Read Interrupt Mask Instruction In 8085 | RIM Instruction In 8085 Microprocessor
Summary
TLDRThis tutorial introduces the RIM (Read Interrupt Mask) instruction in the 8085 microprocessor, explaining its role in managing interrupts. RIM disables specific interrupts by reading their status, represented by bits in the accumulator. The video clarifies the function of each bit, including the interrupt enable (IE), pending interrupts (RST 7.5, RST 6.5, RST 5.5), and the serial input data (SID). It emphasizes the importance of understanding which interrupts are enabled, pending, or masked for effective microprocessor operation. Stay tuned for the next video on the SIM (Set Interrupt Mask) instruction.
Takeaways
- 📘 The full form of RIM is 'Read Interrupt Mask', which is used to disable interrupts.
- 😷 Masking interrupts is akin to wearing a face mask, covering them to prevent their effect.
- 🔢 The RIM instruction reads the status of three interrupts: RST 7.5, RST 6.5, and RST 5.5.
- 🛑 An interrupt is considered 'masked' or disabled if its corresponding bit in the RIM register is set to 1.
- 👀 The lower order three bits of the RIM register represent the status of the interrupts.
- 💡 The IE (Interrupt Enable) bit, located at D3, controls whether interrupts are enabled or disabled.
- 🚨 The three bits at D4, D5, and D6 represent the pending status of the RST 7.5, RST 6.5, and RST 5.5 interrupts, respectively.
- 🔝 The most significant bit, D7, represents the Serial Input Data (SID).
- 🔄 After executing the RIM instruction, the status of interrupts and SID is loaded into the accumulator.
- 📊 The accumulator can then be used to determine which interrupts are pending, enabled, or masked.
- 👋 The next tutorial will cover the SIM (Set Interrupt Mask) instruction, which is used to set which interrupts are masked.
Q & A
What does RIM stand for in the context of microprocessors?
-RIM stands for Read Interrupt Mask. It is an instruction that reads the status of interrupts in a microprocessor.
What is the purpose of the RIM instruction in microprocessors?
-The RIM instruction is used to read the status of various interrupts, such as whether they are enabled, masked, or pending, and the serial input data.
How does the RIM instruction relate to interrupt handling in microprocessors?
-The RIM instruction helps in understanding which interrupts are enabled, which are masked (disabled), and which are pending, allowing for proper interrupt handling.
What does the term 'masking' mean in the context of interrupts?
-Masking interrupts means disabling them. In the context of the RIM instruction, if an interrupt is masked, it will not be processed.
What are the three interrupts mentioned in the script, and how are they represented in the RIM instruction?
-The three interrupts mentioned are RST 7.5, RST 6.5, and RST 5.5. They are represented by the lower order three bits of the data read by the RIM instruction.
How can you determine if an interrupt is enabled or disabled using the RIM instruction?
-By examining the accumulator after executing the RIM instruction, if the bit corresponding to an interrupt is 1, it means the interrupt is masked (disabled). If it is 0, the interrupt is enabled.
What does the IE bit represent in the RIM instruction, and how does it affect interrupt processing?
-The IE bit, represented by D3 in the accumulator, stands for Interrupt Enable. If IE is set to 1, interrupts will be enabled for processing; if it is 0, they are disabled.
What does it mean for an interrupt to be 'pending'?
-An interrupt is considered 'pending' if it has occurred but has not yet been acknowledged or processed by the microprocessor.
How is the status of pending interrupts represented in the accumulator after the RIM instruction?
-The status of pending interrupts is represented by bits in the accumulator. If a bit corresponding to an interrupt is set to 1, it indicates that the interrupt is pending.
What is the significance of the most significant bit (D7) in the accumulator after executing the RIM instruction?
-The most significant bit (D7) represents the Serial Input Data (SID). It reflects the serial input data after the RIM instruction is executed.
What is the SIM instruction mentioned at the end of the script, and how does it differ from the RIM instruction?
-The SIM instruction stands for Set Interrupt Mask. It is used to set or mask interrupts, whereas the RIM instruction is used to read the status of interrupts and serial input data.
Outlines
📘 Understanding the RIM Instruction
The first paragraph introduces the RIM (Read Interrupt Mask) instruction in the microprocessor tutorial series. It explains the full form of RIM as 'Read Interrupt Mask', emphasizing its function to disable interrupts. The tutorial discusses how RIM can be used to determine the status of three interrupts (RST 7.5, RST 6.5, and RST 5.5) by examining specific bits in an 8-bit data format. The paragraph also explains the concept of masking interrupts and how the RIM instruction helps in identifying whether interrupts are enabled or disabled, pending, or acknowledged. It touches on the significance of the IE (Interrupt Enable) bit and the role of the most significant bit (D7) as the Serial Input Data (SID). The summary concludes with the practical application of the RIM instruction, which is to load the status of interrupts and serial data input into the accumulator for further analysis.
🔍 Analyzing the RIM Instruction's Output
The second paragraph delves deeper into the RIM instruction's output, explaining how it provides insights into the status of interrupts and the serial data input. It clarifies that the RIM instruction loads the pending interrupts, interrupt masks, and the state of the serial input data into the accumulator. The paragraph illustrates how to interpret the accumulator's data to understand which interrupts are pending, enabled, or maxed (disabled). It also explains the significance of the least significant bit in determining which interrupt is maxed. The summary ends with an overview of the RIM instruction's purpose in the context of the 8085 microprocessor and teases the upcoming SIM (Set Interrupt Mask) instruction in the next video. The paragraph concludes with an invitation for viewers to ask questions, like, share, and subscribe to the channel.
