| ??? 08/18/05 06:48 Modified: 08/18/05 06:58 Read: times |
#99618 - Ex[plain A bit more please Responding to: ???'s previous message |
Oleg Sergeev said:
movx @dptr,a ;store byte to destination movx a,@dptr ;readback byte from RAMwith this: Dear Oleg, isnt it that these instuctions reside in the internal program space. AT89c51 accesses ext mem only if 1. PC has a value greater than 1FFFh 2. EA is enabled(not the case here) as the movx instruction is within the 1FFFh its just a internal fetch and on execution access is EXT data access. where !PSEN comes into picture.only !RD/!WR will be issued. the known danger is of bus contention when instructions and data comming from same SRAM. Abhishek |
| Topic | Author | Date |
| week puzzle III | 01/01/70 00:00 | |
| Not getting into details... | 01/01/70 00:00 | |
| you do | 01/01/70 00:00 | |
| see this | 01/01/70 00:00 | |
| Well. . . | 01/01/70 00:00 | |
| let me try | 01/01/70 00:00 | |
| eh? | 01/01/70 00:00 | |
| I`m confused with A15 | 01/01/70 00:00 | |
| Whooops | 01/01/70 00:00 | |
| and I thought that was "the puzzle" | 01/01/70 00:00 | |
| sorry | 01/01/70 00:00 | |
| and I thought that was "the puzzle" | 01/01/70 00:00 | |
| another trouble | 01/01/70 00:00 | |
| And what's wrong with /CS? | 01/01/70 00:00 | |
| sorry, my mistake | 01/01/70 00:00 | |
| what does not happend? | 01/01/70 00:00 | |
| And...? | 01/01/70 00:00 | |
| explain | 01/01/70 00:00 | |
| And...? | 01/01/70 00:00 | |
| Answer for puzzle | 01/01/70 00:00 | |
| I doubt? | 01/01/70 00:00 | |
| I doubt | 01/01/70 00:00 | |
| I agree here | 01/01/70 00:00 | |
| I wonder | 01/01/70 00:00 | |
| autodetect | 01/01/70 00:00 | |
| /PSEN | 01/01/70 00:00 | |
| there is also flaw in the reasoning | 01/01/70 00:00 | |
| Lost inverter | 01/01/70 00:00 | |
| errta | 01/01/70 00:00 | |
| Questions | 01/01/70 00:00 | |
| answers to questions | 01/01/70 00:00 | |
| Timings | 01/01/70 00:00 | |
| Ex[plain A bit more please | 01/01/70 00:00 | |
| intel app note says | 01/01/70 00:00 | |
| I do | 01/01/70 00:00 | |
| re:EA | 01/01/70 00:00 | |
| yes no doubt about it | 01/01/70 00:00 | |
| reset device | 01/01/70 00:00 | |
| three legged | 01/01/70 00:00 | |
The solution | 01/01/70 00:00 |