Desktop Engineer - IT Interview Questions

Desktop Engineer - IT Interview Questions

1) What is Active Directory?
A central component of the Windows platform, Active Directory directory service provides the means to manage the identities and relationships that make up network environments. For example we can create, manage and administrator users, computers and printers in the network from active directory.

2) What is DNS? Why it is used? What is "forward lookup" and "reverse lookup" in DNS? What are A records and mx records?
DNS is domain naming service and is used for resolving names to IP address and IP addresses to names. The computer understands only numbers while we can easily remember names. So to make it easier for us what we do is we assign names to computers and websites. When we use these names (Like yahoo.com) the computer uses DNS to convert to IP address (number) and it executes our request.

Forward lookup: Converting names to IP address is called forward lookup.

Reverse lookup: Resolving IP address to names is called reverse lookup.

'A' record: Its called host record and it has the mapping of a name to IP address. This is the record in DNS with the help of which DNS can find out the IP address of a name.

'MX' Record: its called mail exchanger record. Its the record needed to locate the mail servers in the network. This record is also found in DNS.

3) What id DHCP? Why it is used? What are scopes and super scopes?

DHCP: Dynamic host configuration protocol. Its used to allocate IP addresses to large number of PCs in a network environment. This makes the IP management very easy.

Scope: Scope contains IP address like subnet mask, gateway IP, DNS server IP and exclusion range which a client can use to communicate with the other PCs in the network.

Superscope: When we combine two or more scopes together its called super scope.

4) What are the types of LAN cables used? What is a cross cable?
Types of LAN cables that are in use are "Cat 5" and "Cat 6". "Cat 5" can support 100 Mbps of speed and "CAT 6" can support 1Gbps of speed.

Cross cable: Its used to connect same type of devices without using a switch/hub so that they can communicate.

5) What is the difference between a normal LAN cable and cross cable? What could be the maximum length of the LAN cable?
The way the paired wires are connected to the connector (RJ45) is different
in cross cable and normal LAN cable.
The theoretical length is 100 meters but after 80 meters you may see drop in speed due to loss of signal.

6) What would you use to connect two computers without using switches?
Cross cable.

7) What is IPCONFIG command? Why it is used?
IPCONFIG command is used to display the IP information assigned to a computer. From the output we can find out the IP address, DNS IP address, gateway IP address assigned to that computer.

8) What is APIPA IP address? Or what IP address is assigned to the computer when the DHCP server is not available?
When DHCP server is not available the Windows client computer assigns an automatic IP address to itself so that it can communicate with the network computers. This ip address is called APIPA. ITs in the range of 169.254.X.X.
APIPA stands for Automatic private IP addressing. Its in the range of 169.254.X.X.

9) What is a DOMAIN? What is the difference between a domain and a workgroup? 
Domain is created when we install Active Directory. It's a security boundary which is used to manage computers inside the boundary. Domain can be used to centrally administrator computers and we can govern them using common policies called group policies.
We can't do the same with workgroup.

10) Do you know how to configure outlook 2000 and outlook 2003 for a user?
Please visit the link below to find out how to configure outlook 2000 and outlook 2003. IT: Help Desk: Quick Guide: Configuring Outlook 2003 for Exchange Server

11) What is a PST file and what is the difference between a PST file and OST file? What file is used by outlook express?
PST file is used to store the mails locally when using outlook 2000 or 2003. OST file is used when we use outlook in cached exchanged mode. Outlook express used odb file.

12) What is BSOD? What do you do when you get blue screen in a computer? How do you troubleshoot it?
BSOD stands for blue screen of Death. when there is a hardware or OS fault due to which the windows OS can run it give a blue screen with a code. Best way to resolve it is to boot the computer is "Last known good configuration".
If this doesn't work than boot the computer in safe mode. If it boots up than the problems with one of the devices or drivers.

13) What is RIS? What is Imaging/ghosting?
RIS stands for remote installation services. You save the installed image on a windows server and then we use RIS to install the configured on in the new hardware. We can use it to deploy both server and client OS. Imaging or ghosting also does the same job of capturing an installed image and then install it on a new hardware when there is a need. We go for RIS or imaging/ghosting because installing OS every time using a CD can be a very time consuming task. So to save that time we can go for RIS/Ghosting/imaging.

