Computer Systems

Question 1

which part is the mantissa and what does it determine?

2. 123 × 10^5
3. 1234× 10^7

Answer 1

the mantissa is the decimal part of the number.
(2123) (1234)
It determines the degree of accuracy or precision with which the numbers can be represented.

Question 2

what is 123 in binary?

Answer 2

01111011

Question 3

whats 10110011 in denary?

Answer 3

179

Question 4

which part is the exponent and what does it determine?

2. 123 × 10^5
3. 1234× 10^7

Answer 4

the exponent is the raised to the power of.
(5)
(7)
It determines the range of numbers that can be represented.

Question 5

what is extended ASCII?

Answer 5

characters are stored in binary form. each character is stored in one byte (8 bits) it allows for the representation of 256 different characters

Question 6

Describe the vector graphics method of graphic representation

Answer 6

Vector graphics store a picture by storing each objects attribute – e.g. the instructions to draw the shape.

Question 7

How do you store a rectangle with vector graphics (with it’s attributes)?

Answer 7

Rectangle - (height, width, x co-ordinate, y co-ordinate, fill colour, line colour)

Question 8

How do you store a Ellipse with vector graphics (with it’s attributes)?

Answer 8

Ellipse - (cx, cy, rx, ry, fill colour, line colour)

Question 9

How do you store a Line with vector graphics (with it’s attributes)?

Answer 9

Line - (x1, y1, x2, y2, line colour)

Question 10

How do you store a Polygon with vector graphics (with it’s attributes)?

Answer 10

Polygon - any shape with 3 of more sides - (x1, y1, x2, y2, x3, y3, fill colour, line colour)

Question 11

Describe the bit-mapped method of graphics representation.

Answer 11

An image is made up of pixels, each pixel has a binary value corresponding to a colour.
•Number of bits per pixel depends on the number of
colours in the image – more colours, more bits.
•the number of pixels in a given area is the resolution
more pixels= more space taken up.
•they are often compressed to reduce storage size and
make them easier to download.

Question 12

what are the parts of the processor?

Answer 12

•Control Unit – controls the sequencing of fetching,
decoding and executing instructions.
•Arithmetic Logic Unit – performs all calculations and
logical operations
•Registers – temporary memory locations within the
processor.

Question 13

what does the control unit do?

Answer 13

It controls the sequencing of fetching, decoding and executing instructions.

Question 14

what does the ALU do?

Answer 14

executes the programmes instructions, carrying out calculations, Boolean operations and comparisons.

Question 15

what do the registers do?

Answer 15

temporary memory locations within the processor.

Question 16

Describe the two types of buses.

Answer 16

Address Bus – this identifies the memory location that is going to read from or written to.
Data Bus – this transfers the data between the processor and memory, and vice-versa.

Question 17

What is RAM?

Answer 17

(Random Access Memory)
•when a program is running the data processed by the
processor is temporarily stored in RAM. RAM will hold
data until it is needed by the processor.
•When the computer system shuts down, RAM is cleared .
•All memory locations within RAM is given a unique
address so that the computer can read and write data to
that location correctly.
•The more RAM that is available, the more programs it is possible to run concurrently (at the same time) without slowing system performance.

Question 18

what is an interpreter? list its advantages and disadvantages.

Answer 18

Translates the program one line at a time into machine code and executes immediately. Machine code is not retained, so must be translated each time.
Advantages-
•good for testing as errors can be highlighted right
away.
Disadvantages-
•program will stop after first error encountered so may
take several runs to find them all.
•execution time is slow in comparison to compiled code

Question 19

what is an compiler? list its advantages and disadvantages.

Answer 19

Translate whole program, and then save machine code version. Translate code can be run again, and again. Used for programs that are ready for release.
Advantages-
•all errors can be found in a single pass
•once the program has been compiled it can be
executed many times without recompiling.
disadvantages-
•it cannot locate the the exact location of the error
•if it contains errors, the program will crash.
Programmers must revisit source code, identify and
correct errors and recompile

Question 20

how do you reduce energy consumption?

Answer 20

Settings on monitors – reduce brightness, activate efficiency mode, use energy efficient monitors.

Power down settings – power-down after a period of inactivity, control setting for single components.

Leaving computers on standby – power consumption is reduced.

Question 21

Describe the role of firewalls.

Answer 21

A firewall protects against hackers. When an external computer tries to access a computer, the firewall decides if the external computers access should be granted or denied. It does this by checking incoming data packets against a set of rules.

Question 22

Describe the use made of encryption in electronic communications.

Answer 22

•Encryption codes the information so that if it is
intercepted then they would not be able to make
sense of it. It can only be understood by the sender
and received.
•Use of encryption public keys to encrypt the data so it
cannot be understood and use of a private key to
decrypt the data.