Computer Artitecture

DIFFERENTIATE BETWEEN RISC AND CISC ARTCHITECTURE

RISC and CISC are two different types of computer processors. RISC processors are simple and fast, but they can only do basic tasks. CISC processors are more complex and can do more tasks at once, but they are slower. RISC processors are good for small devices like phones, while CISC processors are good for bigger devices like computers.

EXPLAIN WITH AN EXAMPLE , HOW EFFECTIVE ADDRESS IS CALCULATED IN DIFFERENT TYPES OF ADDRESSING MODES?

Effective address is the memory location used by a computer processor to access data. It's determined by the addressing mode used in an instruction. There are different types of addressing modes:

1. Immediate addressing: The operand is in the instruction itself, so the effective address is the operand.

2. Register addressing: The operand is in a register, so the effective address is the contents of the register.

3. Direct addressing: The operand is at a memory address specified in the instruction, so the effective address is the memory address.

4. Indirect addressing: The operand is at a memory address stored in a register, so the effective address is the contents of the memory location pointed to by the register.

5. Indexed addressing: The operand is at a memory address calculated by adding a constant or another register to the contents of a register, so the effective address is the sum of the contents of the registers or the constant and the contents of the register.

The calculation of effective address varies depending on the addressing mode used in the instruction

EXPLAIN THE CONCEPT OF GENERAL REGISTER ORGANIZATION USING PROPER EXAMPLE

General register organization is how computer processors organize and use registers. Registers are small, fast memory locations used to store and manipulate data. In general register organization, registers are not tied to any particular function and can be used for any purpose. They are typically numbered and have a specific size.

For example, in the x86 architecture, there are general-purpose registers, like EAX, EBX, ECX, EDX, EBP, ESP, ESI, and EDI. These registers can be used for storing data, arithmetic operations, or addresses.

A program can use general register organization by moving values into registers and performing calculations on them. Because the registers can be ppppppp for any purpose, they provide a flexible and efficient way to manipulate data.

EXPLAIN ALL THE PHASES OF INSTRUCTION CYCLE

The instruction cycle, also known as the fetch-pdecode-execute cycle, is the basic process that a computer processor follows to execute instructions. It consists of four phases:

1. Fetch: The processor fetches the next instruction from memory.

2. Decode: The processor decodes the instruction to determine the operation and operands required.

3. Execute: The processor performs the operation specified by the instruction, using the operands determined in the decode phase.

4. Write Back: The result of the execute phase is written back to memory or a register, depending on the instruction.

The cycle repeats for each instruction in the program until the program is complete.

In short, the instruction cycle is the process by which a computer processor executes instructions. It consists of fetching the instruction from memory, decoding it, executing the operation, and writing the result back to memory

WHAT IS INSTRUCTION - LEVEL PARALLELISM?

Instruction-level parallelism is a technique used in computer architecture to improve the performance of a processor by executing multiple instructions simultaneously. This is done by breaking down the instruction cycle into smaller stages and executing different instructions in parallel. This technique can lead to better use of the processor's resources and faster execution of instructions, but it requires careful analysis to ensure that it does not affect the correctness of the program.

GIVE THE COMPARISON BETWEEN HARDWIRED CONTROL UNIT AND MICRO PROGRAMMED CONTROL UNIT

Hardwired control unit and microprogrammed control unit are two types of control units used in computer architecture to control the operation of the processor. Here's a comparison between the two:

1. Design: The hardwired control unit is designed using a combinational logic circuit, whereas the microprogrammed control unit is designed using microcode stored in control memory.

2. Flexibility: The microprogrammed control unit is more flexible than the hardwired control unit, as it can be easily modified by changing the microcode. In contrast, the hardwired control unit is more difficult to modify because it involves changing the circuit design.

3. Complexity: The microprogrammed control unit is more complex than the hardwired control unit, as it requires an additional layer of microcode. The hardwired control unit is simpler because it uses a combinational logic circuit.

4. Speed: The hardwired control unit is generally faster than the microprogrammed control unit, as it does not need to fetch microcode from control memory. In contrast, the microprogrammed control unit needs to fetch microcode from memory, which can slow down the operation of the processor.

5. Development time: The microprogrammed control unit has a shorter development time than the hardwired control unit, as it does not require as much time to design and test the circuit. In contrast, the hardwired control unit is more time-consuming to design and test.

