Microprocessor · Unit 5 · 6 hrs
Basic I/O, Memory R/W and Interrupt Operations
Exam-focused notes for Basic I/O, Memory R/W and Interrupt Operations (Microprocessor, CSC167): what the TU syllabus asks and how it has actually been tested, with 10 solved past questions from this unit.
What this unit covers
- Memory Read
- Memory Write
- I/O Read
- I/O Write
- Direct Memory Access
- Interrupt
- Types
- Interrupt Masking
Interrupt Masking
What do you mean by vectored interrupt? Explain maskable and non-maskable interrupts in 8085 microprocessor. [5]
--- A vectored interrupt is an interrupt in which the interrupting device not only signals the processor for attention but also identifies itself by providing the address (vector) of its Interrupt Service Routine (ISR) directly. - When a vectored interrupt ...
Full solved answer →Write short notes on (any two):a. Program Counter b. Von-Neumann Architecture c. Interrupt Masking [5]
--- The Program Counter (PC) is a 16-bit special-purpose register in the 8085 microprocessor. It is one of the most important registers in the CPU and plays a central role in program execution. - The PC holds the memory address of the next instruction to be...
Full solved answer →What is the significance of interrupt masking? Difference between vectored and polled interrupt. [5]
--- Interrupt masking is the ability of the processor to enable or disable (mask) certain interrupts so that the CPU can decide whether to respond to an interrupt immediately or delay its response. Key significance: - Maskable Interrupts: These interrupts c...
Full solved answer →Direct Memory Access
What do you mean by Isolated I/O? Explain basic DMA operation in brief. [5]
--- Isolated I/O (also called I/O-mapped I/O) is a method of connecting I/O devices to the system where the I/O devices have a separate address space from the memory address space. - The CPU uses dedicated I/O instructions (such as IN and OUT) to communicat...
Full solved answer →Write short notes on (Any TWO):a. LDT b. DMA c. Assemble directives [5]
--- LDT is a memory management structure used in protected mode of x86 processors (such as the 8086/80286 and above). - In protected mode, memory is managed using descriptors -- entries that define the base address, size (limit), and access rights of a memo...
Full solved answer →Differentiate between interrupt based I/O and DMA based I/O. Explain based DMA operation in brief. [5]
Aspect Interrupt Based I/O DMA Based I/O --------- CPU Involvement CPU is interrupted and handles each data transfer CPU is minimally involved; DMA controller handles transfer Data Transfer Data passes through CPU registers Data transfers directly between m...
Full solved answer →Describe the working mechanism of DMA. Draw the internal architecture of the 8237 DMAC along with a timing diagram illustrating the process of DMA transfers.[10]
Direct Memory Access (DMA) is a technique that allows peripheral devices (such as disk drives, network cards, etc.) to transfer data directly to/from main memory without involving the CPU for each byte of data transfer. This significantly improves system pe...
Full solved answer →What is the importance of direct memory access? Explain the mechanism of direct memory access. [5]
Direct Memory Access (DMA) is a technique that allows external I/O devices to communicate directly with the memory without involving the processor every time. Its importance includes: 1. Frees the CPU: The CPU does not need to supervise every data transfer ...
Full solved answer →Interrupt
Write short notes on:a. RS-232 b. Interrupts [5]
--- RS-232 (Recommended Standard 232) is a standard for serial communication transmission of data between a Data Terminal Equipment (DTE) and Data Communication Equipment (DCE). It is one of the most widely used serial communication interfaces in computers ...
Full solved answer →Memory Read
Explain memory read operation with suitable figure. [5]
A memory read operation is the process by which the microprocessor retrieves (reads) data stored at a specific memory location and brings it into the processor for further processing. This operation involves coordinated use of the address bus, data bus, and...
Full solved answer →Make Unit 5 stick
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