Unit 2 L10 | RIM instruction | Read Interrupt Mask| RIM IN 8085 MICROPROCESSOR | Pending Interrupt

Techno Tutorials ( e-Learning)

1 Feb 202107:48

Summary

TLDRThis video script delves into the concept of RIM (Read Interrupt Mask) and FRIM (Frame Read Interrupt Mask) instructions, focusing on their use in reading the status of interrupts in a microprocessor. It explains the one-byte instruction format and clarifies the functions of the RIM, including identifying pending interrupts, displaying the status of the interrupt enable flag, and determining whether interrupts are enabled or disabled. The script also distinguishes between pending and masked interrupts, providing insights into the microprocessor's interrupt management.

Takeaways

📝 The video discusses the difference between 'rim' and 'frame' instruction in a computer program.
🔢 'One byte instruction' refers to a program instruction that uses one memory location for its execution.
📡 'RIM' stands for Read Interrupt Mask, and it is used to read the status of interrupts.
👉 The RIM instruction can identify pending interrupts, which are activated but not yet served by the microprocessor.
🔢 Bit positions in the RIM instruction (D0 to D7) represent different interrupt statuses, with specific bits indicating the status of particular interrupts.
🚫 If the D5 bit is set to one, it indicates that the interrupt at position 6.5 is in a pending condition.
🛑 Bit D3, or I4, shows the interrupt enable flag status, determining if interrupts are enabled (1) or disabled (0).
🔄 M7.5, M6.5, and M5.5 represent the masked interrupt status, showing whether an interrupt is masked (1) or unmasked (0).
🔄 D4 to D6 in the RIM instruction show the status of interrupts as pending or not.
🔄 The term 'masked interrupt' refers to an interrupt that is currently not being processed by the system due to its status in the RIM instruction.
🤔 The video ends with a prompt for the difference between pending interrupts, but does not provide the answer within the transcript.

Q & A

What is the main topic of the video?
-The main topic of the video is to discuss the difference between RIM (Register Instruction Memory) and Frame Instruction.
What does 'one byte instruction' mean in the context of the video?
-In the context of the video, 'one byte instruction' refers to an instruction that occupies one memory location and is used for executing program commands.
What is the purpose of the RIM instruction?
-The purpose of the RIM instruction is to read the status of interrupts, which helps in identifying pending interrupts and managing them accordingly.
How many bits are used to identify pending interrupts in the RIM instruction?
-Eight bits are used to identify pending interrupts in the RIM instruction, with each bit corresponding to a specific interrupt status.
What does the bit number 'D3' represent in the RIM instruction?
-In the RIM instruction, bit number 'D3' represents the interrupt enable flag status, indicating whether interrupts are enabled (1) or disabled (0).
What is the significance of the bits D4 to D6 in the RIM instruction?
-Bits D4 to D6 in the RIM instruction show the status of the interrupt enable flag, indicating whether the respective interrupts are enabled or disabled.
What does the term 'masked interrupt' refer to in the video?
-A 'masked interrupt' refers to an interrupt that has been disabled or prevented from being recognized by the microprocessor due to the corresponding bit being set to one.
How can you determine if an interrupt is pending based on the RIM instruction?
-You can determine if an interrupt is pending by checking the corresponding bit in the RIM instruction; if the bit is set to one, the interrupt is pending.
What is the difference between a pending interrupt and a masked interrupt?
-A pending interrupt is one that has occurred but has not yet been serviced by the microprocessor, while a masked interrupt is one that has been disabled and will not be recognized by the microprocessor.
How can you tell if the interrupts are enabled or disabled in the RIM instruction?
-You can tell if the interrupts are enabled or disabled by checking the value of the interrupt enable flag (D3) in the RIM instruction; a value of 1 means interrupts are enabled, and a value of 0 means they are disabled.
What does the term 'serial input data' refer to in the context of the RIM instruction?
-In the context of the RIM instruction, 'serial input data' refers to the process of receiving data in a sequential manner, one bit at a time, which is indicated by the bits D4 to D6.

Outlines

00:00

🧠 Understanding RIM and EMR Instructions

This paragraph introduces the concept of RIM (Read Interrupt Mask) and EMR (Enable Mask Register) instructions in programming. It explains that these are one-byte instructions used to manage interrupt statuses. The RIM instruction is specifically used to read the status of interrupts, identifying which interrupts are pending and which are not. The EMR instruction, on the other hand, is used to enable or disable interrupts. The paragraph delves into the bit-wise representation of these instructions, highlighting the functions of bits such as D3 (interrupt enable flag), D5 (pending interrupt status), and the masking of interrupts (D0 to D2). It also discusses the implications of these bits being set to 1 or 0, indicating whether interrupts are enabled, pending, or masked.

