All questions of Embedded Processors & Memory for Computer Science Engineering (CSE) Exam

In computing, a physical address (also real address, or binary address), is a memory address that is represented in the form of a binary number on the address bus circuitry in order to enable the data bus to access a particular storage cell of main memory, or a register of memory mapped I/O device.hence,option (A) is correct.

SRAM is faster than other memories

SRAM (Static Random Access Memory) is a type of memory that has more speed in accessing data compared to other memories. This can be explained by the following reasons:

1. Architecture: SRAM has a different architecture compared to other memories. It uses a flip-flop circuit to store data, which allows for faster access times. On the other hand, DRAM (Dynamic Random Access Memory) uses a capacitor to store data, which requires more time to access.

2. Access time: SRAM has a faster access time compared to other memories. It takes only a few nanoseconds to access data from SRAM, while DRAM takes around 60 nanoseconds. This makes SRAM ideal for applications that require fast access to data.

3. Power consumption: SRAM consumes less power compared to other memories. This is because SRAM does not require constant refreshing of data like DRAM, which consumes more power.

4. Cost: SRAM is more expensive compared to other memories, but it is still preferred for applications that require high speed and low power consumption.

Conclusion

In conclusion, SRAM has more speed in accessing data compared to other memories due to its architecture, access time, power consumption, and cost. This makes it ideal for applications that require fast access to data and low power consumption.

Explanation:

CISC Architecture:
CISC stands for Complex Instruction Set Computer. In CISC architecture, the processor supports a large set of complex instructions that can perform multiple low-level operations in a single instruction.

Zilog Z80 Processor:
The Zilog Z80 processor is an 8-bit microprocessor that follows the CISC architecture. It was widely used in the 1970s and 1980s in various devices like computers, game consoles, and industrial equipment.

Characteristics of CISC Architecture:
- Supports a large set of complex instructions
- Can perform multiple low-level operations in a single instruction
- Typically used in older processors

Conclusion:
Out of the given options, the Zilog Z80 processor is the one that has CISC architecture. It is important to understand different processor architectures to optimize the performance of software running on them.

Content-Addressable Memory (CAM)

Content-Addressable Memory (CAM) is a type of computer memory that allows for the direct retrieval of data based on its content rather than its address. It is also known as Associative Memory or Associative Storage. CAM is a special type of memory that provides fast data search and retrieval capabilities, making it useful in various applications that require high-speed look-up operations.

Explanation:

Content-Addressable Memory (CAM) works differently than traditional computer memory. In conventional memory systems, data is stored in specific addresses, and to retrieve the data, the system needs to know the address where it is stored. However, in CAM, the data is stored together with its associated address, which allows for direct searching and retrieval based on the content of the data.

Key Features of CAM:

CAM has several key features that make it different from other memory types:

1. Parallel Comparison: CAM allows for parallel comparison of the search key with all stored data simultaneously. This enables fast search and retrieval operations.

2. Content-Based Addressing: CAM retrieves data based on its content rather than its address. This makes it suitable for applications where the search key is not known or needs to be matched against multiple criteria.

3. High-Speed Access: CAM provides fast access to data due to its parallel search capabilities. It can perform search operations in a single clock cycle, making it ideal for real-time applications.

4. Applications: CAM is commonly used in networking devices like routers and switches for fast packet routing and filtering. It is also used in databases, cache memories, pattern matching, and content-based search systems.

Conclusion:

In conclusion, CAM stands for Content-Addressable Memory, which is a type of computer memory that allows for direct retrieval of data based on its content. CAM provides fast search and retrieval capabilities, making it useful in various applications that require high-speed look-up operations. It works by storing data together with its associated address, enabling parallel comparison and content-based addressing. CAM is commonly used in networking devices and other applications that require efficient data search and retrieval.

Introduction:
The storage element used by both MAC and IBM PC is CMOS. CMOS stands for Complementary Metal-Oxide-Semiconductor, which is a type of semiconductor technology used to store data in electronic devices.

Explanation:
- CMOS: CMOS is a type of integrated circuit technology that uses both NMOS (N-type Metal-Oxide-Semiconductor) and PMOS (P-type Metal-Oxide-Semiconductor) transistors to store information. It is commonly used for storing settings, data, and BIOS information in computers.
- MAC: MAC, which stands for Media Access Control, is a term used to refer to Apple Macintosh computers. These computers use CMOS technology for storing various settings and information. This includes BIOS settings, date and time, NVRAM (Non-Volatile Random Access Memory) data, and other system-specific information.
- IBM PC: IBM PC refers to personal computers manufactured by IBM (International Business Machines) and other compatible manufacturers. Similar to MAC, IBM PCs also use CMOS technology for storing various system settings and data. This includes BIOS settings, date and time, configuration parameters, and other system-specific information.

