3. How to measure a computer system

How to measure a computer system

The processor speed refers to how fast executions can be performed within a computer, the frequency is measured in Hertz. The memory size refers to how much data can be stored, the size is measured in Bytes as data is stored in binary format.

SI Prefixes

Prefix	Symbol	Value	Power
tera-	T	$1,000,000,000,000$	$10^{12}$
giga-	G	$1,000,000,000$	$10^9$
mega-	M	$1,000,000$	$10^6$
kilo-	K	$1,000$	$10^3$

Prefix	Symbol	Value	Power
milli-	m	$0.001$	$10^{-3}$
micro-	$\text{micro}$	$0.000001$	$10^{-6}$
nano-	n	$0.000000001$	$10^{-9}$
pico-	p	$0.000000000001$	$10^{-12}$

Powers of 2

Typically, memory is given using SI prefixes but it is more accurate to measure memory in powers of 2 instead of powers of 10.

An additional i is used to represent powers of 2, e.g. 7895 MiB.

Prefix	Symbol	Value	Power
tebi-	Ti	$1,099,511,627,776$	$2^{10\times 4}$
gibi-	Gi	$1,073,741,824$	$2^{10\times 3}$
mebi-	Mi	$1,048,576$	$2^{10\times 2}$
kibi-	Ki	$1,024$	$2^{10\times 1}$

Hence, $7985\text{ MiB}=7895\times 2^{10\times 2}\text{ B}=7,953,448,960\text{ B}$.

For this course, we stick to SI prefixes.