05:01

🔍 Exploring the Details of Interrupt Status and Masking

The second paragraph continues the discussion on interrupts, focusing on the status and masking of interrupts. It explains that the RIM instruction can read the status of multiple interrupts at once, identifying which are pending. The EMR instruction is used to enable or disable these interrupts. The paragraph further clarifies the role of bits D4 to D6 in showing the status of interrupts and the interrupt enable flag (D7.5, D6.5, D5.5). It also discusses the concept of masked interrupts, where bits D0 to D2 indicate whether an interrupt is masked (1) or unmasked (0). The paragraph ends by prompting a question about the difference between pending interrupts, inviting further exploration or clarification.

Mindmap

Keywords

💡RIM (Register Instruction Memory)

RIM stands for Register Instruction Memory, which is a concept in computer architecture referring to the memory location used to store and execute instructions. In the context of the video, RIM is used to read the status of interrupts, which is a crucial part of understanding how the microprocessor handles and responds to various signals or events. The script mentions that RIM is used to 'read the status of interrupts,' highlighting its role in managing interrupt requests.

💡Instruction

An instruction in computing is a command that a computer's processor can execute. The video script discusses 'one byte instruction,' which means that the instruction is encoded in a single byte of memory. This is significant because it affects how the processor decodes and executes the command, as well as how efficiently the program can be stored and run.

💡Interrupt

An interrupt is a signal sent to the processor to temporarily halt its current tasks and attend to a higher priority task. In the video, the script explains that RIM is used to 'read the status of interrupts,' which is essential for managing and prioritizing tasks in a computer system. The script also discusses different types of interrupts, such as 'pending interrupts,' indicating that there are multiple interrupts that need to be handled.

💡Pending Interrupts

Pending interrupts are those that have occurred but have not yet been processed by the microprocessor. The script uses the term to describe a situation where 'more than one interrupts are activated to the microprocessor.' This concept is important for understanding how the system prioritizes and schedules the handling of multiple interrupt requests.

💡Status

In the context of the video, 'status' refers to the current condition or state of a system or component. The script mentions reading the 'status of interrupts,' which involves checking whether interrupts are pending, enabled, or masked. This is crucial for the microprocessor to determine how to respond to various events.

💡Enable

To enable in computing means to activate or turn on a particular function or feature. The script discusses the 'interrupt enable flag' (d3), which indicates whether interrupts are allowed to be processed by the system. If the value is '1,' it means that interrupts are enabled, and if it is '0,' they are not.

💡Masked Interrupt

A masked interrupt is one that has been disabled or prevented from being processed by the microprocessor. The script explains that bits d0 to d2 in the RIM show the status of masked interrupts, where a '1' indicates that the particular interrupt is masked, and a '0' means it is unmasked and can be processed.

💡Serial Input Data

Serial input data refers to data that is received one bit at a time in a sequential manner. The script mentions 'receiving serial input data' (sid), which is a method of data transmission commonly used in communication protocols. This is important for understanding how data is input into the system for processing.

💡Bit

A bit is the basic unit of information in computing, representing a 0 or 1. The script frequently refers to bits, such as 'd5 bit,' 'd3,' and 'd0 to d2,' to describe the individual components of the RIM that store and convey information about the status of interrupts and their enablement.

💡Memory Location

A memory location is a specific address in a computer's memory where data or instructions are stored. The script mentions that a 'one byte instruction' is used, which implies that the instruction is stored in a single memory location. This is fundamental to how the computer processes and executes the instructions.

💡Flag

In computing, a flag is a single bit that indicates the status of a condition or an event. The script uses the term 'interrupt enable flag' to describe the status of whether interrupts are enabled or not. This is a simple yet critical mechanism for controlling the flow of execution in response to interrupts.

Highlights

The video discusses the difference between RIM and frame instruction.

One byte instruction means using one memory location for execution.

RIM is used to read the status of interrupts.

Interrupt status can be identified using bits D0 to D7.

7.5 I6.5 I5.5 shows the pending status of RST 7.5, RST 6.5, and RSD 5.5 interrupts respectively.

If D5 bit is 1, RST 6.5 is in a pending condition.

D3 (I4) shows the interrupt enable flag status.

A value of 1 for I4 means interrupts are enabled, while 0 means they are not.

M7.5, M6.5, and M5.5 show the status of interrupts - pending or not.

T (I7.5 6.5 5.5) indicates the interrupt enable flag.

A value of 1 for T means interrupts are enabled, while 0 means they are disabled.

Bits D4 to D6 show the status of masked interrupts.

If a bit is 1, the corresponding interrupt is masked. If 0, it is unmasked.

The video will explain the difference between pending and masked interrupts.

RIM instruction helps in identifying and managing interrupt statuses in a microprocessor.

Understanding RIM is crucial for effective interrupt handling in programming.

The video provides a clear explanation of RIM and its functions in interrupt management.