Mindmap
Keywords
💡Microprocessor
💡RIM (Read Interrupt Mask)
💡Interrupt
💡Masking
💡Accumulator
💡IE (Interrupt Enable)
💡Pending Interrupt
💡Serial Input Data (SID)
💡Instruction Set
💡SIM (Set Interrupt Mask)
Highlights
Introduction to the microprocessor tutorial series.
Explanation of the RIM (Read Interrupt Mask) instruction.
RIM stands for Read Interrupt Mask, which is used to disable interrupts.
The concept of masking interrupts is compared to wearing a face mask.
Description of the three interrupts: RST 7.5, RST 6.5, and RST 5.5.
Explanation of how the RIM instruction reads the status of interrupts.
Details on how the lower order three bits represent the mask interrupts.
The function of the IE (Interrupt Enable) bit and its role in enabling interrupts.
Clarification of the meaning of pending interrupts and their representation by bits.
The significance of the most significant bit (D7) as the Serial Input Data (SID).
How the RIM instruction loads the status of interrupts and SID into the accumulator.
Understanding which interrupts are pending, enabled, or masked after the RIM instruction.
The practical application of the RIM instruction in microprocessor programming.
Upcoming tutorial on the SIM (Set Interrupt Mask) instruction.
Invitation for viewers to ask questions in the comment section.
Encouragement for viewers to like, share, and subscribe to the channel.
Transcripts
dear students i welcome you all to this
microprocessor tutorial series in this
video we will learn about the rim
instruction and in our upcoming video we
will learn about the sim instruction so
what is the full form of rhythm rim
stands for read interrupt max that means
whatever be the interrupt that is maxed
max meanings it is disabled so let me
write down here
masking means it is disabling disabling
means we are just covering something
suppose we are wearing a face mask that
means we are covering our face another
person are not able to see our face in
the case of microprocessor also when you
max some interrupts that means that
interrupt will be disabled using this
read interrupt marks we will know the
various status of the interrupts so here
we will see basically three interrupts
that is the rst 7.5 rsd 6.5 and rsd 5.5
here i have shown a 8 bit data suppose
from d 0
d 1 d 2
d 3 d 4
d5 d6 d7 so in the case of read
interrupt marks what will happen the
lower order three bits here these three
bits this one three these three bits
this will be having the
max interrupts so let me write down
first this is
7.5 this is 6.5 and this is for 5.5 this
is the rst 7.5 rsd 6.5 and rst 5.5 so
these are the marks interrupts okay so
let me write down here this is the marks
of
interrupts so when this interrupt will
be marked that will be dependent on
these bits so if this value is 1
if equal to 1
that means this is interrupt is mass
must means it is disabled that means
whenever we have suppose 1 0 0 that
means rst 7.5 is disabled other are
enabled so whenever we have one value
here that will represent that that
interrupt is maxed max means it is
disabled okay next we have the ie here
ie means let me write down here d3 bit
will represent the ie ie means interrupt
enable so what will be the function if
this is equal if this interrupt enable
equal to 1 whatever be the interrupt
here depending on the max that interrupt
will be functioning and if this equal to
0 then this is disabled 0 means disable
1 means enable at this interrupt enable
bit so this is the third bit okay next
we have d4 at d4 will be having a
interrupt
six enter 5.5 here i'll be having
interrupt
6.5 and
i
7.5 so what is the meaning of this three
interrupt whenever we have one value in
any of these interrupts suppose in some
cases all of this inter may be having
one value all of these bits having one
value that means the interrupt is
pending
if let me write down here if these
values equal to 1 that means that
interrupt is equal to pending that means
interrupt is not acknowledged this is
the meaning of these three bits and the
most significant bit that is d7 it will
represents as i d it will represent s id
s id means it is the serial input data
so whatever be the data that is serial
input that will be reflected here after
going through this instruction all the
status values suppose it may be having
0 0 1 0 1 0 0 1 suppose this is the
content of this interrupt status signals
so after going through this instruction
this data will be written into the
accumulator so after having the bits in
the accumulator then we can easily
understand which interrupt is pending
which interrupt is enabled or not if
there is a max interrupt or not so from
that we can easily understand so suppose
for this example only let me tell you
this most significant bit this will
represent the s id as id means it is the
serially input data so you need not to
bother about this next we have this one
is the distribution represents the
interrupt which is pending that means
this one was for the rst 7.5 this one is
for rst 6.5 this is for rst 5.5 so what
we understand from here that r s t the
second one this one rsv this one is
pending because this value this bit is
one therefore we can write rsd 6.5 is
pending so after reading the interrupt
status we can understand that the
restart or the rsd 7.5
interrupt is pending next we have this
one value one value means it is the
interrupt enable signal so if value if
this value is one that means interrupt
is enable that means it is interrupt is
enabled next we have these are the three
bits this three bit will represent which
interrupt is maxed so from here we can
say that the interrupt 5.5 is
maxed
why i'm writing here five point five
because the least significant bit is one
here if this one was one then what will
happen the interrupt six point five is
max if this value has been one then we
could have said that the interrupt 7.5
is maxed so in this way you have to
understand that in the case of rim
instruction what will happen this rim
instruction is used to read the status
of the interrupts that is 7.5 6.5 and
5.5 and the serial data input bits okay
so we have seen about this rim
instruction this instruction loads the
pending interrupts as well as the
interrupt marks as well as the restart
inter marks and the contents of the
serial input data into the accumulator
so after going through this instruction
this data will be written into the
accumulator okay this is all about the
rim instruction in 8085 in our upcoming
video we will see about the sim
instruction that is the set interrupt
max instruction thank you for watching
if you have any question please put it
in the comment section below also like
share and subscribe to my channel thank
you
[Music]
you
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