NATIONAL OPEN UNIVERSITY OF NIGERIA
14-16 AHMADU BELLO WAY, VICTORIA ISLAND LAGOS
MARCH/APRIL 2016 EXAMINATION
SCHOOL OF SCIENCE AND TECHNOLOGY
COURSE CODE: CIT381
COURSE TITLE: File Processing and Management
Time: 2 hrsCourse Credit Unit: 2
Instruction: Attempt any four (4) questions. Each question carries 17½ marks
1 a. Explain, in writing, what you understand by ”a path name” (5 marks)
The series of directory names, culminating in the file name itself, constitutes a pathname for the file.
b. Write briefly on the following file operations. (1½ mark each = 7½ marks)
i) Creating a File:- When creating a file, a space in the file system must be found for the file and then an entry for the new file must be made in the directory. The directory entry records the name of the file and the location in the file system.
ii) Opening a File:- Before using a file, a process must open it. The purpose of the OPEN call is to allow the system to fetch the attributes and list of secondary storage disk addresses into main memory for rapid access on subsequent calls.
iii) Closing a File:- When all the accesses are finished, the attributes and secondary storage addresses are no longer needed, so the file should be closed to free up internal table space.
iv) Writing a File:- To write a file, a system call is made specifying both the name of the file and the information to be written to the file. Given the name of the file, the system searches the directory to find the location of the file.
v) Reading a File:- This call returns the next entry in an open directory. Formerly, it was
possible to read directories using the usual READ system call, but that approach has the disadvantage of forcing the programmer to know and deal with the internal structure of directories
c. List two (2) types of pathname (5 marks)
Absolute Path name :- With this path name, each file is given a path consist of the path from
the root directory to the file. As an example, the file in the lower lefthand corner of Figure 09 has the pathname User_B/Word/Unit_A/ABC. The slash is used to delimit names in the sequence.
Relative Path name:-
2 a) What types of file extensions will the following contain:
File Type
Extension
A movie in a Video CD
.mpg or .mpeg
A word processed file
.doc or .dot
A file in a Musical CD
.jpg or .jpeg
A Scanned image
A picture taken with a digital camera
.jpg
An Excel file
.xls
b. What is the full meaning of the following acronyms?
S/n
Acronym
Meaning
i
CBIS
Computer Based Information System
ii
CPU
Central Processing Unit
iii
RAM
Random Access Memory
iv
ROM
Read Only Memory
v
FAT
File Allocation Table
vi
DVD
Vii
• GIF
• RTF
• VFS
Portable Document Format
General Interchange Format
Rich Text Format
Virtual File Systems
c. What do you understand by blocking of records? (5½ marks)
Records are the logical unit of access of a structured file, whereas blocks are the unit of I/O with secondary storage. For I/O to be performed, records must be organized as blocks
3 a. What is file management system?(5½ marks)
The file management system, FMS is the subsystem of an operating system that manages the data storage organisation on secondary storage, and provides services to processes related to their access.
b. Write briefly on the following:
(i) Disk quotas:- Multiuser operating systems prevent people from hogging too much disk space by providing a mechanism for enforcing disk quotas.
(ii) Volume:- “a collection of addressable sectors in secondary memory that an OS or application can use for data storage.
c. List three (3) objectives of file management system (6 marks: 2 marks each for any three)
Data management
Protection
Concurrency
Validity
4 a. what are backups? (3½marks):- Backups is the process that involves keeping another copy of the data on some other machine or device so that the copy could be used in case of a system failure.
b. Outline two (2) types of backups you know (4 marks)
Full dump:- simply refers to making a backup copy of the whole disk on another disk or machine.
Incremental dump:- this make a full dump periodically (say monthly or weekly) and to make a daily dump of only those files that have been modified since the last full dump.
c. Explain, in writing, what you understand by user authentication (5 marks)
A major security problem for operating systems is authentication. The protection system depends on the ability to identify the programs and processes currently executing, which in turn depends on the ability to identify each user of the system. The process of identifying users when they log on is called user authentication.
d. How can user authentication be implemented? (5 marks)
User possession (a key or card)
User knowledge (a user identifier and password)
User attributes (fingerprint, retina pattern, or signature).
5. a) List and explain the Logical Components of a file. (5½marks)
A field is the basic element of data
A record is a collection of related fields that can be treated as a unit by some application program
A file is a collection of related records
b) Outline and explain, in writing, any three (3) types of file you know (6 marks)
.exe:- DOS/ Windows program or a DOS/ windows Self Extracting Archive
.dll:- Dynamic Link Library. This is a compiled set of procedures and/or drivers called by another program
.ppt:- A presentation file (for slide shows)
.xls, .123:- Spreadsheet files
.mp3:- Audio Files on both PC and Mac
c) List three (3) File Organisation Criteria (6 marks: 2 marks each for any three)
Short access time
Ease of update
Economy of storage
Simple maintenance
Reliability.
6. a. Differentiate between the following with regards to files operations
(i) Truncating and deleting (1½ marks):- The user may erase some contents of a file but keep its attributes. Rather than forcing the user to delete the file and then recreate it, this operation allows all the attributes to remain unchanged, except the file size. While To delete a file, the directory is searched for the named file. Having found the associated directory entry, the space allocated to the file is released (so it can be reused by other files) and invalidates the directory entry.
(ii) Writing and appending (1½ mark):- To write a file, a system call is made specifying both the name of the file and the information to be written to the file. Given the name of the file, the system searches the directory to find the location of the file. While Appending a file is a restricted form of WRITE call. It can only add data to the end of the file.