14) What is VPN and how to configure it?
VPN stands for Virtual private network. VPN is used to connect to the corporate network to access the resources like mail and files in the LAN. VPN can be configured using the steps mentioned in the KB: How to configure a VPN connection to your corporate network in Windows XP Professional

15) Your computer slowly drops out of network. A reboot of the computer
fixes the problem. What to do to resolve this issue?
Update the network card driver.

16) Your system is infected with Virus? How to recover the data?
Install another system. Install the OS with the lates patches, Antivirus with latest updates. Connect the infected HDD as secondary drive in the system. Once done scan and clean the secondary HDD. Once done copy the files to the new system.

17) How to join a system to the domain? What type of user can add a system to the domain?
Please visit the article below and read "Adding the Workstation to the Domain" http://www.microsoft.com/technet/pro...003/technologi /directory/

18) What is the difference between a switch and a hub?
Switch sends the traffic to the port to which its meant for. Hub sends the traffic to all the ports.

19) What is a router? Why we use it?
Router is a switch which uses routing protocols to process and send the traffic. It also receives the traffic and sends it across but it uses the routing protocols to do so.

20) What are manageable and non manageable switches?
Switches which can be administered are called manageable switches. For example we can create VLAN for on such switch. On no manageable switches we can't do so.

Software Testing Basics - Software Testing Interview Questions and Answers

Software Testing Basics - Software Testing Interview Questions and Answers

1. Can you explain the PDCA cycle and where testing fits in?

Software testing is an important part of the software development process. In normal software development there are four important steps, also referred to, in short, as the PDCA (Plan, Do, Check, Act) cycle.

Let's review the four steps in detail.

Plan: Define the goal and the plan for achieving that goal.

Do/Execute: Depending on the plan strategy decided during the plan stage we do execution accordingly in this phase.

Check: Check/Test to ensure that we are moving according to plan and are getting the desired results.

Act: During the check cycle, if any issues are there, then we take appropriate action accordingly and revise our plan again.

So developers and other stakeholders of the project do the "planning and building," while testers do the check part of the cycle. Therefore, software testing is done in check part of the PDCA cyle.

2. What is the difference between white box, black box, and gray box testing?

Black box testing is a testing strategy based solely on requirements and specifications. Black box testing requires no knowledge of internal paths, structures, or implementation of the software being tested.

White box testing is a testing strategy based on internal paths, code structures, and implementation of the software being tested. White box testing generally requires detailed programming skills.

There is one more type of testing called gray box testing. In this we look into the "box" being tested just long enough to understand how it has been implemented. Then we close up the box and use our knowledge to choose more effective black box tests.
The above figure shows how both types of testers view an accounting application during testing. Black box testers view the basic accounting application. While during white box testing the tester knows the internal structure of the application. In most scenarios white box testing is done by developers as they know the internals of the application. In black box testing we check the overall functionality of the application while in white box testing we do code reviews, view the architecture, remove bad code practices, and do component level testing.

3. Can you explain usability testing?

Usability testing is a testing methodology where the end customer is asked to use the software to see if the product is easy to use, to see the customer's perception and task time. The best way to finalize the customer point of view for usability is by using prototype or mock-up software during the initial stages. By giving the customer the prototype before the development start-up we confirm that we are not missing anything from the user point of view.

4. What are the categories of defects?

There are three main categories of defects:

Wrong: The requirements have been implemented incorrectly. This defect is a variance from the given specification.

Missing: There was a requirement given by the customer and it was not done. This is a variance from the specifications, an indication that a specification was not implemented, or a requirement of the customer was not noted properly.

Extra: A requirement incorporated into the product that was not given by the end customer. This is always a variance from the specification, but may be an attribute desired by the user of the product. However, it is considered a defect because it's a variance from the existing requirements.

5. How do you define a testing policy?

The following are the important steps used to define a testing policy in general. But it can change according to your organization. Let's discuss in detail the steps of implementing a testing policy in an organization.

Definition: The first step any organization needs to do is define one unique definition for testing within the organization so that everyone is of the same mindset.

How to achieve: How are we going to achieve our objective? Is there going to be a testing committee, will there be compulsory test plans which need to be executed, etc?.

Evaluate: After testing is implemented in a project how do we evaluate it? Are we going to derive metrics of defects per phase, per programmer, etc. Finally, it's important to let everyone know how testing has added value to the project?.

Standards: Finally, what are the standards we want to achieve by testing? For instance, we can say that more than 20 defects per KLOC will be considered below standard and code review should be done for it.

