coa viva question 2

 1) Explain what is Computer Architecture?

Computer architecture is a specification detailing about how a set of software and hardware standards interacts with each other to form a computer system or platform.

2) How Computer Architecture is characterized?

The computer architecture is characterized into three categories

• System Design: It includes all the hardware component in the system, including data processor aside from the CPU like direct memory access and graphic processing unit
• Instruction Set Architecture (ISA): It is the embedded programming language of the central processing unit. It determines the CPU’s functions and capabilities based on programming it can process.
• Microarchitecture: It defines the data path, storage element, and data processing as well as how they should be implemented in the ISA.

3) Mention important steps for computer design?

A CPU architecture is defined by the set of machine language which can be defined as a

• Set of registers and their functions ( capabilities )
• Sequence of micro-operations performed on the data stored in registers
• Control signals that initiate the sequence

4) Mention what are the different types of fields that are part of an instruction?

The different types of fields that are parts of an instruction are

• Operation Code Field or OP Code field: This field is used to determine the operation to be performed for the instruction
• Address Field: This field is used to determine various addresses such as memory address and register address
• Mode Field: This field determines how operand is to perform or how effective address is derived

5) Mention what are the basic components of a Microprocessor?

The basic components of a Microprocessor are

• Address lines to refer to the address of a block
• Data lines for data transfer
• IC chips for processing data

6) Mention what are different types of interrupts in a microprocessor system? Explain?

There are three types of interrupts that can cause a break.

• External Interrrupts:

From external input/output devices such types of interrupt comes.

• Internal Interrupts:

These types of interrupts are caused due to any exception caused by the program itself. For example, division by zero or an invalid opcode, etc.

• Software Interrupts:

Only during the execution of an instruction such type of interruption can occur.  The primary purpose of such interrupts is to switch from user mode to supervisor mode.

7) Mention what are the common components of a microprocessor are?

The common components of a microprocessor include

• I/O Units
• Control Unit
• Arithmetic Logic Unit (ALU)
• Registers
• Cache

8) Explain what is Snooping Cache?

Snooping Cache is the process where individual caches monitor address lines for accesses to memory locations that they have cached.

9) Mention what is the simplest way to determine cache locations in which to store memory blocks?

Direct Mapping is the simplest way to define cache locations in which to store memory blocks. Associative memories are expensive in comparison to random-access memories due to the added logic associated with each cell.

10) What digital functions should be used to convert the octal code to binary code?

To convert the octal code to binary code multiplexers is used. It is also referred as Data Selector, where dynamic memory uses the same address lines for both row and column.

11) What technique is used to automatically move program and data blocks into the physical main memory when they are required for execution?

Virtual Memory technique is used. It provides a mechanism for translating program generated address into correct main memory locations.  By means of mapping table translation or mapping is handled.

12) Mention what is the use of RAID system?

The use of RAID system is to increase the disk storage capacity and availability.

13) Explain what type of memory that can be erased with the electric discharge?

With the passage of electric discharge, EEPROM is the type of memory whose content is erased.

14) Explain what is horizontal micro code?

The horizontal micro code contains the control signal without any intermediary.  It contains a lot of signals and hence due to that the number of bits also increases.

15) Explain what is direct mapping?

In direct mapping, the RAM is used to store data and some of the data is stored in the Cache.  The address space is divided into two parts index field and tag field.  The tag field is used to store the tag field whereas the rest is stored in the main memory.

16) Mention what are the types of micro-operations?

The types of micro-operations are

• Register transfer micro-operations: These type of micro-operations are used to transfer information from one register to another binary information
• Shift micro-operation: These operations are used to perform shift operations in data store in registers
• Logic micro-operation: These are used to perform on numeric data stored in the registers some arithmetic operations
• Arithmetic micro-operations: These micro-operations are used to execute some arithmetic operations on numeric data stored in the registers

17) What does DMA stands for?

DMA stands for Direct Memory Access.

18) When large number of registers are included in the CPU, what is the most efficient way to connect them?

When large number of registers are included in the CPU, the most efficient way to connect them is through an ALU.

19) Explain if the internal bus connects only register within the CPU, how would you get data to and from memory?

The AR or Address Register is used to select a memory address, and the Data Register is used to send and receive the data.  Both these register are connected to the internal BUS, and the Data Register acts as a bridge between the memory data BUS and internal BUS.

So first we load AR with the desired memory address and then transfer to or from Data Register.

20) Explain what is WAIT state?

A WAIT state plays a key role in preventing CPU speed incompatibilities.  Many times the processor is at ready state to accept data from a device or location, but there might be no input available. In such case there will be wastage of CPU time, and the system gets into WAIT state.