Advantages of CMOS:
- Low Power Consumption: CMOS technology is known for its low power consumption, making it ideal for use in devices that require long battery life.
- High Integration Density: CMOS technology allows for high integration density, meaning that a large number of transistors can be packed into a small area on a chip. This enables the creation of complex integrated circuits with a small form factor.
- Non-Volatile Memory: CMOS memory is non-volatile, which means that it retains its stored information even when power is removed. This is important for storing critical system settings and data that should not be lost during power cycles or system shutdowns.

Conclusion:
In conclusion, both MAC and IBM PC use CMOS technology as the storage element. CMOS provides advantages such as low power consumption, high integration density, and non-volatility, making it suitable for storing various system settings and data in electronic devices.

Introduction:
The architecture that is specifically designed to speed up the processor is the Reduced Instruction Set Computing (RISC) architecture. RISC architecture focuses on simplicity and efficiency by using a smaller set of instructions that are executed in a single clock cycle. This allows for faster processing and improved performance compared to other architectures.

Explanation:
RISC architecture is designed to optimize the execution of instructions, resulting in faster processing. Here's a detailed explanation of why RISC architecture is made to speed up the processor:

1. Simplicity and Reduced Instruction Set:
RISC architecture follows the principle of using a reduced instruction set. It uses a small set of simple and highly optimized instructions, typically around 100 to 200 instructions. By having a smaller instruction set, the processor can decode and execute instructions more quickly.

2. Single Clock Cycle Execution:
RISC architecture emphasizes executing instructions in a single clock cycle. Each instruction is designed to be completed in a fixed number of clock cycles, typically one clock cycle per instruction. This reduces the number of cycles required to execute complex instructions, resulting in faster processing speed.

3. Register-Based Architecture:
RISC architecture uses a large number of general-purpose registers. These registers are directly accessible by the instructions, allowing for faster data access and manipulation. With more registers available, the processor can avoid accessing memory frequently, which is slower compared to register operations.

4. Pipelining:
RISC architecture supports pipelining, which is a technique that allows multiple instructions to be executed simultaneously in different stages of the pipeline. Pipelining divides the instruction execution into several stages, such as fetch, decode, execute, and write back. This overlapping of instructions enables better utilization of the processor's resources and improves overall performance.

5. Reduced Complexity:
RISC architecture simplifies the processor design by reducing the complexity of the instructions and focusing on a streamlined execution process. This reduced complexity leads to a smaller chip size, lower power consumption, and improved efficiency.

Conclusion:
In summary, the RISC architecture is specifically designed to speed up the processor by using a reduced instruction set, executing instructions in a single clock cycle, utilizing register-based operations, supporting pipelining, and reducing the overall complexity. These design choices result in faster processing, improved performance, and better utilization of the processor's resources.

Accessing Expanded Memory in 80286
Accessing expanded memory in 80286 is typically done through Paging.

Paging
- Paging is a memory management scheme in which the computer's operating system retrieves data from secondary storage in blocks called pages.
- In the case of the 80286 processor, paging is used to access extended memory beyond the 1 MB limit of conventional memory.
- The processor uses the A20 gate to enable access to memory above the 1 MB limit, allowing paging to access expanded memory.
- The paging mechanism allows the processor to map virtual memory addresses to physical memory addresses, enabling the use of expanded memory in a controlled and efficient manner.
In conclusion, accessing expanded memory in 80286 involves the use of paging, a memory management scheme that allows the processor to access memory beyond the traditional 1 MB limit.

The coprocessor of the 8086 processor is the 8087 coprocessor. The 8087 is also known as the math coprocessor or the numeric data processor. It is specifically designed to perform mathematical operations and enhance the computational capabilities of the 8086 processor.

Below are the reasons why the 8087 coprocessor is the correct answer:

1. Enhanced mathematical capabilities:
- The 8087 coprocessor is specifically designed for handling mathematical operations efficiently.
- It provides hardware support for floating-point arithmetic, which is essential for complex mathematical calculations.
- With the 8087 coprocessor, the 8086 processor can offload complex mathematical computations and achieve faster and more accurate results.

2. Data processing efficiency:
- The 8087 coprocessor operates in parallel with the 8086 processor, allowing simultaneous execution of instructions.
- It can execute floating-point instructions independently, which reduces the burden on the main processor and improves overall system performance.
- The coprocessor's efficient data processing capabilities make it ideal for applications that involve scientific calculations, engineering simulations, financial analysis, and more.

3. Specific compatibility:
- The 8087 coprocessor is designed to work specifically with the 8086 processor.
- It utilizes a dedicated instruction set and communicates with the 8086 processor through a specialized bus interface.
- The coprocessor is physically connected to the 8086 processor via a socket, allowing for easy integration and compatibility.