6. On what basis is the acceptance plan prepared?

In any project the acceptance document is normally prepared using the following inputs. This can vary from company to company and from project to project.

Requirement document: This document specifies what exactly is needed in the project from the customers perspective.

Input from customer: This can be discussions, informal talks, emails, etc.

Project plan: The project plan prepared by the project manager also serves as good input to finalize your acceptance test.

 7. What is configuration management?

Configuration management is the detailed recording and updating of information for hardware and software components. When we say components we not only mean source code. It can be tracking of changes for software documents such as requirement, design, test cases, etc.

When changes are done in adhoc and in an uncontrolled manner chaotic situations can arise and more defects injected. So whenever changes are done it should be done in a controlled fashion and with proper versioning. At any moment of time we should be able to revert back to the old version. The main intention of configuration management is to track our changes if we have issues with the current system. Configuration management is done using baselines.

8. How does a coverage tool work?

While doing testing on the actual product, the code coverage testing tool is run simultaneously. While the testing is going on, the code coverage tool monitors the executed statements of the source code. When the final testing is completed we get a complete report of the pending statements and also get the coverage percentage.

9. Which is the best testing model?

In real projects, tailored models are proven to be the best, because they share features from The Waterfall, Iterative, Evolutionary models, etc., and can fit into real life time projects. Tailored models are most productive and beneficial for many organizations. If it's a pure testing project, then the V model is the best.

10. What is the difference between a defect and a failure?

When a defect reaches the end customer it is called a failure and if the defect is detected internally and resolved it's called a defect.

11. Should testing be done only after the build and execution phases are complete?

In traditional testing methodology testing is always done after the build and execution phases.

But that's a wrong way of thinking because the earlier we catch a defect, the more cost effective it is. For instance, fixing a defect in maintenance is ten times more costly than fixing it during execution.

In the requirement phase we can verify if the requirements are met according to the customer needs. During design we can check whether the design document covers all the requirements. In this stage we can also generate rough functional data. We can also review the design document from the architecture and the correctness perspectives. In the build and execution phase we can execute unit test cases and generate structural and functional data. And finally comes the testing phase done in the traditional way. i.e., run the system test cases and see if the system works according to the requirements. During installation we need to see if the system is compatible with the software. Finally, during the maintenance phase when any fixes are made we can retest the fixes and follow the regression testing.

Therefore, Testing should occur in conjunction with each phase of the software development.

12. Are there more defects in the design phase or in the coding phase?

The design phase is more error prone than the execution phase. One of the most frequent defects which occur during design is that the product does not cover the complete requirements of the customer. Second is wrong or bad architecture and technical decisions make the next phase, execution, more prone to defects. Because the design phase drives the execution phase it's the most critical phase to test. The testing of the design phase can be done by good review. On average, 60% of defects occur during design and 40% during the execution phase.

  

13. What group of teams can do software testing?

When it comes to testing everyone in the world can be involved right from the developer to the project manager to the customer. But below are different types of team groups which can be present in a project.

Isolated test team

Outsource - we can hire external testing resources and do testing for our project.

Inside test team

Developers as testers

QA/QC team.

14. What impact ratings have you used in your projects?

Normally, the impact ratings for defects are classified into three types:

Minor: Very low impact but does not affect operations on a large scale.

Major: Affects operations on a very large scale.

Critical: Brings the system to a halt and stops the show.

15. Does an increase in testing always improve the project?

No an increase in testing does not always mean improvement of the product, company, or project. In real test scenarios only 20% of test plans are critical from a business angle. Running those critical test plans will assure that the testing is properly done. The following graph explains the impact of under testing and over testing. If you under test a system the number of defects will increase, but if you over test a system your cost of testing will increase. Even if your defects come down your cost of testing has gone up.

16. What's the relationship between environment reality and test phases?

Environment reality becomes more important as test phases start moving ahead. For instance, during unit testing you need the environment to be partly real, but at the acceptance phase you should have a 100% real environment, or we can say it should be the actual real environment. The following graph shows how with every phase the environment reality should also increase and finally during acceptance it should be 100% real.

17. What are different types of verifications?

Verification is static type of s/w testing. It means code is not executed. The product is evaluated by going through the code. Types of verification are:

1.         Walkthrough: Walkthroughs are informal, initiated by the author of the s/w product to a colleague for assistance in locating defects or suggestions for improvements. They are usually unplanned. Author explains the product; colleague comes out with observations and author notes down relevant points and takes corrective actions.