21) Explain how you can deal with WAIT state?

The one way to deal with WAIT state is increasing the microprocessor clock period by reducing the clock frequency

The second way is by using special control input READY. It allows the memory to set its own memory cycle time.

22. What is computer architecture?

Example: "Computer architecture refers to hardware instructions, software standards and technology infrastructure that define how computer platforms, systems and programs operate. This means that computer architecture outlines the system's functionality, design and compatibility."

23. What are the three categories of computer architecture?

Example: "Computer architecture has three categories. These include:

System design

This includes all the hardware components in the system such as the data processors, direct memory access and graphics processing unit. It also includes data paths, memory controllers and miscellaneous things such as virtualization and multiprocessing.

Instruction Set Architecture

This is a part of the central processing unit that is visible to the compiler writer and programmer. It defines the CPU's capabilities and functions based on what programming it can process and perform. This includes the data formats, memory addressing modes, processor register types, word size and the instruction set that programmers use.

Microarchitecture

Also known as "computer organization," this kind of architecture defines storage elements, data processing and data paths, as well as how they should be implemented in the ISA."

24. What are some of the components of a microprocessor?

Example: "Some of the components of a microprocessor include the arithmetic and logic unit, which performs math computations such as division, addition and subtraction and Boolean functions; registers, which act as the temporary data holding places of microprocessors; control units, which receive signals from the CPU and move data from one microprocessor to another; and memory caches, which accelerate the computing process, as the CPU doesn't have to use the slower RAM to retrieve data."

25. What is MESI?

Example: "MESI stands for the four states of the cache blocks, which are Modified, Exclusive, Shared and Invalid. It's also known as the "Illinois protocol". It's used to maintain cache coherency in hierarchical memory systems. MESI is the most common protocol that supports write-back cache. Its use in personal computers became common with the introduction of Intel's Pentium processor."

26. What are the different hazards?

Example: "Hazards have three classes. These include the structural hazards, which occur from resource conflicts when the hardware can't support all possible combinations of instructions in synchronized overlapped execution; data hazards, which occur when instructions that manifest data dependence change data in different stages of a pipeline; and control hazards, which occur from the pipelining of branches and other instructions that modify the PC."

27. What is pipelining?

Example: "Pipelining, also known as "pipeline processing", is the process of collecting instruction from the processor through a pipeline. It stores and executes instructions in an orderly process."

28. What is a cache?

Example: "A cache is a small amount of memory, which is a part of the CPU. It's placed closer to the CPU than the RAM. It temporarily holds data and instructions that the CPU is likely to reuse."

29. What is a snooping protocol?

Example: "A snooping protocol, also referred to as a "bus-snooping protocol," maintains cache coherency in symmetric multiprocessing environments. All caches on the bus snoop or monitor the bus to determine if they have a copy of the block of data that is requested on the bus. Each cache holds a copy of the sharing status of every block of physical memory it has. Typically, several copies of a file in a multiprocessing environment can be read without any problem of coherence. However, a processor should have exclusive access to the bus to write."

30. What are the different types of interrupts in a microprocessor system?

Example: "Interrupts can either be internal or external. Internal interrupts, which are also referred to as "software interrupts", are caused by software instruction and operate similar to a branch or jump instruction. An external interrupt, which is also referred to as a "hardware interrupt," is caused by an external hardware module."

31. What is the easiest way to determine cache locations in which to store memory blocks?

Example: "Direct mapping is the easiest way to define cache locations in which to store memory blocks. It maps each block of the main memory into only one possible cache line. The cache in a direct-mapped cache structure is organized into several sets, with a single line per set. Based on the memory block's address, it can only use a single cache line. The cache can be framed as a column matrix."

32. What is a virtual memory on a computer?

Example: "A virtual memory is an operating systems' memory management feature that uses software and hardware to allow computers to compensate for the shortages of physical memory by temporarily moving data from RAM to disk storage."

33. Can you state some of the common rules of assembly language?

Example: "Some of the common rules of assembly language include the following:

• In assembly language, the label field can either be empty or may define a symbolic address.
• Instruction fields can specify machine pseudo instructions.
• Comment fields can be commented with or left empty.
• In the case of symbolic addresses, up to four characters are only allowed.
• The comment field begins with a forward slash while the symbolic addresses field is terminated by a comma."

34. What is the RAID system?

Example: "RAID, which stands for Redundant Array of Independent Disks, refers to the hard drives connected and set up in ways to help accelerate or protect the performance of a computer's disk storage. It is typically used on servers and high-performance computers."