In summary, the microprogrammed control unit is more flexible and easier to modify, but it is more complex and slower than the hardwired control unit. The hardwired control unit is simpler and faster, but it is more difficult to modify and requires more time to develop

DESCRIBE IN DETAILS ABOUT ASSOCIATIVE MEMORY

Associative memory is a type of computer memory that retrieves data based on its content, rather than its location. It is used in applications that require fast search and retrieval of information, such as databases and network routers. There are two main types of associative memory:

fully associative memory and content-addressable memory.

In fully associative memory, the search key can be matched against any of the tags in the memory,

while in content-addressable memory, the search key is used to directly access the corresponding memory location

COMPARE PROCESS AND THREADS

Sure, here are the main points in a simplified and shortened format:

• Processes and threads are units of execution in a computer program.
• A process is an instance of a program being executed, while a thread is a lightweight unit of execution within a process.
• Each process has its own memory space, while threads share the same memory space as their parent process.
• Switching between threads is faster and requires less overhead than switching between processes.
• Inter-thread communication is faster and simpler than inter-process communication.
• Processes are scheduled by the operating system, while threads can be scheduled by either the operating system or the application.
• Processes provide greater isolation and security, while threads are faster and more lightweight.

ELABORATE THE CONCEPT OF INTERNAL FORWARDING AND REGISTER TAGGING USING AN APPROPRIATE EXAMPLES

Internal forwarding and register tagging are techniques used in computer architecture to improve the performance of pipelined processors.

Internal forwarding, also known as bypassing, is a technique that allows a result produced by an instruction in one stage of the pipeline to be forwarded directly to a later stage, instead of waiting for it to be written back to a register file and then read again. This reduces the number of pipeline stalls and improves overall performance.

Register tagging, also known as register renaming, is a technique that allows multiple instructions to write to the same register without causing a data hazard. It works by assigning a unique tag to each register read or written by an instruction. When an instruction writes to a register, it is assigned a new physical register with a different tag. This physical register is used to store the result of the instruction, while the original logical register is still used to identify the data being manipulated. This allows multiple instructions to write to the same logical register without causing a data hazard, and improves the efficiency of the pipeline

CONSIDER A PIPELINE HAVING 4 PHRASES WITH DURATION 60,50,90 AND 80 ns . Given latch delays in 10 ns calculate.
(a) pipeline cycle time
(b) non-pipeline execution time

(a) The pipeline cycle time is the maximum duration of any phase in the pipeline. Therefore, the pipeline cycle time is 90 ns.

(b) The non-pipeline execution time is the sum of the duration of each phase plus the latch delay. Therefore, the non-pipeline execution time is:

60 ns + 10 ns + 50 ns + 10 ns + 90 ns + 10 ns + 80 ns + 10 ns = 280 ns

Note that the latch delay is added twice for each phase except the first and the last, since each latch connects two phases.

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COMPUTER ARTITECTURE

 

COMPUTER INSTRUCTIONS TYPES: FORMATS, INSTRUCTION CYCLES & SUB-CYCLES

Details: Computer instructions are of three types - data movement instructions, ALU instructions, and control instructions. Instruction formats express various characteristics of instructions such as instruction code, operand type, and operand location. ALU instructions process one data to another data, while control instructions control the flow of the computer program.

The instruction cycle is divided into two parts - fetch cycle and execute cycle. In the fetch cycle, the computer fetches instructions from memory and decodes them so that the computer can execute them. In the execute cycle, the instruction is processed and then the fetch cycle starts again for the next instruction.

The instruction cycle is divided into three sub-cycles - fetch, decode, and execute.

MICRO OPERATIONS AND EXECUTIONS OF COMPLETE INSTRUCTION

When a computer performs a task, it uses a set of instructions that tell it what to do. These instructions are broken down into smaller operations called "micro operations." These micro operations include things like transferring data between different parts of the computer, doing math operations like addition or subtraction, and performing logical operations like checking if something is true or false.

When the computer runs a program, it follows a specific order of instructions. Each instruction is broken down into micro operations, which the computer carries out one at a time. The order in which these micro operations are executed is determined by the control unit of the computer.