2.         Inspection: Inspection is a thorough word-by-word checking of a software product with the intention of Locating defects, Confirming traceability of relevant requirements etc

18. How do test documents in a project span across the software development lifecycle?

The following figure shows pictorially how test documents span across the software development lifecycle. The following discusses the specific testing documents in the lifecycle:

Central/Project test plan: This is the main test plan which outlines the complete test strategy of the software project. This document should be prepared before the start of the project and is used until the end of the software development lifecycle.

Acceptance test plan: This test plan is normally prepared with the end customer. This document commences during the requirement phase and is completed at final delivery.

System test plan: This test plan starts during the design phase and proceeds until the end of the project. 

Integration and unit test plan: Both of these test plans start during the execution phase and continue until the final delivery.

19. Which test cases are written first: white boxes or black boxes?

Normally black box test cases are written first and white box test cases later. In order to write black box test cases we need the requirement document and, design or project plan. All these documents are easily available at the initial start of the project. White box test cases cannot be started in the initial phase of the project because they need more architecture clarity which is not available at the start of the project. So normally white box test cases are written after black box test cases are written.

Black box test cases do not require system understanding but white box testing needs more structural understanding. And structural understanding is clearer i00n the later part of project, i.e., while executing or designing. For black box testing you need to only analyze from the functional perspective which is easily available from a simple requirement document.

20. Explain Unit Testing, Integration Tests, System Testing and Acceptance Testing?

Unit testing - Testing performed on a single, stand-alone module or unit of code.

Integration Tests - Testing performed on groups of modules to ensure that data and control are passed properly between modules.

System testing - Testing a predetermined combination of tests that, when executed successfully meets requirements.

Acceptance testing - Testing to ensure that the system meets the needs of the organization and the end user or customer (i.e., validates that the right system was built).

DBMS Basics - Interview Questions and Answers Part-3

DBMS Basics - Interview Questions and Answers Part-3

42. What is Functional Dependency?

A Functional dependency is denoted by X Y between two sets of attributes X and Y that are subsets of R specifies a constraint on the possible tuple that can form a relation state r of R. The constraint is for any two tuples t1 and t2 in r if t1[X] = t2[X] then they have t1[Y] = t2[Y]. This means the value of X component of a tuple uniquely determines the value of component Y.

43. What is Lossless join property?

It guarantees that the spurious tuple generation does not occur with respect to relation schemas after decomposition.

44. What is 1 NF (Normal Form)?

The domain of attribute must include only atomic (simple, indivisible) values.

45. What is Fully Functional dependency?

It is based on concept of full functional dependency. A functional dependency X Y is full functional dependency if removal of any attribute A from X means that the dependency does not hold any more.

46. What is 2NF?

A relation schema R is in 2NF if it is in 1NF and every non-prime attribute A in R is fully functionally dependent on primary key.

47. What is 3NF?

A relation schema R is in 3NF if it is in 2NF and for every FD X A either of the following is true

1. X is a Super-key of R.
2. A is a prime attribute of R.

In other words, if every non prime attribute is non-transitively dependent on primary key.

48. What is BCNF (Boyce-Codd Normal Form)?

A relation schema R is in BCNF if it is in 3NF and satisfies an additional constraint that for every FD X A, X must be a candidate key.

49. What is 4NF?

A relation schema R is said to be in 4NF if for every Multivalued dependency X Y that holds over R, one of following is true.
1.) X is subset or equal to (or) XY = R.
2.) X is a super key.

50. What is 5NF?

A Relation schema R is said to be 5NF if for every join dependency {R1, R2, ..., Rn} that holds R, one the following is true 1.) Ri = R for some i.
2.) The join dependency is implied by the set of FD, over R in which the left side is key of R.

51. What is Domain-Key Normal Form?

A relation is said to be in DKNF if all constraints and dependencies that should hold on the the constraint can be enforced by simply enforcing the domain constraint and key constraint on the relation.

