The implementation of feedback makes sequential circuit more complex as compared to combinational circuit
image 8

Figure of Combinational Circuit.

image 7

Figure of Sequential Circuit.

Ans: In computer architecture, an addressing mode is a technique used in the instruction set architecture (ISA) of a computer’s CPU to specify how the CPU should calculate the memory address of an operand (data) for a given instruction.

Here are some common addressing modes:

  1. Immediate Addressing:
    • The operand is a constant value or immediate data.
    • Example: MOV AX, 5 (Move the value 5 into register AX).
  2. Direct Addressing:
    • The operand specifies the address of the data directly.
    • Example: MOV AX, [1234H] (Move the value stored at memory address 1234H into register AX).
  3. Register Addressing:
    • The operand specifies a register.
    • Example: ADD AX, BX (Add the value of register BX to register AX).
  4. Indirect Addressing:
    • The operand contains the address of the memory location which holds the actual operand.
    • Example: MOV AX, [BX] (Move the value stored at the memory address pointed to by register BX into register AX).
  5. Indexed Addressing:
    • The effective address of the operand is obtained by adding a constant value or value in a register to a base address.
    • Example: MOV AX, [SI + 10] (Move the value stored at the memory address pointed to by the sum of the value in register SI and 10 into register AX).
  6. Base-Displacement Addressing:
    • Similar to indexed addressing, but the displacement value is added to a base address register.
    • Example: MOV AX, [BX + 20] (Move the value stored at the memory address pointed to by the sum of the value in register BX and 20 into register AX).
  7. Relative Addressing:
    • The operand is specified relative to the program counter (PC) or instruction pointer (IP).
    • Example: JMP LABEL (Jump to the memory address specified by the label).

These addressing modes provide flexibility and efficiency in accessing data and operands, allowing programmers to write code that is both readable and optimized for performance. The choice of addressing mode depends on the specific requirements of the instruction and the programming task at hand.

Ans: Multiply (-13) *(+40) using Booth multiplication algorithm:

let’s use the Booth multiplication algorithm to multiply -13 by +40.

First, let’s represent both numbers in binary:

-13 = 1111011 (7-bit two’s complement) +40 = 0101000 (7-bit two’s complement)

Now, we’ll set up the multiplication table:

1111011     (-13)
x  0101000     (+40)
-----------------

Next, let’s perform the Booth algorithm steps:

Step 1: Initialize the product and the accumulator with the first multiplier digit (0 in this case).

      1111011    (-13)
x     0101000    (+40)
-----------------
 P:  0000000
 A:  0000000

Step 2: Check the last digit of the multiplier and shift:

Since the last digit of the multiplier is 0, we don’t need to subtract anything. Just shift right.

      1111011    (-13)
x     0101000    (+40)
-----------------
 P:   0000000
 A:  0111101

Step 3: Repeat step 2 for the remaining digits of the multiplier.

      1111011    (-13)
x     0101000    (+40)
-----------------
 P:   1111011
 A:  0111101

Step 4: Shift right again (since we’ve exhausted all the digits of the multiplier).

      1111011    (-13)
x     0101000    (+40)
-----------------
 P:  11111011
 A:  00111101

Now, we have our product in the form of two 7-bit binary numbers:

Product: 11111011 (−5210 in decimal) Accumulator: 00111101 (+6110 in decimal)

So, (-13) * (+40) = -52 + 61 = 9.

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