List of Most Frequently Asked Computer Architecture Interview Questions And Answers to Help You Prepare For The Upcoming Interview:
Are you an aspirant preparing for a Computer Architecture interview? Do you aspire to shine in this field and become an expert? Are you planning to master your skills in Computer Architecture? Worry not, as you are at the right place now!
Computer Architecture has gained tremendous importance in this digital era. The implementation, functionality, and organization of any system of computer are explained in detail with many sets of rules and methods.
As it is done through the key implementation of Computer Architecture, it is considered as one of the main subjects that students have to grasp in computer engineering.
The unique definition of every architecture defines the computer’s capabilities and programming models related to it. However, it doesn’t define the implementation.
If you are seeking a Computer Architecture job, then you must be well-versed with the computer architecture interview questions. The interview question varies with different job profiles. Here are a few questions that will help you to prepare for the interview and pass it with flying colors.
Table of Contents:
List Of The Top Computer Architecture Interview Questions
Basic Interview Questions
Q #1) What do you understand by the term Computer Architecture?
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Suggested Reading =>> What Is A Microprocessor – Complete Guide With Examples
Answer: Computer Architecture is the detailed specification about how a set of standards related to hardware and software interact with each other to create a computer system or a platform.
Concisely, it refers to the designing of a computer system and its compatibility with the technologies. It is like the art of determining what the user, technology and the system need and then creating logical standards and designs based on the above needs.
Q #2) Is Computer Architecture different from a Computer Organization?
Answer:
| Computer Architecture | Computer Organisation |
|---|---|
| It is the way hardware is connected to create a computer system. | It is the computer’s design and the behavior as perceived by the user. |
| Computer architecture is the connection between software and hardware. | In a system, it handles a component’s connection. |
| It makes understanding of the system’s functions easy. | It maps all the units in a system, their interconnection, and arrangement. |
| Registers, instructions, and addressing modes are parts of the architecture. | The realization of computer architecture is the organization. |
| Architecture comes first in computer system design. | The base of an organization is architecture. |
| Deals with high-level issues of designs. | Deals with low-level issues of design. |
| Involves Logic. | It involves physical components. |
Q #3) Do you know the basic components used by a Microprocessor? Explain.
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Answer:
Microprocessor normally uses three basic components:
- Address lines are one of the major elements of a Microprocessor as it is important for referring to the proper address of a single block.
- Data lines are the elements that maintain the main criteria for transferring data for a microprocessor.
- The target of the processing data comes after the completion of addressing and data transfer. IC chips are vital for data processing in a microchip.
Q #4) What are the various Interrupts in a Microprocessor system?
Answer:
There are three types of interrupts:
- External interrupts that come from external input/output devices.
- Internal interrupts are the result of any exception caused by the program itself.
- Software interrupts occur only during the execution of an instruction. The main aim of such interrupts is to switch modes from the user to the supervisor.
Q #5) What are the common Components of a Microprocessor?
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Answer: Control units, I/O units, Cache, ALU, and Registers are some of the common components of a Microprocessor.
Technical Questions
Q #6) What do you know about MESI?
Answer: MESI is one of the extremely popular cache coherence protocols based on Invalidate that support write-back caches. As it was developed at the University of Illinois at Urbana-Champaign, it is also named as the Illinois protocol.
Initially, the write-through cache that caused the loss of huge bandwidth was used. Write back cache became popular as they efficiently and properly manage the bandwidth in the system. MESI protocol maintains one stage called the dirty stage that indicates the system that the data in this cache is different from the stored data in the main memory’s cache.
Q #7) Are you aware of Pipelining?
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Answer: Pipelining is one of the most popular techniques used by an advanced microprocessor that is mainly used when multiple instructions enter into the system. It accumulates instruction from the processor via a pipeline and allows storing and execution of instructions in an orderly process.
The process is divided into stages and each of them is connected in a pipe-like structure. It is used where multiple instructions are overlapped during execution.
Like in a car manufacturing company, each setup of huge assembly lines, and robotic arms perform certain tasks. After one task is completed, the car moves on ahead to the next arm.
Q #8) What do you know about Cache Coherence?
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Answer: The consistency or regularity of data stored in the cache memory is called cache coherence. It is imperative for Distributed Shared Memory (DSM) or multiprocessor systems to maintain cache and memory consistency.
Cache management is structured to see that the data is not lost or overwritten. You can use different techniques to maintain cache coherency, and that includes snarfing, snooping and directory-based coherence.
A DSM system uses a coherency protocol by imitating these techniques for maintaining consistency and it is essential to system operations. Cache coherence requires two things i.e. write propagation and transaction serialization.