52. What are partial, alternate,, artificial, compound and natural key?

1. Partial Key: It is a set of attributes that can uniquely identify weak entities and that are related to same owner entity. It is sometime called as Discriminator.
2. Alternate Key: All Candidate Keys excluding the Primary Key are known as Alternate Keys.
3. Artificial Key: If no obvious key, either stand alone or compound is available, then the last resort is to simply create a key, by assigning a unique number to each record or occurrence. Then this is known as developing an artificial key.
4. Compound Key: If no single data element uniquely identifies occurrences within a construct, then combining multiple elements to create a unique identifier for the construct is known as creating a compound key.
5. Natural Key: When one of the data elements stored within a construct is utilized as the primary key, then it is called the natural key.

53. What is indexing and what are the different kinds of indexing?

Indexing is a technique for determining how quickly specific data can be found.
Types:

1. Binary search style indexing
2. B-Tree indexing
3. Inverted list indexing
4. Memory resident table
5. Table indexing

54. What is system catalog or catalog relation? How is better known as?

A RDBMS maintains a description of all the data that it contains, information about every relation and index that it contains. This information is stored in a collection of relations maintained by the system called metadata. It is also called data dictionary.

55. What is meant by query optimization?

The phase that identifies an efficient execution plan for evaluating a query that has the least estimated cost is referred to as query optimization.

56. What is durability in DBMS?

Once the DBMS informs the user that a transaction has successfully completed, its effects should persist even if the system crashes before all its changes are reflected on disk. This property is called durability.

57. What do you mean by atomicity and aggregation?

1. Atomicity: Either all actions are carried out or none are. Users should not have to worry about the effect of incomplete transactions. DBMS ensures this by undoing the actions of incomplete transactions.
2. Aggregation: A concept which is used to model a relationship between a collection of entities and relationships. It is used when we need to express a relationship among relationships.

58. What is a Phantom Deadlock?

In distributed deadlock detection, the delay in propagating local information might cause the deadlock detection algorithms to identify deadlocks that do not really exist. Such situations are called phantom deadlocks and they lead to unnecessary aborts.

59. What is a checkpoint and When does it occur?

A Checkpoint is like a snapshot of the DBMS state. By taking checkpoints, the DBMS can reduce the amount of work to be done during restart in the event of subsequent crashes.

60. What are the different phases of transaction?

Different phases are
1.) Analysis phase,
2.) Redo Phase,
3.) Undo phase.

61. What do you mean by flat file database?

It is a database in which there are no programs or user access languages. It has no cross-file capabilities but is user-friendly and provides user-interface management.

62. What is "transparent DBMS"?

It is one, which keeps its Physical Structure hidden from user.

63. What is a query?

A query with respect to DBMS relates to user commands that are used to interact with a data base. The query language can be classified into data definition language and data manipulation language.

64. What do you mean by Correlated subquery?

Subqueries, or nested queries, are used to bring back a set of rows to be used by the parent query. Depending on how the subquery is written, it can be executed once for the parent query or it can be executed once for each row returned by the parent query. If the subquery is executed for each row of the parent, this is called a correlated subquery.

A correlated subquery can be easily identified if it contains any references to the parent subquery columns in its WHERE clause. Columns from the subquery cannot be referenced anywhere else in the parent query. The following example demonstrates a non-correlated subquery.

Example: Select * From CUST Where '10/03/1990' IN (Select ODATE From ORDER Where CUST.CNUM = ORDER.CNUM)

65. What are the primitive operations common to all record management systems?

Addition, deletion and modification.

66. Name the buffer in which all the commands that are typed in are stored?

'Edit' Buffer.

67. What are the unary operations in Relational Algebra?

PROJECTION and SELECTION.

68. Are the resulting relations of PRODUCT and JOIN operation the same?

No.
PRODUCT: Concatenation of every row in one relation with every row in another.
JOIN: Concatenation of rows from one relation and related rows from another.

69. What is RDBMS KERNEL?

Two important pieces of RDBMS architecture are the kernel, which is the software, and the data dictionary, which consists of the system-level data structures used by the kernel to manage the database You might think of an RDBMS as an operating system (or set of subsystems), designed specifically for controlling data access; its primary functions are storing, retrieving, and securing data. An RDBMS maintains its own list of authorized users and their associated privileges; manages memory caches and paging; controls locking for concurrent resource usage; dispatches and schedules user requests; and manages space usage within its table-space structures.

70. Name the sub-systems of a RDBMS.

I/O, Security, Language Processing, Process Control, Storage Management, Logging and Recovery, Distribution Control, Transaction Control, Memory Management, Lock Management.

