Deliverables
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Introduction to 8086 Architecture
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Today, we're discussing the architecture of the 8086 microprocessor. Can anyone tell me what differentiates the 8086 from the earlier 8085 model?
Is it because the 8086 has a 20-bit address bus that allows it to access more memory?
Exactly! The 8086 can access 1 Megabyte of memory, thanks to this 20-bit address bus. Let's recall the architecture components: Can anyone name them?
I remember the Bus Interface Unit and the Execution Unit!
Right! The BIU handles external bus operations while the EU takes care of instruction decoding and execution. Learning about these components helps us understand how data flows in microprocessors.
Letβs summarize: The 8086 architecture has two primary units, the BIU and the EU. Can anyone recap their functions?
The BIU manages bus operations and instruction fetching, while the EU is responsible for executing the instructions!
Understanding Segmented Memory
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Now let's dive into segmented memory organization. Why do you think segmented memory is important?
It helps with better memory management and organization, right?
Yes! Each segment can go up to 64 KB, and it starts at paragraph boundaries, meaning addresses that are divisible by 16. Can anyone explain how we compute a physical address from a segment and offset?
We use the formula: Physical Address = (Segment Register Value * 10H) + Offset Address.
Exactly! This calculation creates a 20-bit address. Let's do a quick example: If DS = 2000H and the offset is 0050H, what's the physical address?
That would be 20050H!
Good job! So, segmented memory allows more organized access to a larger memory space. Remember: Segmentation is key!
Addressing Modes
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Letβs talk about the different addressing modes. Why do we need various addressing modes in assembly programming?
To access data in different ways. It gives more flexibility!
Exactly! Starting with immediate addressing: an operand included in the instruction. Can anyone give me an example?
Like MOV AX, 5000H?
That's correct! Next, we have register addressing where the operand is in a register. Who can explain its usage?
It's used for quick operations, like MOV AX, BX, right?
Spot on! Direct addressing allows you to specify a memory location directly. Can you think of an example?
Sure, like MOV AX, [1234H].
Perfect! Addressing modes help us optimize how we access and manage data within different contexts.
Introduction & Overview
Read summaries of the section's main ideas at different levels of detail.
Quick Overview
Standard
The deliverables include detailed tasks that students must complete related to the 8086 microprocessor, such as understanding its architecture, memory segmentation, addressing modes, and executing assembly language programs. The section emphasizes practical execution and observation of results.
Detailed
Deliverables
Overview
This section details the deliverables expected from students after completing Experiment No. 4, focused on the 8086 microprocessor. The aim is to enhance practical understanding of the microprocessor by engaging in hands-on coding and executing assembly language programs. The students will demonstrate their understanding through various tasks related to architecture, addressing modes, and code execution.
Key Tasks
- Explanation of 8086 Architecture: A report on the internal architecture, including functional units and registers.
- Segmented Memory Use: Students must explain how segmented memory works, including detailed calculations of physical addresses.
- Addressing Modes Explanation: Describe various addressing modes utilized in the 8086 architecture with examples.
- Assembly Code with Comments: Students should provide assembly code snippets for each addressing mode, commenting on the purpose and functions of each instruction.
- Execution Screenshots: Capture screenshots illustrating the execution flow of assembly programs, demonstrating changes in register and memory states.
- Observations and Analysis: Record observations from executing each program, including initial and final states of registers and any affected flags.
Significance
By accomplishing these tasks, students will demonstrate a thorough understanding of the 8086 microprocessor's architecture and memory organization, crucial for effective low-level programming.
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Explanation of 8086 Architecture
Chapter 1 of 6
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Chapter Content
- Explanation of 8086 Architecture: (As covered in Theory, Section 3.1).
Detailed Explanation
The 8086 microprocessor architecture is structured into two main units: the Bus Interface Unit (BIU) and the Execution Unit (EU). The BIU manages bus operations involving fetching instructions and data, while the EU is tasked with decoding and executing those instructions. It maintains several registers, including segment registers, instruction pointers, and data registers, which work together to access a vast amount of memory efficiently, using a 20-bit physical address created from a 16-bit segment address and a 16-bit offset.
Examples & Analogies
Think of the 8086 architecture as a factory. The BIU is like the logistics department that fetches materials and products, while the EU is the assembly line where the actual work is done to create the final products. This separation allows for more efficient processing, just like how factories organize tasks to maximize production.
Explanation of Segmented Memory and Physical Address Calculation
Chapter 2 of 6
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Chapter Content
- Explanation of Segmented Memory and Physical Address Calculation with Numerical Example: (As covered in Theory, Section 3.2).
Detailed Explanation
The 8086 microprocessor employs a segmented memory organization, which divides its 1MB addressable memory into segments of up to 64KB each. This organization optimizes memory access and allows multiple programs to run simultaneously without interference. To calculate a physical address, a formula is used: Physical Address = (Segment Register Value * 10H) + Offset Address. For example, if the Data Segment (DS) is 2000H and the offset is 0050H, the physical address would be calculated as follows: Physical Address = (2000H * 10H) + 0050H = 20050H.