The entire process of executing an instruction involves several steps. First, the computer fetches the instruction from memory. Then, it decodes the instruction to understand what it is supposed to do. Next, the computer executes the micro operations that make up the instruction. Finally, the result of the instruction is stored in memory or sent to another part of the computer.

The execution of an instruction can take several clock cycles, which are the basic unit of time in a computer. The number of clock cycles needed to execute an instruction depends on the complexity of the instruction and the speed of the computer.

Overall, the execution of instructions is an important part of how computers work. By breaking down instructions into smaller micro operations, computers are able to perform complex tasks quickly and efficiently.

unit -2

concept of programme - process

A program-process is a set of instructions that a computer system follows to do something. It's like a recipe for a computer. You give it some input (like ingredients), and the program-process uses that input to produce an output (like a cooked dish).

The program-process uses data storage to keep track of information it needs, and processing to manipulate and change the data to produce the output. Programs can be simple, like a calculator, or complex, like software that manages a large database of information.

Overall, program-processes are important because they help computers do all sorts of tasks quickly and accurately, like storing and organizing data, performing calculations, and running applications.

threads

A thread is like a mini-program that can run independently within a larger program, allowing for faster processing. Multiple threads can run at the same time, but they share the same resources. Threads are useful for multi-tasking environments but can create problems if not synchronized correctly.

concurrent and parallel execution

Concurrent execution means a computer system can work on multiple tasks at the same time, switching quickly between them. Parallel execution means using multiple processors or cores to perform multiple tasks simultaneously.

Concurrent execution is like a chef cooking multiple dishes at the same time by quickly switching between them. Parallel execution is like multiple chefs cooking separate dishes simultaneously to serve customers faster.

Concurrent execution is good for handling multiple users or processes running at the same time, while parallel execution is good for computationally intensive tasks

classsifications of parallel artitecture: Flynn's & Feng's Classfication

There are two common ways to classify parallel computer architectures: Flynn's taxonomy and Feng's classification.

Flynn's taxonomy classifies architectures based on how many instructions and data streams are processed at the same time. There are four categories: SISD (one instruction, one data), SIMD (one instruction, multiple data), MISD (multiple instructions, one data), and MIMD (multiple instructions, multiple data).

Feng's classification, on the other hand, classifies architectures based on how the processors and memory are organized. There are three categories: shared memory (multiple processors share a common memory), distributed memory (each processor has its own local memory), and hybrid (a combination of shared and distributed memory).

Both classifications are useful for understanding the different types of parallel architectures and their applications

basic pipelining concepts : performance metrics & measures and speed up performance laws

Pipelining is a technique used in computer processors to make them faster. It works by breaking down the tasks involved in executing a program into smaller pieces, which can be executed simultaneously. This makes the program run faster.

There are three main performance measures to evaluate how well pipelining is working: throughput, which measures how many instructions are executed per unit of time; latency, which measures how long it takes to execute one instruction; and cycles per instruction (CPI), which measures how many clock cycles are required to execute one instruction.

There are two laws that describe how much performance improvement can be gained from pipelining: Amdahl's Law and Gustafson's Law. Amdahl's Law says that the maximum speedup possible from pipelining is limited by the part of the program that cannot be parallelized. Gustafson's Law says that as the size of the program increases, more parallelism can be used, leading to greater speedup

principle of pipelining

Pipelining is a way to make computer processors faster by breaking down instruction execution into smaller stages and executing them in parallel. This allows the processor to handle multiple instructions at the same time and improves performance.

To achieve this, instructions are divided into stages such as fetch, decode, execute, memory access, and writeback. Multiple instructions are executed simultaneously, with each instruction at a different stage of the pipeline. Control hazards are handled by predicting the outcome of a branch and fetching the next instruction accordingly.

Pipelining works by breaking down instruction execution into smaller stages, executing them in parallel, and reordering the instructions before they are written back to memory. Overall, pipelining improves performance by allowing multiple instructions to be executed simultaneously

general structure of pipelines

A pipeline is a way to execute instructions in a computer processor by breaking down the execution process into several stages. The general structure of pipelines includes five stages: Instruction Fetch, Instruction Decode, Execution, Memory Access, and Write Back.