(iii) Reading and repositioning (1½ mark):- To read a file, a system call is made that specifies the name of the file and where (in memory) the next block of the file should be putWhile When repositioning a file, the directory is searched for the appropriate entry, and the current file position is set to a given value
(iv) Creating and opening (1½ marks):- When creating a file, a space in the file system must be found for the file and then an entry for the new file must be made in the directory While Before using a file, a process must open it. The purpose of the OPEN call is to allow the system to fetch the attributes and list of secondary storage disk addresses into main memory for rapid access on subsequent calls.
b. List and explain three (3) operations that are to be performed on a directory.
(2 marks each for any three = 6 marks)
Create a File:- New files need to be created and added to the directory.
Delete a File:-When a file is no longer needed, we want to remove it from the directory. Only an empty directory can be deleted.
Open a File:-Directories can be read.
Close a File:-When a directory has been read, it should be closed to free up internal table space.
c. List two (2) methods of improving file system performance. (4 marks)
Block Caching:- The most common technique used to reduce disk accesses is the block
cache or buffer cache a cache is a collection of blocks that logically belong on the disk, but are being kept in memory for performance reasons
Reduction in Disk Motion:- Another important technique is to reduce the amount of disk arm motion by putting blocks that are likely to be accessed in sequence close to each
other, preferably in the same cylinder.
SEPTEMBER/OCTOBER 2015 EXAMINATION
1(a) Write short note on the following
(i) System Software
(ii) Application Software
(iii) Random Access
(2 marks each)
(b) List and explain five (5) uses of the Internet (11.5 marks)
3 (a) Write short note on each of the following
(i) Biometrics
(iii) Data Corruption:- refers to errors in computer data that occur during transmission or retrieval, introducing unintended changes to the original data.
(3 marks each)
(b) List any three (3) causes of data loss (6 marks)
Natural phenomenon such as: fire, flood, earthquakes, wars, riots or attacks from rodents
Hardware or software errors: CPU malfunctions, unreadable disks or tapes, telecommunication errors, program bugs
Human errors: incorrect data entry, wrong tape or disk mounted, wrong program run, lost disk or tape.
(c) Mention any two levels of security measures in system protection (2.5 marks)
Physical: The site or sites containing the computer systems must be physically secured against armed or surreptitious entry by intruders.
Human: Users must be screened carefully to reduce the chances of authorising a user who then gives access to an intruder (in exchange for a bribe, for example).
Network: Much computer data in modern systems travels over private leased lines, shared lines such as: the Internet, or dial-up lines.
(b) Write short note on each of the following:
Data Validation:- is the process of ensuring that a programme operates on clean, correct and appropriate data
Data Dictionary:- is the description of the data stored in a database.
Denial of Service:- is aimed not at gaining information or stealing resources but rather at disrupting legitimate use of a system or facility.
( c). List three implementation of file protection (6 marks)
File Naming
Password Protection
Access Control
6(a) Explain a sorting algorithm to a lay man? (6 marks)
sorting algorithm is a prescribed set of well-defined rules or instructions that puts elements of
a list in a certain order.
(b) List any five different sorting techniques. (5 marks)
Quick Sort
Heap Sort
Merge Sort
Insertion Sort
Bubble Sort
Shell Sort
Bucket Sort
OCTOBER/NOVEMBER 2014 EXAMINATION
3(b) Outline three (3) different types of File Directory Structure (41/2 marks)
Single-Level Directory
Two-Level Directory
Tree-Structured Directory
Acyclic Graph Directory
4( a) Describe Free Space Management (4 marks)
Files are normally stored on disk, so management of disk space is a major concern to the file system designers. To keep track of free disk space, the system maintains a free space list.
4(b) Outline three (3) methods used in Free Space Management (41/2 marks)
Bit tables
Chained free portion
Indexing, and
Free block list.
4(c ) List and explain three measures of protecting systems ( 9 marks)
Physical: The site or sites containing the computer systems must be physically secured against armed or surreptitious entry by intruders.
Human: Users must be screened carefully to reduce the chances of authorising a user who then gives access to an intruder (in exchange for a bribe, for example).
Network: Much computer data in modern systems travels over private leased lines, shared lines such as: the Internet, or dial-up lines.
5(a) List and explain three (3) different ways through which a file could be protected? (9 marks)
Protected:- This can be implemented by allowing only users to see the files they have created.
Password Protection:-This scheme associates a password to each file.
Access Control:-An access list is associated with each file or directory. The access list
contains information on the type of users and accesses that they can do on a directory or file
5(b) Identify and explain two (2) tips for management of electronic files ( 4 marks)
Organise by file types. Make applications easier to find by creating a folder called Program Files on your drive and keeping all your applications there.
One place for all. Place all documents in the My Documents folder and nowhere else. So whether it’s a spreadsheet, a letter or a PowerPoint presentation, it goes here. This will make it easier to find things and to run backups.
5(c ) List three (3) example of Navigational File Manager (41/2 marks)
Windows Explorer
Mac OS X Finder
XTree / ZTreeWin
XYplorer
6(c ) Outline three (3) types of Search (41/2 marks)
Graph Search
Tree Search
List Search
MARCH/APRIL 2014 EXAMINATION
1. (a) What is a File? (5 marks)
A file consists of a number of records, A file is a collection of related records.
3a. . What is FAT? (5 marks)
FAT is a sort of data structure or table used to keep track of the portions assigned to a file