In any cache, the changes to the data must be disseminated to other copies of that cache line in the peer caches. This is what the write propagation does. The job of transaction serialization is to make sure that anything which is read or written to a single memory location is seen by all the processors in the same order.
Q #9) Tell us about the Cache miss.
Answer: Sometimes, there is a failed attempt to write or read a part of the data in the cache. This miss results in longer latency in the main memory. There are three types of cache miss i.e. cold or compulsory, capacity and conflict miss.
Cold or compulsory miss starts with an empty cache and is the foremost reference to a memory block. You can refer to it as an empty hotel where the first guest hasn’t arrived yet. A capacity miss occurs when the cache doesn’t have enough space to hold all the blocks that you want to use. It is like a hotel where you want to stay but has no vacancy.
Conflict miss happens when the same location gets two blocks but doesn’t have enough space for both of them. In an easy example, it is like you are supposed to stay on the third floor of a hotel but all the rooms on the floor are occupied and there is no room for you.
Q #10) What do you know about Virtual Memory?
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Answer: Your computer uses memory to load the OS & run the programs and the amount of real memory, i.e. RAM, is finite. Thus, there are chances for you to run out of memory, especially when you are running too many programs at one time.
That’s where virtual memory comes in handy. It increases the memory available in your computer by enlarging the “address space” i.e. places in memory where you can store data. It uses the hard disk space for allocating additional memory.
However, the hard drive is slower when compared to RAM, thus, you must map the data stored in virtual memory back to the real memory to be used. Virtual memory enables your computer to run more programs than it can.
Q #11) What are the 5 stages of the DLX pipeline?
Answer: DLX is a RISC processor architecture. It was designed by David A. Patterson and John L. Hennessy. Its architecture was chosen based on the observations of the most frequently used primitives in programs.
Its 5 stages include:
- CPU Operand Storage
- Explicit operands
- Operation
- Location
- Type and size of operands
Q #12) Tell us about Superscalar machines and VLIW machines.
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Answers: Superscalar processor is a CPU that implements instruction-level parallelism within a single processor. It can execute more than one instruction during a clock cycle. It simultaneously dispatches multiple instructions to different execution units on the processor.
Thus, it allows for more throughput when compared to others to be possible at a given clock rate.
VLIW or Very Long Instruction Word refers to a CPU architecture that is designed to take advantage of ILP or instruction-level parallelism but with minimum hardware complexities. The VLIW approach executes the operation in parallel which is based on a fixed schedule that is determined when programs are compiled.
Q #13) What is Branch Prediction and how can it control Hazards?
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Answer: In a unit of information processing that processes a pipeline, a branch prediction control device generates an address for branch prediction. This address is used to verify the instructions that are being executed speculatively.
The device has a first return address storage unit that stores the return address for prediction. Then, there is a storage unit for the second return address that stores a return address that is generated based on the result of an execution of the call instruction.
There is also a storage unit for a branch prediction address that sends a stored prediction return address as a branch prediction address and stores the branch prediction addresses that are sent.
When the return address is generated after the execution of a branch instruction that differs from the branch prediction address, then the contents that are stored in the storage unit for the second return address are duplicated to the storage unit for the first return address.
Q #14) Can you calculate the number of sets given with its size and way in a cache?
Answers: In the hierarchy of primary storage, a cache carries cache lines collected into sets. The cache can be called k-way associative if each set holds k lines. A data request possesses an address that specifies the position of the data requested.
You can place only one cache-line data of the size of the chunk from the lower level into one set. Its address decides the set in which it can be placed. The mapping between the sets and addresses must have a fast and easy implementation. For fast implementation, only a part of the address chooses the set.
After that, a request address is separated into three fragments as shown below:
- A specific position within a cache line is identified by an offset part.
- The set that has the requested data is identified by a set part.
- There must be a saved tag part along with its data in each cache line to distinguish the different addresses that could be put in the set.
Q #15) How do you find a Block in a Cache?
Answer: Block’s tag is recorded by each place in the cache along with its data. The place in the cache might be unoccupied, so it usually maintains a valid bit.
Thus, to find the block in cache:
- Determine the place or set of places used in the index of block address.
- Check if a valid bit is set for each place and compare the tag with that address block parallelly for all places in a set.
Q #16) What is an Addressing Mode?
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Answer: In the most central processing unit designs, there is a characteristic of the instruction set architecture called addressing modes.
The diverse addressing modes are explained in a given instruction set architecture and these modes define how ML instructions in the given architecture recognize the operands of every instruction.