The first stage, Instruction Fetch, retrieves the instruction from memory. The second stage, Instruction Decode, decodes the instruction to determine what operation it performs. The third stage, Execution, performs the operation specified by the instruction. The fourth stage, Memory Access, accesses memory to read or write data. The fifth stage, Write Back, writes the result of the operation back to memory or a register.

Additional stages, such as Address Calculation or Register Fetch, may be added to handle more complex instructions or improve performance. The purpose of a pipeline is to execute multiple instructions simultaneously, with each stage designed to be independent of the others, allowing them to operate in parallel

classification of pipeline processors

Pipeline processors can be classified into different types based on various criteria. Here are some common classification schemes:

1. Single-issue pipeline: This type of pipeline processor can only execute one instruction at a time.

2. Multiple-issue pipeline: This type of pipeline processor can execute multiple instructions at the same time.

3. Superscalar pipeline: This type of pipeline processor can execute multiple instructions per clock cycle by using multiple execution units.

4. VLIW (Very Long Instruction Word) pipeline: This type of pipeline processor executes multiple operations in parallel by packing them into a single instruction word.

5. SIMD (Single Instruction Multiple Data) pipeline: This type of pipeline processor executes the same operation on multiple pieces of data simultaneously.

6. MIMD (Multiple Instruction Multiple Data) pipeline: This type of pipeline processor can execute different instructions on different pieces of data simultaneously.

7. Dynamic pipeline: This type of pipeline processor can dynamically adjust its pipeline stages based on the instructions being executed.

These classification schemes are not mutually exclusive and pipeline processors can have features from multiple types. The choice of pipeline type depends on the specific application and performance requirements

general pipeline and reservation tables

A pipeline is a series of steps or stages that data or information flows through in order to achieve a desired outcome. In the context of computing, pipelines are commonly used to process and transform data in a structured and efficient manner.

A reservation table is a table that keeps track of reserved resources, such as seats on an airplane or tables at a restaurant. Reservation tables typically contain information about the reservation, such as the name of the person who made the reservation, the date and time of the reservation, and any other pertinent details.

In the context of computing, a general pipeline might involve the following steps:

1. Input: Data is collected from various sources and fed into the pipeline.
2. Preprocessing: The data is cleaned, normalized, and transformed into a format suitable for further processing.
3. Analysis: The data is analyzed using statistical or machine learning algorithms to identify patterns or insights.
4. Modeling: Models are built based on the insights obtained from the analysis.
5. Evaluation: The models are evaluated and refined based on their performance.
6. Deployment: The models are deployed in a production environment where they can be used to make predictions or generate insights.

In the context of a reservation system, a reservation table might include the following information:

1. Reservation ID: A unique identifier for the reservation.
2. Name: The name of the person who made the reservation.
3. Date and Time: The date and time of the reservation.
4. Party Size: The number of people in the party.
5. Contact Information: The contact information of the person who made the reservation.
6. Notes: Any special requests or notes about the reservation.

This information can then be used to manage reservations and ensure that resources are properly allocated and reserved for the appropriate parties

principle of designing pipelined processor : pipeline instruction execution

Each instruction is divided into several stages such as instruction fetch, instruction decode, operand fetch, execute, and write back. These stages are performed in parallel with the corresponding stages of other instructions, which helps to speed up the overall execution of the instructions.

To design a pipelined processor, certain principles need to be followed. These include designing the instruction set architecture (ISA) in a way that minimizes dependencies between instructions, balancing the time taken by each stage of the pipeline, using hazard detection logic to prevent conflicts between instructions, and using forwarding to pass results directly to later stages when needed.

By following these principles, a well-designed pipelined processor can greatly improve the performance of a computer system

principle of designing pipelined processor : pre-fetched buffer

One of the main challenges in designing a pipelined processor is making sure that it always has something to work on.

To solve this problem, a pre-fetched buffer can be used. This is like a small storage area that stores the next task that the processor needs to perform before it actually needs to do it. By doing this, the processor can get started on the next task immediately after it finishes the current one, which helps it to work more efficiently and quickly.

The size of the pre-fetched buffer is important because if it is too small, the processor might have to wait for new tasks to be fetched from memory, which can slow it down. However, if the buffer is too large, it can be expensive and take up too much space. So, the right size depends on finding a balance between performance and cost.

