January Mock Corrections

Paper1

1Bi) The system stores floating point numbers in normalised form using 2's complement with a 12-bit mantissa and a 4-bit exponent as follows.

Num1             A802                101010000000  0010            -2.75

Bii) Why should floating point numbers be stored in normalised form?

To maximize precision in a given number of bits to maximize the accuracy in a given number of bits, and to minimize rounding errors.


2B)  A normalised floating point representation uses an 8-bit mantissa and a 4-bit exponent, both stored using two's complement format.

1.0110000    0010
=-2.5


2C) write the normalised floating point representation of the denary value 12.75.
           0.1100110        0010

Q3E)  Run-length encoding (RLE) is an example of  compression method that could be used to reduce the amount of memory required to store the icon.
Describe the principle used by RLE to compress a file and explain why RLE is an appropriate compression method for compressing images such as icons.

Identify multiple data values/ colours that are the same and represents them as one data values. E.g b,b,b,b=4b. Icons contain sequences of pixels that are the same colour. RLE is a lossless compression so the quality will not be effected.

5B) If an image required 3000 colours - how many bits would be required for the colour depth and why?

12 bits is enough because it is the smallest number of bits that can accommodate 3000 colours. 12 bits can represent a max number of 4096 colours which is more than 3000.