Examples & Analogies
Imagine a library where each book is segmented into shelves. Each shelf can hold a certain number of books (similar to segments). To find a specific book (the data), you must first go to the right shelf (the segment) and then locate the book within that shelf (offset). This system allows for quicker access and better organization compared to a single long row of books.
Explanation of Each Addressing Mode
Chapter 3 of 6
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Chapter Content
- Explanation of Each Addressing Mode: (As covered in Theory, Section 3.3).
Detailed Explanation
Addressing modes define how an operand's effective address is computed in the 8086 microprocessor. There are several modes, including Immediate, Register, Direct, Register Indirect, Based, Indexed, Based-Indexed, and String Addressing Modes. Each mode specifies a method to access data, which affects how instructions are executed in programs, making it crucial for optimizing performance and memory usage.
Examples & Analogies
Consider addressing modes like different routes to reach a destination. Some are direct paths (Direct Addressing), while others may involve navigating through checkpoints (Register Indirect). Immediate Addressing is like having an explicit address written down from the start. Knowing the best route means you can reach your destination (data access) quickly and effectively, utilizing the resources available.
Assembly Code with Comments
Chapter 4 of 6
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Chapter Content
- Assembly Code with Comments: For each addressing mode demonstration program (as provided in Section 5, Part B).
Detailed Explanation
Assembly code for each addressing mode provides practical examples of how operands are accessed in a program. The code includes comments that explain what each instruction does, contributing to a better understanding of how the 8086 handles different types of data access. This enhances learning by connecting theoretical knowledge with practical coding skills.
Examples & Analogies
Writing assembly code with comments is like creating a recipe that not only lists the ingredients (code instructions) but also provides detailed steps on how to prepare the dish (operations). This ensures that anyone trying to replicate the recipe can understand how to proceed at each stage, reducing the likelihood of errors.
Execution Screenshots from Simulator
Chapter 5 of 6
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Chapter Content
- Execution Screenshots from Simulator: Include screenshots showing: β Initial state of registers and relevant memory areas. β State after key instructions or the final state after program execution, clearly demonstrating the effect of the addressing mode. β (Optional but recommended) Screenshot of physical address calculation for a specific instruction if the simulator provides this debug feature.
Detailed Explanation
Screenshots from the simulator visually demonstrate the processes and results of executing the assembly code. They show the initial setup of registers and memory locations, the state at various points during execution, and the final outcomes after code execution. This reinforces the learning experience by providing tangible evidence of how the addressing modes affect data operations.
Examples & Analogies
Consider screenshots from the simulator as snapshots of a cooking process. Just like you would take pictures at various stages of preparing a meal to show how it evolves, these screenshots capture the progression of the program and illustrate how each addressing mode impacts the execution flow and data retrieval.
Detailed Observations and Analysis
Chapter 6 of 6
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Chapter Content
- Detailed Observations and Analysis: (As recorded in Section 6).
Detailed Explanation
The observations and analyses made during the experiment include the initial state of registers, changes during execution, memory contents before and after operations, and the final state of registers. This systematic documentation helps students understand the practical implications of theoretical concepts discussed earlier and reinforces their learning through real data.
Examples & Analogies
Making detailed observations in programming is akin to keeping a journal of a science experiment. Just as students document their findings, errors, and outcomes to understand the scientific process, documenting the behavior of registers and memory locations during execution helps students grasp the underlying mechanisms and improve their programming skills.
Key Concepts
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Bus Interface Unit (BIU): Handles all bus operations and instruction fetching.
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Execution Unit (EU): Responsible for decoding and executing instructions.
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Segmented Memory: Divides memory into segments for better management.
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Addressing Modes: Techniques to access and manage operands efficiently.
Examples & Applications
MOV AX, 5000H: Example of immediate addressing where data is loaded directly into a register.
MOV AX, [1234H]: Example of direct addressing accessing data from a specific memory location.
Memory Aids
Interactive tools to help you remember key concepts
Rhymes
BIU fetches and EU does decode, in 8086, they share the load.
Stories
Imagine a train station (BIU) where trains (data) are fetched, and a factory next door (EU) processes those trains and turns them into products (executed instructions).
Memory Tools
B.E.S.T - Bus Interface handles fetching, Execution executes, Segmented memory, and addressing modes assist in data access.
Acronyms
M.E.R.C. - Memory (Segmented), Execution Unit, Register modes, and Calculating addresses.
Flash Cards
Glossary
- 8086 Microprocessor
A 16-bit microprocessor characterized by its segmented memory and capable of addressing 1 MB of memory.
- Bus Interface Unit (BIU)
The part of the 8086 that handles external bus operations such as fetching instructions and reading/writing data.
- Execution Unit (EU)
The part of the 8086 that decodes and executes instructions.
- Segmented Memory
A method of dividing memory into logical segments for improved organization and management.
- Addressing Mode
A technique that determines how the effective address of an operand is calculated.
- Immediate Addressing
An addressing mode where the operand is part of the instruction itself.
- Register Addressing
An addressing mode where the operand is located within a register.
- Direct Addressing
An addressing mode that specifies the effective address of the operand directly in the instruction.
Reference links
Supplementary resources to enhance your learning experience.