| ??? 04/30/05 15:20 Read: times |
#92648 - 8051 task switch Responding to: ???'s previous message |
Russell Bull said:
For sure, doing pre-emptive task switching with the 8051 can be limited by the 256 byte stack, but that doesn't preclude you from doing it. Even though Z80 and 6800 are 'real' cpus - they take a few cycles to do a context switch as would a 8051. How much 'real time' does it take a 8051 to save the cpu state to xram? I recently read an article about the development of the 8051 architecture. It said there are four register banks precisely to enable a very fast context switch. The reasoning being that as there are only two interrupt priorities there is never a need to save the context of more than two interrupt routines. The third set of registers is for the backgound task. The forth set is there for the third interrupt priority level you can create as described in the bible. Context switching then becomes no more than pushing PSW and loading PSW to point to your register set. Ian |
| Topic | Author | Date |
| RTOS | 01/01/70 00:00 | |
| The typical tradeoffs.... | 01/01/70 00:00 | |
| OS vs. language | 01/01/70 00:00 | |
| os vs language | 01/01/70 00:00 | |
| OS are used at same place where you use | 01/01/70 00:00 | |
| OS and the '51 | 01/01/70 00:00 | |
| OS and the '51 | 01/01/70 00:00 | |
| 511 pages | 01/01/70 00:00 | |
| URL please | 01/01/70 00:00 | |
| web link | 01/01/70 00:00 | |
| web links | 01/01/70 00:00 | |
| NicheTask != Nucleus | 01/01/70 00:00 | |
| Ok why RTOS? | 01/01/70 00:00 | |
| one strange company | 01/01/70 00:00 | |
| No big kernels for little MCUs | 01/01/70 00:00 | |
| thats nice | 01/01/70 00:00 | |
| OS irrelevant | 01/01/70 00:00 | |
| pllease Explain | 01/01/70 00:00 | |
| re pllease Explain | 01/01/70 00:00 | |
| RTOS when? | 01/01/70 00:00 | |
| not when, but how | 01/01/70 00:00 | |
| Job and Tasks | 01/01/70 00:00 | |
| name one | 01/01/70 00:00 | |
| Example | 01/01/70 00:00 | |
| if you need it | 01/01/70 00:00 | |
| Another Example | 01/01/70 00:00 | |
| an example | 01/01/70 00:00 | |
| Problem with Interrupt priorities | 01/01/70 00:00 | |
| Same priority ? | 01/01/70 00:00 | |
| LOOKS LIKE HOMEWORK!!!!!! | 01/01/70 00:00 | |
| RE LOOKS LIKE HOMEWORK!!!!!! | 01/01/70 00:00 | |
| Dont get angry. | 01/01/70 00:00 | |
| On an 8051 | 01/01/70 00:00 | |
| multicoder | 01/01/70 00:00 | |
| quite likely | 01/01/70 00:00 | |
| Pre-emptive multitasking | 01/01/70 00:00 | |
| RTOS-VxWorks | 01/01/70 00:00 | |
| some posts are off-topic | 01/01/70 00:00 | |
| Not very useful | 01/01/70 00:00 | |
| 'C' is not the only language | 01/01/70 00:00 | |
| U cn us RTlinux and VxWorks | 01/01/70 00:00 | |
| RTOS | 01/01/70 00:00 | |
| honesty | 01/01/70 00:00 | |
| 8 bit RToS | 01/01/70 00:00 | |
| How could I have been so wrong! | 01/01/70 00:00 | |
| Perhaps you practice :)) | 01/01/70 00:00 | |
| Well practiced! | 01/01/70 00:00 | |
| Task Switching Overhead | 01/01/70 00:00 | |
| Has the valve been invented yet? | 01/01/70 00:00 | |
| Tunnel vision | 01/01/70 00:00 | |
| because of tunnel vision | 01/01/70 00:00 | |
| Before PCs | 01/01/70 00:00 | |
| fair? | 01/01/70 00:00 | |
| Sure its fair | 01/01/70 00:00 | |
| Show me the apps | 01/01/70 00:00 | |
| Save your appetite | 01/01/70 00:00 | |
| 8051 task switch | 01/01/70 00:00 | |
| Modern derivatives have 4 priority level | 01/01/70 00:00 | |
| Four banks and context switch | 01/01/70 00:00 | |
| anyway | 01/01/70 00:00 | |
| Lemme see..... | 01/01/70 00:00 | |
| So in fact | 01/01/70 00:00 | |
| What is Real Time | 01/01/70 00:00 | |
| real time | 01/01/70 00:00 | |
| Confused | 01/01/70 00:00 | |
| answers | 01/01/70 00:00 | |
| RE: Answers | 01/01/70 00:00 | |
| extern - intern | 01/01/70 00:00 | |
| Agreed | 01/01/70 00:00 | |
| Why not | 01/01/70 00:00 | |
| Give up | 01/01/70 00:00 | |
| Deifinition of a Poor Engineer | 01/01/70 00:00 | |
| so do I | 01/01/70 00:00 | |
| 8051 RTOS Contract | 01/01/70 00:00 | |
| a real speed demon | 01/01/70 00:00 | |
| RTOS/Multitasking discussed so many time | 01/01/70 00:00 | |
Yes | 01/01/70 00:00 |