Computer Science Questions
and Answers
Chapter
- 1 Configuring a Computer
Question Set 1
1. Name the components of CPU
Ans.
a) ALU b) PC c) Accumulator d)
MAR e) IR f) ID
g) MDR
2. What is the use of registers in CPU?
Ans. It is used to store intermediate data and instructions.
3. What is the function of MAR?
Ans. It specifies the address of memory location from which data or instruction is to be accessed
or to which the data is to be stored.
4.
What is the function of MDR / MBR?
Ans.
It contains the data to be written into or read from memory location addressed
by MAR.
5.
What is program counter?
Ans.
It keeps track of the memory address of the instruction that is to be executed next.
6.
What is the function of IR?
Ans.
It contains the instruction that is being executed.
7. What is the purpose of Instruction Decoder?
Ans. It decodes the instructions.
8. What is a data bus?
Ans.
It carries a word to or from memory.
9. What is an address bus?
Ans.
It carries memory address.
The width of address bus equals the number of bits in the
MAR.
10. What is the function of control
bus?
Ans. It carries signals between the units of the computer.
11. Name different I/O ports.
Ans. Port is a socket on the back of computer.
Different types of ports are serial ports, parallel ports and USB ports.
12. What is meant by plug and play cards?
Ans.
It enables the user to add devices to computer.
Question Set 2
1. Explain USB Port (Universal Serial Bus).
Ans. a. It is a high speed serial bus
b. It is a plug and play interface between computers and add on devices.
2. Give the specifications of Laser printer.
Ans. a. Resolution varies from 600 to 1200 dots per inch. b. Speed varies from 4 PPM to 24 PPM.
c. Buffer size varies from 4MB to 32 MB
d. Can print color images.
3. Give the specifications of dot matrix printer.
Ans. a. Print head normally has 9 pins to 24 pins.
b. Speed varies from 30 to 300 characters per second. c. Buffer size varies from 1K to 64 K.
4. Give the specifications of inkjet printer.
Ans. a. Resolution is around 300 dots per inch.
b. Speed varies from 1PPM to 12 PPM
c. Buffer size varies from 1 MB to 4 MB.
Question Set 3
1) Write
a note on computer maintenance. Ans: a. Avoid heat dust and noise
b. Periodic updates and enhancements
c. Installing fire walls and anti virus. d. In house software maintenance
e. Computer periodic checkup.
2) What are the possible threats to a computer
system and how to provide security?
Ans: Threats a. Privacy
b. Integrity
c. Environmental damage
d. Human threats e.
Software threats
f. Unauthorized access g. Computer viruses
Security
a. Physical protection of machine and media. b.
Giving passwords and users ID
c. Using Licensed software
d. Use of Cryptography
e.
Use of Spike busters and UPS
3) Explain the typical causes of computer failures.
Ans: a. Break down of components.
b. Excessive dust or humidity
c. Virus
e. Corrosion
4) Write a note on Computer
virus.
Ans: Viruses are collection
of coded instructions which are self replicating. When a virus attaches itself to another file it infects it. They are normally inactive until infected
program is run. They are broadly classified
into three categories.
a. Boot infectors
b. System
infectors
c.
Executable program infectors
Boot infectors: Create bad sectors. They remain in the memory until the system is shutdown. System infectors It infects the hard disk or: bootable
floppies which may contain system files. Executable program infectors:
These are dangerous
and devastating. They spread to
almost any executable
program attaching themselves
to programming files.
5. Explain the cache memory in detail.
Ans: Cache memory is a small and fast memory between CPU and main memory. It is extremely fast compared to normal memory. Transferring
data between main memory and CPU causes delay because RAM is
slower than CPU. Cache memory stores copies of data from most frequently used main memory locations. When
processor needs to read from or write to a location in main memory, it first checks whether a copy of data is in the cache. If so processor immediately reads or writes to cache. Computers use multilevels of cache such as Level1(smallest)and Level2 cache.CPU resident cache is known as L1 or primary cache (16 to 32 KB) to 512 KB.Cache is also added to mother board also known as L2 cache (512 KB to 1024 KB). Higher end systems can have as much as 2 MB of L2 cache on mother board.
6. Write a note on components of motherboard.
Ans: 1) Bus : -
a. Address Bus b. Data
Bus
c. Control Bus
2) Expansion slots:
They serve the purpose of adding functionality to the computer.
a. ISA : Industrial standard architecture.
b. PCI : Peripheral component interface
c. AGP : Accelerated Graphic port.
3) CACHE
Memory: It is a small fast memory that resides between
CPU and main memory.
4) CMOS (Complementary Metal Oxide Semiconductor Battery )
5) I-O Ports ( Input –Output Ports ): Serial , Parallel , USB etc.,
7. Explain the different factors affecting the processing speed of CPU.
• Ans: CPU Speed/Clock speed: Speed of CPU also known as clock speed. The clock speed is the number
of
instructions
executed by
the
CPU
in
one
second
It is measured in megahertz(million instructions per second). The average speed of a new CPU is about 1000MHz to 4000 MHz.(1 to 4 giga hertz).
• Instruction set: The number of instructions decide the efficiency of a CPU. More the instructions , less efficient is the CPU and less the instructions, More efficient is the CPU.
• Word size/Register size: The
size of registers determines the amount of data the computer can work with at a time. Normally it
is 32 bits. Smaller the size of register, slower will be the computer. . It is also known as Word size.
It varies from 16 bits to 128 bits.
• Data bus capacity: Width of a data bus determines the largest number of bits that can be transported at one time.
• Cache Memory size: Cache memory is a high speed memory. Greater the cache, faster a processor runs. Most modern
processors
can execute
multiple instructions per
clock cycle which speeds
up a program. Some CPU’s have storage for instructions and data built inside the processor chip . This is called internal cache or L1 cache memory.
• Memory Size: The amount of PRIMARY STORAGE (RAM) determines the size of program that can be kept in primary storage, which is faster than secondary
storage. There by the speed of computer increases. The size of RAM varies from 64 MB to 4 GB.
8. Explain the General Structure of CPU.
Ans: Program counter: This register stores address of next instruction to be executed.
Memory address register (MAR): This register specifies address in memory where information can be found.
This register is also used to point to a memory locations where information can be stored.
Memory buffer register: This register acts as an interface between CPU and memory. When CPU
issues a Read Memory command, instruction is fetched and placed in MB register.
Instruction register-This stores a copy of current instruction.
Instruction decoder (ID): ID is an electronic hardware, which decodes instructions.
The instructions are further broken down into a set of micro operations, so that they can be executed directly.
General purpose registers: They are used to store data. There are 6 GP registers. These are used for storage of data as needed by the program.
Arithmetic logic unit: The basic arithmetic operations such as addition,subtraction,multiplication and division
are
carried
out
here.
These operations need
atleast
two
operands,
one
which
is stored in accumulator and the other in the MBR. After the manipulation of data in ALU, the result is transferred to accumulator.
Accumulator:
During
processing
the intermediate
data
needed
for future processing is stored in accumulator. The contents of ACC are used by ALU for operations and later by MBR holds the final result for further action.
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