Important Things to Memorise for Higher Computing
Range of numbers that can
be represented using n bits
0 to 2n – 1
How to work out two’s
complement
Floating point numbers
Calculating the file size of a
bit map graphic
Number of colours
represented by a bit-depth of
n bits
Step 1: Write down the positive value in binary
Step 2: Flip the bits ( 1 becomes 0 and 0 becomes 1)
Step 3: Add 1
The more bits for the mantissa, the higher the accuracy
The more bits for the exponent, the bigger the range.
File size (bits) = no of pixels x bit depth
2n ……….
A Memory READ:



The address is put on the address bus
The read line is set on the control bus
The contents of that location are put on the data bus and so
transferred to the CPU.
A Memory WRITE:




The data is put on the data bus
The address is put on the address bus
The write line is set on the control bus
The contents of the data bus go into that storage location
Word Size
Word size = lines on data bus = bits in each storage location
Calculating Potential RAM No of bits = Number of memory locations x num of bits in each
location
No of bits =2ab x word size
J Crooks 15/02/2016
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Calculating the file size of a
digitised audio file
Calculating the file size of a
digital video file
J Crooks 15/02/2016
Filesize (bits) = sampling frequency(Hz) x sample depth(bits) x
length(s) x no of channels
Filesize (bits) = no of pixels x bit depth x frame rate(fps) x
length(s)
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