Clock Source
- 8051 operates based on an external crystal.
- The Most common crystal frequency is 11.059 megahertz
- 8051 use crystal to synchronize operations
- Crystal generate and feed clock pulses to 8051
- 11.059 megahertz crystal pulses 11,059,000 times per second
- 12 pulses constitute a machine cycle
- A machine cycle is the minimum amount of time in which a single 8051 instruction can be executed.
- Instruction cycle (Fetch, Decode, Execute): 11,059,000 / 12 = 921,583
- 8051 can execute 921,583 single cycle instructions per second.
- 8051 can execute 460,791 two cycle instructions per second.
- 8051 can execute 230,395 four cycle instructions per second.
- Not all instruction execute in the same amount of time. Fastest one requires 1 machine cycle (12 crystal pulses), some other requires 2 machine cycle (24 crystal pulses) and slowest requires 4 machine cycle (48 crystal pulses).
- There are optimized versions of 8051which executes instruction much faster than standard 8051.
Related topics:
8051 Instruction Set Overview | 8051 Instruction Cycle | 8051 Instruction Set Summary | 8051 Arithmetic Operation Instructions | 8051 Logical Operation Instructions | 8051 Data Transfer Instructions | 8051 Boolean Variable Manipulation Instructions | 8051 Program Branching Instructions | 8051 Instruction Opcode | 8051 Instructions that Affect Flag Settings | 8051 Instructions and Examples
List of topics: 8051
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