71. Which part of the RDBMS takes care of the data dictionary? How?

Data dictionary is a set of tables and database objects that is stored in a special area of the database and maintained exclusively by the kernel.

72. What is the job of the information stored in data-dictionary?

The information in the data dictionary validates the existence of the objects, provides access to them, and maps the actual physical storage location.

73. How do you communicate with an RDBMS?

You communicate with an RDBMS using Structured Query Language (SQL).

74. Define SQL and state the differences between SQL and other conventional programming Languages.

SQL is a nonprocedural language that is designed specifically for data access operations on normalized relational database structures. The primary difference between SQL and other conventional programming languages is that SQL statements specify what data operations should be performed rather than how to perform them.

75. Name the three major set of files on disk that compose a database in Oracle.

There are three major sets of files on disk that compose a database. All the files are binary. These are

1.) Database files
2.) Control files
3.) Redo logs

The most important of these are the database files where the actual data resides. The control files and the redo logs support the functioning of the architecture itself. All three sets of files must be present, open, and available to Oracle for any data on the database to be useable. Without these files, you cannot access the database, and the database administrator might have to recover some or all of the database using a backup, if there is one.

76. What is database Trigger?

A database trigger is a PL/SQL block that can defined to automatically execute for insert, update, and delete statements against a table. The trigger can e defined to execute once for the entire statement or once for every row that is inserted, updated, or deleted. For any one table, there are twelve events for which you can define database triggers. A database trigger can call database procedures that are also written in PL/SQL.

77. What are stored-procedures? And what are the advantages of using them?

Stored procedures are database objects that perform a user defined operation. A stored procedure can have a set of compound SQL statements. A stored procedure executes the SQL commands and returns the result to the client. Stored procedures are used to reduce network traffic.

78. What is Storage Manager?

It is a program module that provides the interface between the low-level data stored in database, application programs and queries submitted to the system.

79. What is Buffer Manager?

It is a program module, which is responsible for fetching data from disk storage into main memory and deciding what data to be cache in memory.

80. What is Transaction Manager?

It is a program module, which ensures that database, remains in a consistent state despite system failures and concurrent transaction execution proceeds without conflicting.

81. What is File Manager?

It is a program module, which manages the allocation of space on disk storage and data structure used to represent information stored on a disk.

82. What is Authorization and Integrity manager?

It is the program module, which tests for the satisfaction of integrity constraint and checks the authority of user to access data.

83. What are stand-alone procedures?

Procedures that are not part of a package are known as stand-alone because they independently defined. A good example of a stand-alone procedure is one written in a SQL*Forms application. These types of procedures are not available for reference from other Oracle tools. Another limitation of stand-alone procedures is that they are compiled at run time, which slows execution.

84. What are cursors give different types of cursors?

PL/SQL uses cursors for all database information accesses statements. The language supports the use two types of cursors
1.) Implicit
2.) Explicit

85. What is cold backup and hot backup (in case of Oracle)?

1. Cold Backup: It is copying the three sets of files (database files, redo logs, and control file) when the instance is shut down. This is a straight file copy, usually from the disk directly to tape. You must shut down the instance to guarantee a consistent copy. If a cold backup is performed, the only option available in the event of data file loss is restoring all the files from the latest backup. All work performed on the database since the last backup is lost.
2. Hot Backup: Some sites (such as worldwide airline reservations systems) cannot shut down the database while making a backup copy of the files. The cold backup is not an available option.

86. What is meant by Proactive, Retroactive and Simultaneous Update.

1. Proactive Update: The updates that are applied to database before it becomes effective in real world.
2. Retroactive Update: The updates that are applied to database after it becomes effective in real world.
3. Simulatneous Update: The updates that are applied to database at the same time when it becomes effective in real world.

MICRO PROCESSOR AND ITS APPLICATIONS

MICRO PROCESSOR AND ITS APPLICATIONS

1.Define Microprocessor?
Microprocessor is a multipurpose, programmable, clock-driven, register based
electronic device that reads binary instructions from a storage device called
memory, accepts binary data as input and processes data according to those
instructions, and provides as output.

2. What is Hardware and Software?
The physical components of the system i.e. computer are called Hardware.
Group of programs is called software.

3. Why the microprocessor is viewed as a programmable Device?
Microprocessor is programmable because it can be instructed to perform given
tasks within its capability. Microprocessor is designed to understand and execute
many binary instructions.