4. Upgradability:
- The 8087 coprocessor can be added to a system that already has an 8086 processor, providing an upgrade path for enhanced mathematical capabilities.
- This upgradability allows users to improve the performance of their system without needing to replace the entire processor.

In conclusion, the 8087 coprocessor is the correct answer as it provides enhanced mathematical capabilities, efficient data processing, specific compatibility with the 8086 processor, and the ability to upgrade existing systems for improved performance.

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Stack Access:
Accessing a stack is primarily done through the use of a stack pointer. The stack pointer is a special register in the CPU that keeps track of the top of the stack.

Explanation:
- Stack Pointer:
The stack pointer is a register that points to the top of the stack in memory. When pushing elements onto the stack, the stack pointer is incremented to point to the next available memory location. When popping elements off the stack, the stack pointer is decremented to retrieve the topmost element.
- Operation:
To access elements in a stack, the stack pointer is used to navigate the stack. Pushing and popping elements onto and off the stack involves updating the stack pointer accordingly.
- Stack Memory:
The stack is a special region of memory that is organized as a Last-In-First-Out (LIFO) data structure. This means that the most recently added element is the first one to be removed.
- Stack Operations:
Common stack operations include push (adding an element to the top of the stack) and pop (removing the topmost element from the stack).
- Stack Efficiency:
Using the stack pointer to access the stack ensures efficient and fast access to elements, as it directly points to the current top of the stack.
In conclusion, the stack pointer plays a crucial role in accessing and manipulating elements in a stack data structure. By keeping track of the top of the stack, the stack pointer facilitates efficient stack operations such as push and pop.

Number of Data Lines in 256*4

To understand how many data lines are present in a 256*4 setup, let's break down the terms and their meanings.

256: This number represents the number of address lines. Address lines are used to specify the memory location or register being accessed. In this case, we have 256 address lines, which means we can address 256 different memory locations or registers.

4: This number represents the number of bits in each data line. Data lines are used to transfer data between the memory and the processor. In this case, we have 4 bits in each data line, which means we can transfer 4 bits of data at a time.

Now, let's calculate the number of data lines.

Formula: Number of data lines = 2^(number of address lines) * (number of bits in each data line)

Substituting the values:
Number of data lines = 2^(256) * 4

Calculating 2^256 is an extremely large number, beyond the capacity of a normal calculator or computer. However, we can simplify the calculation by considering the power of 2.

Power of 2:
2^1 = 2
2^2 = 4
2^3 = 8
2^4 = 16
2^5 = 32
...
2^8 = 256

From the pattern, we can see that 2^8 is equal to 256. This means that 2^(256) is a very large number.

Now, let's calculate the number of data lines using the simplified formula:

Number of data lines = 256 * 4

Simplifying further:

Number of data lines = 1024

Therefore, the correct answer is option 'C' - 4.

Shifting the segment by 4 helps in finding the physical address in 8086.

Explanation:
In 8086 architecture, the physical address is calculated by combining the segment address and the offset address. The segment address is shifted left by 4 bits and then added to the offset address to form the physical address.

Here's a detailed explanation of how shifting the segment by 4 helps in finding the physical address:

1. Segmentation in 8086:
- The 8086 processor uses a segmentation scheme to address memory.
- The memory is divided into segments, each having a size of 64KB.
- There are four segment registers: CS (Code Segment), DS (Data Segment), SS (Stack Segment), and ES (Extra Segment).
- The segment registers hold the base address of the corresponding segment.

2. Calculating the physical address:
- The physical address is formed by combining the segment address and the offset address.
- The segment address is obtained from the segment register, and the offset address is obtained from a general-purpose register or a memory location.
- To calculate the physical address, the segment address is shifted left by 4 bits (equivalent to multiplying by 16) and then added to the offset address.

3. Shifting the segment by 4:
- Shifting the segment by 4 means shifting the segment address left by 4 bits.
- This is equivalent to multiplying the segment address by 16.
- Shifting the segment by 4 is done to convert the segment address from a 16-byte segment to a 20-byte segment.
- This conversion allows the segment address to be combined with the offset address, which is a 16-bit value, to form a 20-bit physical address.

4. Example:
- Let's say the segment address in the CS register is 1000H (4096 decimal) and the offset address is 0100H (256 decimal).
- Shifting the segment address by 4 (1000H < 4)="" gives="" 10000h="" (65536="" />
- Adding the offset address (0100H) to the shifted segment address (10000H) gives the physical address 10100H (65792 decimal).

Therefore, shifting the segment by 4 is the correct option for finding the physical address in 8086.