System Clock, clock speed, Word Length & Bus Width
System Clock, clock speed, Word Length & Bus Width
System Clock
A quartz controlled oscillator that supplies a timing signal at a fixed rate. It could be likened to someone clicking their fingers, everything happens at this rate.
Every computer has its own systems clock.
System Clock, clock speed, Word Length & Bus Width
System Clock
The data and instructions are fetched, decoded and executed in time with the system clock.
Instructions and data are processed in time to the system clock.
Instruction Data Data Instruction Data
1 Hz 2 Hz 3 Hz 4 Hz 5 Hz
A typical clock speed or clock frequency: 2.4 GHz
(2400,000,000 cycles per second)
Clock speed of the processor
System Clock, clock speed, Word Length & Bus Width
System ClockInstructions and data are processed in time to the system clock.
Instruction Data Data Instruction Data
1 Hz 2 Hz 3 Hz 4 Hz 5 Hz
2.4 GHz(2400,000,000 cycles per second)Processor
Internal Bus
MemoryWhen transferring data or instructions between the processor and main memory, sometimes the internal bus speed slows a computer down.
System Clock, clock speed, Word Length & Bus Width
Word LengthData is transferred in binary words. These represent the data and instructions in a computer system.
1 0 1 0 1 0 1 0(x8 bit binary word)
Internal Bus
Word Length
1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0
1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0(x16 bit binary word)
(x24 bit binary word)
W
System Clock, clock speed, Word Length & Bus Width
Bus WidthBus width refers to the number of signal wires or lines allocated to a bus.
Direction of travel
The number of lines in a bus
What is the effect of bus width on binary word size?
System Clock, clock speed, Word Length & Bus Width
Bus Width The effect of bus width on word size
No. Of wires in bus
No. Of bits in a word on the bus
No. Of different binary words
No. Of different binary words as a power of 2
Example of a binary word on the bus
The largest word counting in denary
1 1 2 21 1 1
2 2 4 22 10 3
3 3 8 23 101 7
4 4 16 24 1100 15
8 8 256 28 11110001 255
16 16 65,536 216 1101101111110000
65,353
20 20 1,048,576 220 ... 1,048,575
24 24 16,777,216 224 ... 16,777,215