| ??? 04/21/07 14:02 Read: times |
#137712 - 8051 operation Responding to: ???'s previous message |
1. How is the machine cycle of a processor(for 8051 its 12 clock cycles) calculated? See its same for all 8051 family members though they are designed by different logics- CMOS,LS,HSMOS.... There are many different types of 8051. The original had 12 clocks per machine cycle. Some modern ones have only one. Which 8051 are you talking about? 2. Instruction cycle in 8051 is a combination of how many and what cycles(read cycle, write cycle, fetch cycle.....)? Again, it depends on which 8051 you are talking about. In the original 8051, every two oscillator clocks produced a single internal clock. Any read from ROM took 3 of these internal clocks. There was always a fetch read, and an operand read, even if there was no operand to read. Some instructions required a third read for a second operand. RAM and register operations took one internal clock cycle. 3. Data sheets say that 8051 has an internal oscillator then why do we need a crystal oscillator for 8051(connected to 18,19 pins)? |
| Topic | Author | Date |
| Strange Questions on 8051 | 01/01/70 00:00 | |
| 8051 operation | 01/01/70 00:00 | |
mix of terminology | 01/01/70 00:00 |