4. What is Central processing Unit ( CPU ) ? And Write the use of it.
CPU is a heart of the computer. Central processing Unit controls the operation
of the computer. In a microcomputer the CPU is a microprocessor. The CPU
fetches binary coded instructions from memory, decodes the instructions into a
series of simple actions and carries out these actions in a sequence of steps.

5. What is a chip?
A chip is also called an integrated circuit. Generally it is a small, thin piece
of silicon onto which the transistors making up the microprocessor have been
etched. A chip might be as large as an inch on a side and can contain tens of
millions of transistors. Simpler processors might consist of a few thousand
transistors etched onto a chip just a few millimeters square.

6. What is System Bus?
The System bus is a communication path between the microprocessor and
peripherals. It is nothing but a group of wires to carry bits.

7. What is Address Bus?
The address bus consists of 16, 20, 24 or 32 parallel signal lines. On these
lines the CPU sends out the address of the memory location that is to be written to
or read from. The number of address lines determines the number of memory
locations that the CPU can address. If the CPU has N address lines, then it can
directly address 2N memory locations. Simply, we can say that Address Bus is
used to carry the address.

8. What is Data Bus?
The data bus consists of 8, 16, or 32 parallel signal lines. The data bus lines
are bidirectional. This means that the CPU can read data in from memory or from
a port on these lines, or it can send data out to memory or to a port on these lines.
Simply we can say that data bus is used to carry the data.

9. What is Assembly Language?
A medium of communication with a computer in which programs are
written in mnemonics. Binary instructions are given abbreviated names called
mnemonics, which form the assembly language for a given processor.

10. What is Machine Language?
The binary medium of communication with a computer through a designed
set of instructions specific to each computer.

11. What is Bit-Slice processor?
For some Applications , general purpose CPUs such as the 8080 and 6800
are not fast enough or do not have suitable instruction sets. For these
applications ,several manufacturers produce devices which can be used to build
the custom CPU. This family includes 4 bit ALUs, multiplexers, sequencers and
other parts needed for custom building a CPU. The term slice comes from the
fact that these parts can be connected in parallel to work with 8 bit words, 16-
bit words, or 32 bit words.

12. What is microcontroller?
Microcontroller is a Device that includes microprocessor, memory and
I/O signal lines on a single chip, fabricated using VLSI technology.

13. List the main applications of 8 bit microprocessors?
8 bit microprocessors is used in a variety of applications such as
appliances, automobiles, industrial process and control applications.

14. Write the uses of microprocessors in Medical Instrumentation field?
Patient Monitoring in Intensive Care Unit, Pathological Analysis and the
measurement of parameters like blood pressure and temperature.

15. Define Real Time Systems :
Real Time Systems are those in which timeliness is as important as the
correctness of the outputs, although this does not mean that they have to be “fast
systems”.

16. List the limitations of 8 bit microprocessor:
• Lower Execution Speed
• It can address less memory size
• Few instructions are available

17. What do you mean ‘ Data Width’?
Data Width is the width of the ALU. An 8 bit ALU can add / subtract/
multiply etc.. two 8 bit numbers . In many cases, the external data bus is the
same width as the ALU, but not always. The 8088 had a 16 bit ALU and 8 bit
bus , while the modern Pentiums fetch data 64 bits at a time for their 32 bit
ALUs.

18. Draw and specify the complete bit configuration of 8085 flag Register?
D7 D6 D5 D4 D3 D2 D1 D0
S Z AC P CY
S- Sign Flag . If D7 =1 , then sign flag is set, otherwise rest.
Z-Zero flag. If ALU operation results in zero, then this flag is set,
Otherwise it is reset.
AC-Auxilliary flag. In an arithmetic operation ,when a carry is generated
by digit D3 and passed on to digit D4, the AC flag is set.
Otherwise it is reset.
P-Parity Flag. If the result of an arithmetic or logic operation has an even
number of 1’s then this flag is set. Otherwise it is reset.
CY-Carry Flag. If an arithmetic operation results in a carry, the carry flag
is set. Otherwise it is reset.

19. List the four operations commonly performed by MPU( Micro processing
Unit)?
• Memory Read : Reads data (or instructions) from memory.
• Memory Write: Writes Data (or instructions) into memory.
• I/O Read: Accepts data from input devices.
• I/O Write: Sends data to output devices.