35. What are the two hardware methods to establish a priority? Explain each method.

Example: "The two different ways to establish hardware priority are the parallel priority and daisy-chaining. Daisy-chaining is a method that involves connecting all the devices that can request an interrupt in a serial manner. This setting is governed by the priority of the devices, in which the device with the highest priority is placed first.

Parallel priority, on the other hand, uses a register for which bits are configured separately by the interrupt signal from each device. It may also come with a mask register, which is used to control the status of each interrupt request."

36. What are flip-flops?

Example: "Flip-flops, also called "latches", are electronic circuits that have two stable states used to store binary data. The data stored in the states can be modified by using varying inputs. Flip-flops are fundamental components of digital electronic systems used in communications, computers and many other kinds of systems."

37. What's the difference between interrupt service routine and subroutine?

Example: "Subroutine is a part of code within a larger program, which performs a specific task and is relatively independent of the remaining code. Interrupt service routines deal with hardware interrupts. They are not independent threads, but more like signals. They are used if an interrupt suspends any thread. Unlike subroutine, which runs when we call it, ISR runs whenever there's a signal from either the software or hardware. The big difference is we can determine where the subroutine runs while we can't determine when the ISR will be executed."

38. What are the different types of fields that are part of instruction?

Example: "An instruction is like a command to a computer to perform a particular operation. The instruction format is composed of various fields in them such as:

• Operation code field. Also called the "op-code field", this field is used to specify the operation to be performed for the instruction.
  
  
  
• Address field. As the term implies, this field is used to designate the various addresses, such as memory address and register address.
  
  
  
• Mode field. This field specifies as to how an operand performs or how effective an address is."

39. What are the steps involved in an instruction cycle?

Example: "A program that resides in the memory contains a set of instructions that the computer needs to perform sequentially. The cycle for every instruction is called the instruction cycle, which consists of the following steps:

• Fetch instruction. The CPU fetches the instruction from the memory. The computer gets loaded with the address of the instruction.
  
  
  
• Decode. This allows the CPU to determine what instruction must be performed and how many operands are needed to fetch to perform an instruction.
  
  
  
• Execute. At this step, the instruction is performed. If the instruction has logic or arithmetic, the ALU is utilized. This is the only step of the instruction cycle that's useful from the end user's perspective."

40. What are the five stages in a DLX pipeline?

Example: "Each DLX instruction has five stages. These include:

1. Instruction fetch
2. Instruction decode and register fetch
3. Execution
4. Memory access
5. Writeback"

41. What are the types of micro-operations?

Example: "Micro-operations are executed on data stored in registers. They are basic math operations performed on the information stored in one or more registers. The types of micro-operations are:

• Shift micro-operations: They perform shift operations on data stored in registers.
  
  
  
• Logic micro-operations: They execute bit manipulation operations on nonnumerical data saved in registers.
  
  
  
• Arithmetic micro-operations: They perform arithmetic operations, such as subtractions and additions, on digital data stored in registers.
  
  
  
• Register transfer micro-operations: They transfer binary information between registers."

42. What is the write-through method?

Example: "Write-through is the preferred method of data storage in many applications, especially in banking and medical device control, as it's good at preventing data loss. In less critical applications, and especially when the volume of data is large, an alternative method known as "write-back" speeds up system performance because updates are typically written exclusively to the cache and are saved in the main memory only under certain conditions or at specified intervals."

43. What is associative mapping?

Example: "The associative mapping technique uses several mapping functions to transfer data from the main memory to the cache memory. This means that any main memory is mapped into any line of the cache. As a result, the cache memory address is not in use. The associative cache controller processes and interprets the request by utilizing the main memory address format."

44. What does wait state mean?

Example: "A wait state means that the computer processor experiences a delay when accessing a device or an external memory that is slow in its response. Wait states are considered wasteful in processor performance, which is why modern-day designs try to either minimize or eliminate wait states. These include pipelines, instruction pre-fetch and pipelines, caches, branch prediction and simultaneous multithreading. While these techniques can't eliminate wait states, they can significantly minimize the problem when they work together."

45. What is DMA?

Example: "DMA, which stands for Direct Memory Access, is a feature of computer systems that allows an input/output device to receive or send data directly from or to the main memory, bypassing the CPU to boost memory operations. The process is performed by a chip known as the DMA controller."

46. What is a horizontal microcode?

Example: "Horizontal microcode, which is usually contained in a fairly wide control store, comes with several discrete micro-operations that are combined into one micro-instruction for simultaneous operation."