Final Revision

Question 1

What is the formula for calculating positional notation?

Answer 1

dn x R^n-1 + dn-1 x R^n-2 + … + d2 x R^1 + d1 x R^0

di: the digit at position i
R: the base
n: number of digits

Question 2

What is the algorithm to convert to base 10?

Answer 2

While number is not equal to 10
Divide by new base
Store remainder
Replace value with quotient

//Read numbers in reverse order

Question 3

Describe what happens when transferring electrical signals.

Answer 3

• an analog signla continueally fluctuates up and down in voltage
• a digital signal has only a high or low state (binary)
• All electrical signals (analog and digital) degrade as they move down the line.
• A digital signal is re clocked periodically to its original shape.

Question 4

What is pulse code modulation?

Answer 4

Variation in a signal that jumps sharply between two extremes.

Question 5

What does it mean to reclock?

Answer 5

The act of reasserting the original digital signal before too much degradation occurs.

Question 6

What is the formula to work out 10’s compliment of a number

Answer 6

negative(i) = 10^k - i

Question 7

What is overflow?

Answer 7

Occurs when the value being computed can not fit into the number of bits that are allocated for the result.

Question 8

Data compression

Answer 8

the reduction in the amount of space needed to store a piece of data or the bandwidth to transmit it.

Question 9

What is sampling?

What is Quantisation?

Answer 9

Sampling: Perodically measuring the voltage
quantisation: representing voltage as a finite no of bits

to reproduce a sound reasonably, there needs to be 40,00 samples per second

Question 10

What is a CD? How does it work? What are its formats?

Answer 10

Stores information digitally, in a spiral, and has tracks. a red laser is shone on the surface, and reflected light is picked up by a receptor and translated into binary digits.

It has pits ( reflect poorly) and lands (reflect well). they represent binary 0 and 1 respectively.

• CD-ROM read-only memory
• CD-DA digital audio
• CD-WORM write once, read many
• CD-RW/CD-RAM both read from and written to

Question 11

How is colour represented?

Answer 11

Colour is expressed as a RGB value, 3 numbers that indicate the contribution of each of the primary colours

COlour depth refers to the number of bits used to represent a colour.
HiColour uses 16 bits - 5 for each colour then the spare bit sometimes used to indicate transparency.
TrueColour uses 24 bits, 8 bits used to represent each of the primary colors.

Question 12

What is raphster graphics?

Answer 12

Treats images as a collection of pixels. common formats include BMP,PNG, Jpeg and GIF

Question 13

What is a pixel?

What is resolution?

Answer 13

Pixel: a dot of colour in an image
resolution: The number of pixels in an image (or device)

Question 14

Describe BMP

Answer 14

Bitmaps
Uses true colour, or less to reduce file size
well suited too RLE

Question 15

Describe GIF

Answer 15

• file explicitly uses a pallet of 256 colours, but this palette varies from different images. This is known as indexed colour
• Each pixel uses 8 bits or less
• animated GIFS are a sequence of of images

Question 16

Describe PNG

Answer 16

• intended to replace GIF
• Gretaer compression ratio and can express more colours
• No animation

Question 17

Describe JPEG

Answer 17

-averages hues over short-distances - the human eye tends to blur colours together over short distances

Question 18

What are vector graphics?

Answer 18

• Treat images as a collection of geometric shapes.
• Examples of file types is Flash and SVG
• Good for lineart
• bad for real world images

Question 19

What are the two types of representing video?

Answer 19

Temproal: a technique based on the differences between consecutive frames. If most of an image has not changed, why should we waste space on duplicating information.

Spartial: a technique based on removing any repeating information within a frame. This is essentially the same problem faced with when compressing still images.

Question 20

What is a computer?

Answer 20

A programmable electronic device that can store, retrieve and process data.

Question 21

What is machine language?

What are the characteristics of it?

Answer 21

The language made up of binary coded instructions built into the hardware of a particular computer and used directly by the computers

Characteristics:

• Every processor has a unique set of machine code instructions
• The digital logic of the CPU reconises the binary representation of the instructions
• Every machine language does one low level task.

Question 22

What is a virtual computer?

What is PEP/8?

Answer 22

A virtual computer is a hypothetical machine designed to demonstraight the important features of a real world computer we want to illustraight.
PEP/8 is a virtual computer with 39 machine code instructions. it has 64Kb of memory.

Question 23

What is assembly language?

Answer 23

A language that has mnemonic codes to represent each of the instructions and translates them into the machine language.

Question 24

What is a gate?

What is a circuit?

Answer 24

Gate: A device that performs a basic operation on electircal signals

Circuit: Gates combined to perform more complicated tasks

Question 25

What is a transistor?

Answer 25

A device that acts as either a input wire conducting a current or a resistor that blocks the current depending on the input signal. It is like a switch with no moving parts.
they are made from a semi conductor which is neither a good conductor or a good insulator.

Question 26

What is a sequential circuit?

What is a combination circuit?

Answer 26

Sequential circuit is one in which the output depends on both the current state of the circuit as well as the inputs

Combination circuit is one in which its output depends solely on the inputs

Question 27

What is a multiplexer?

Answer 27

A type of circuit that accepts a few input control signals to determine which of the input data signals are routed to the output signal

Question 28

What is a S-R latch?

Answer 28

a type of memory circuit

• S and R are never both 0
• X and Y are always the compliment of each other
• Sequential circuit
• X is the current state of the circuit

Question 29

What is an integrated circuit?

Answer 29

a piece of silicon in which multiple gates have been embedded. It is mounted on a piece of plastic or silicon, with pins along the edge that can be solderd to circuit boards or inserted into approiote sockets. The CPU is the most important chip.

Question 30

what are the types of parallelism?

Answer 30

• Bit-level parallelism
Bits can be processes simultaneously
Ex: Increasing word size
• Instruction-level parallelism
Instructions can be executed simultaneously
Ex: Pipe-lining (overlapping instructions)
Ex: Super-scalar (multiple execution units)
• Data-level parallelism
Data subjected to the same operation sequence simultaneously
Ex: Calculation of all students’ GPAs simultaneously
• Task-level parallelism
Entire tasks can be completed simultaneously
Ex: Google servers (simultaneous independent searches
Ex: “Pipelined” processors

Question 31

What is a Shared Memory Parallel Processor?

Answer 31

Communicates through shared memory

Question 32

What are embedded systems?

Answer 32

Embedded system are computers that are designed to perform a narrow range of functions as part of a larger system. They are typically housed on a single microchip and all programs stored in ROM.