Overall, a pre-fetched buffer is a simple but important component in designing a pipelined processor, because it helps the processor to keep working without interruptions, which makes it faster and more efficient

principle of designing pipelined processor : internal forwarding and register tagging

to improve performance. However, this approach can cause problems when an instruction needs data that has not yet been processed by a previous stage in the pipeline.

To address this issue, pipelined processors use two techniques: internal forwarding and register tagging. Internal forwarding sends data directly from one stage of the pipeline to another stage that needs it, skipping intermediate stages. Register tagging adds information to registers to indicate which stage in the pipeline last wrote to them. When an instruction needs data from a register, it checks the tag to determine if the data is still valid or if it needs to wait for the previous instruction to complete.

These techniques help the processor handle data dependencies more efficiently, which can improve performance. However, they also add complexity and overhead to the processor, which must be carefully managed to ensure that the benefits outweigh the costs.

hazard detection & resolution in pipeline processing

Pipeline processing is a method of processing data in stages, where each stage is processed by a separate component. Hazards such as data corruption or loss can occur due to errors in the input data, software bugs or hardware failures. To detect and resolve these hazards, techniques such as error-detection algorithms, redundancy, fault-tolerant hardware, and error-correction codes can be used. Hazard resolution involves techniques such as automatic reprocessing of data or manual intervention to identify and correct errors. These techniques are important for ensuring the safety and reliability of the system.

SCHEDULING PROBLEM -

Scheduling problems in pipelines refer to determining the order in which tasks should be executed in a pipeline, while taking into account their dependencies and resource requirements.

The main approaches to solving scheduling problems are:

1. Heuristics: Using rules of thumb or experience to find a good solution quickly.

2. Dynamic programming: Breaking down the problem into smaller sub-problems to find the optimal order in which to execute tasks.

3. Integer programming: Formulating a mathematical model to find the optimal sequence of tasks to execute.

4. Constraint programming: Specifying a set of constraints and finding a solution that satisfies all the constraints.

Overall, the approach to solving scheduling problems in pipelines will depend on the specific constraints and objectives of the problem at hand

collision vector in pipeline processing

A collision vector in pipeline processing is a binary vector that detects dependencies between tasks in a pipeline. Each element corresponds to a task, and a value of 1 indicates that the task has a dependency on another task. To construct a collision vector, we examine each task's inputs and outputs and mark the corresponding element in the vector as 1 if a task's output is required as an input to another task.

Collision vectors are useful for detecting and resolving dependencies, determining the order in which tasks should be executed, identifying potential bottlenecks, and scheduling tasks to avoid conflicts. They ensure that all dependencies are satisfied and the pipeline runs efficiently.

In short, collision vectors help manage dependencies in pipeline processing, making it easier to optimize the pipeline's performance

state diagram of pipeline processing

A state diagram of pipeline processing shows the different states that a task can be in as it moves through the pipeline. Typically, the states include:

1. Input: The task is waiting for input data before it can begin processing.

2. Processing: The task is actively processing the input data.

3. Output: The task has completed processing and is waiting to output its results.

4. Idle: The task is not currently processing any data.

5. Blocked: The task is blocked, waiting for input data or resources from another task.

6. Complete: The task has completed processing and has output its results.

The state diagram is a useful tool for visualizing the flow of tasks through the pipeline and identifying potential bottlenecks or performance issues. It can help to optimize the pipeline's performance and ensure that all tasks are executed efficiently.

pipeline scheduling optimization

Pipeline scheduling optimization is the process of improving the performance and efficiency of a pipeline by optimizing the scheduling of tasks. This involves techniques such as parallel processing, task prioritization, resource allocation, optimization algorithms, and heuristics. The goal is to minimize the time it takes for tasks to complete while ensuring that all dependencies are satisfied. By finding the most efficient way to execute tasks in a pipeline, we can reduce the overall time it takes for tasks to complete, improving the pipeline's performance and efficiency

Multiple vector task dispatching in pipeline processing

Multiple vector task dispatching is a technique used in pipeline processing to improve performance by executing multiple tasks simultaneously. The technique involves breaking down a large task into smaller tasks that can be executed in parallel. The smaller tasks are grouped into multiple vectors, each assigned to a separate processor or thread for execution. Multiple vector task dispatching is especially useful when working with large data sets that can be processed in parallel. It can reduce the overall time it takes for tasks to complete and improve the performance of the pipeline

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