Addressing modes specify the way to compute the effectual memory address of an operand with the use of the information kept in registers or/and constants held within an ML instruction or somewhere else.
Q #17) Tell us about Aliasing.
Answer: Aliasing, in the world of computing, describes a circumstance where you can access the location of data in memory through separate symbolic names in the program. Thus, by changing the data through one name, you can implicitly modify the values correlated with every aliased name.
That’s something the programmer might not have anticipated. Hence, the programs become difficult to optimize, understand and analyze.
Q #18) What is the difference between Software and Hardware interrupts?
Answer:
| Software Interrupts | Hardware Interrupts |
|---|---|
| These can be invoked with the help of INT instruction. | These are caused by external devices, especially hardware failure. |
| It is synchronous. | It is asynchronous. |
| It is caused by any internal system of the computer. | It happens when the signal for the processor is from an external device or hardware. |
| This is often the result of either an exceptional condition in the processor or special instruction in the instruction set. | It is the result of outside interference, be it from peripherals, users, through a network, or other hardware devices. |
| PC incremented. | PC isn’t incremented. |
| It has the highest priority. | It has the lowest priority. |
Q #19) You want to do other tasks but the CPU is busy. Suggest a solution.
Answer: I will create an interrupt that is non-maskable and then give the jump instruction to the essential subroutine.
Q #20) What do you know about Latches? What are the various types of Latches?
Answer: Latch, also known as a bistable-multivibrator due to its two stable states of active high and active low, is a type of logic circuit. Through a feedback lane, it holds the data, thereby acting as a storage device.
As long as the apparatus stays active, the latch can store a 1-bit of data. The latch can instantly change the data stored once enable is declared.
Types of Latches:
- SR or set/reset latch, the asynchronous apparatus, works independently to control signals. It is done depending on the set-state and reset-input.
- Gates SR Latch is the latch that carries the third input. This input must be active for set/reset inputs to work.
- D latch or the data latch removes the chance of undesirable conditions of input.
- Gated D latch is designed by making some changes in the gated SR latch. The change made is that the reset input must be changed to the inverter set.
- JK latch is similar to RS latch. It comprises two inputs i.e. J and K. When the inputs of JK latch are high, the output is bound to toggle.
- T latch is formed when the inputs of JK latch are shorted. T latch toggles the output when the latch’s input is high.
Q #21) Tell us something about Flip Flops.
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Answer: Just like latch, a flip flop is an electronic circuit. It carries two stable states that can store binary data. By applying various inputs, you can change the stored data. Like latches, it is the building block of electronic and digital systems of computers, in communication and many other systems.
Q #22) Explain the differences between Latches and Flip-flops.
Answer:
| Latches | Flip-Flops |
|---|---|
| These building blocks can be built from logic gates. | While latches are used to build these building blocks. |
| It checks the inputs continuously and changes the output accordingly. | Flip-flop does the same thing but only at the time set by the clocking signal. |
| Latches are sensitive to the pulse duration and when the switch is turned on, it can receive and send the data. | It is sensitive to the change in the signal. The transfer of data can take place only at a single instant. You can’t change the data until the signal changes next. These are used as registers. |
| Enable function input is what it works on. | It works on clock pulses. |
Q #23) What do you know about the Real-time Operating System?
Answer: Also known as a data processing system, the real-time operating system requires an extremely small time interval for processing and responding to the inputs. The time it takes to respond and display the required updated information is called response time.
We use real-time when the time requirements for operating a processor or for the flow of data are rigid. In a dedicated application, we can use the real-time system as a control device. This system must have definitive and fixed time constraints, else it will feel.
Q #24) Difference between Write-back and Write-through Cache.
Answer:
| Write Back Cache | Write Through Cache |
|---|---|
| Write back cache differs the write until that cache line has been used for read. This, in turn, puts a question mark on its integrity, especially when many processors access the same data employing its internal cache. | The write through caches flushes for each writes hence is considered better in integrity. |
| It saves many write or memory write cycle, hence giving a good performance. | Compared to write back cache, it doesn’t give such a good performance. |
Q#25) Why should we hire you?
Answer: In the answer to this question, tell them how dedicated you are to your work. Talk about how you have learned new things during your career and how well you have learned from your mistakes. Put forward an example where you performed exceptionally well.
Give them a picture of the kind of employee that they are looking for.
Conclusion
These are some of the most popular Computer Architecture interview questions. Being prepared with the frequently asked questions will increase your chances of clearing the interview.
Your knowledge of the subject will not only help you to be confident in your interview but also ace it with the exact answers.
We hope that this list of Computer Architecture Interview Questions was helpful to you!!