| ??? 11/27/06 13:19 Read: times |
#128538 - But why? Responding to: ???'s previous message |
Peter Dannegger said:
because there are pullups inside the µc. I don't think that answers the question! The uC has pullups because it uses negative logic - the question was, "Why negative logic" so with a key against GND no other components needed. Again, that's a consequence of using negative logic - not a reason for using it! If it used positive logic, it would "key" against Vcc - and no other components needed... Or, as in the days of PNP Germanium transistors, call the positive line "GND" and make "Vcc" negative: http://www.8052.com/forum/read.phtml?id=70557 |
| Topic | Author | Date |
| why do we use negative logic in processors&control | 01/01/70 00:00 | |
| Speed | 01/01/70 00:00 | |
| Some previous thoughts | 01/01/70 00:00 | |
| Wire-AND-ing is the remaining benefit | 01/01/70 00:00 | |
| Just imagine ... | 01/01/70 00:00 | |
| ah well... | 01/01/70 00:00 | |
| That would cause one to avoid their devices | 01/01/70 00:00 | |
| because pullup | 01/01/70 00:00 | |
| But why? | 01/01/70 00:00 | |
| TTL outputs | 01/01/70 00:00 | |
| Remarkable advantages when switching to GND | 01/01/70 00:00 | |
| more current | 01/01/70 00:00 | |
| Yes, but why? | 01/01/70 00:00 | |
Physics | 01/01/70 00:00 |