20. Write about RST pins in 8085?
In 8085 ,three RST pins are available, such as RST 7.5 ,RST 6.5 , RST
5.5. RST represents Restart Interrupts. These are vectored interrupts that
transfer the program control to specific memory locations. They have higher
priorities than the INTR interrupt. Among these three, the priority order is
7.5,6.5,5.5.

21. List the control and status signals available in 8085.
ALE , RD, WR, IO/M, S1, S2
ALE-Address Latch Enable
RD – Read Control Signal
WR – Write Control Signal
IO/M - To specify I/O or memory operation
S1 , S2 – Status signals

22. What are the limitations of 8085 MPU?
(i) The lower order address bus of the 8085 microprocessor is multiplexed
(time shared) with the data bus. The buses need to be demultiplexed.
(ii) Appropriate control signals need to be generated to interface memory
and I/O with the 8085.

23. Compare the 8 bit microprocessors 8080A and 8085.
8080A is the predecessor of 8085. 8085 has the instruction set of
8080A plus some additional ones. Program written for 8080A will be executed
by 8085. 8085 and 8080A are not pin compatible. Both require a +5V power
supply.

24. Define Register Relative Addressing Mode.
Register Relative Addressing Mode : The Effective Address is Calculated
by the sum of 8- or 16 bit displacement and the contents of a base Register or an
index Register.
E.A. = content of(BX or BP or SI or DI) + (8 bit displacement (sign
extended ) or 16 bit displacement
Physical Address = E.A +(DS)*1610

25. Define Immediate Addressing.
An 8 bit or 16 bit immediate data follows the instruction. For e.g MOV
AX,5020H instruction transfers a word 5020H to the AX register .

26. Define Direct Addressing mode :
A 16 bit offset address of the data memory location is specified with
reference to the DS segment starting address.
For.E.g MOV [1020H],5020H instruction transfers a word 5020H to the data memory
location at 11020H if DS=1000H.

27. Define Relative based indexed addressing mode:
Relative Based Indexed Addressing Mode : Effective Address is calculated by the
sum of 8- or 16 bit displacement and a based indexed address.
E.A.= (BX or BP) + (SI or DI) +( 8 bit displacement (sign extended ) or 16 bit
displacement)
Physical Address= E.A + (DS)*1610

28. List the branch related addressing mode:
• Intra segment Direct
• Intra segment Indirect
• Inter segment Direct
• Inter Segment Indirect

29. List the functions of Bus Interface Unit in 8086.
• Sends out addresses
• Fetches instructions from memory
• Reads data from ports and memory
• Writes data to port and memory

30. Write any two advantages of segment registers in 8086
a. It allows the memory capacity to be 1MB even though the address
associated with individual instructions are 16 bits wide.
b. It allows the instruction,data, or stack portion of a program to be more
than 64KB long by using more than one code, data, or stack segment

31. What is the use of Instruction pointer in 8086 ?
Instruction pointer holds the 16 bit address of the next code byte within the
code segment. The value contained in the IP is called effective address or offset.
It contains the distance from the base address to the next instruction byte to be
fetched.

32. Write about the auxiliary carry flag used in 8086 ?
It is set if there is a carry out of bit 3 during an addition or a borrow by bit
3 during a subtraction. This flag is used exclusively for BCD arithmetic.

33. When the Overflow flag is set ?
For addition of 16 bits, this flag is set when there is a carry into the MSB
and no carry out of the MSB.

34. Define Register addressing mode:
Datum is in the register that is specified by the instruction
E.g : MOV CX,AX (16 bit operand)
MOV CL,AL ( 8 bit operand)

35. Define Register Indirect Addressing mode:
Effective address of the datum is in the base register BX or an index
register that is specified by the instruction.

36. Define Register relative addressing mode:
The effective address is the sum of an 8- or 16 bit displacement and the
contents of a base register or an index register.

37. Define Based Indexed addressing mode:
The effective address is the sum of a base register and an index register ,
both of which are specified by the instruction. It is also called as Base related
Indexed addressing.

38. Define Intra segment direct addressing mode:
The effective branch address is the sum of an 8- or 16 bit displacement
and the current contents of IP.

39. Define Intra segment Indirect addressing mode:
The effective branch address is the contents of a register or memory
location that is accessed using any of the data related addressing modes except
the immediate mode. The contents of IP are replaced by the effective branch
address.

40. Define Inter segment addressing mode:
It replaces the contents of IP with part of the instruction and the contents
of CS with another part of the instruction.