| ??? 06/20/05 12:22 Read: times |
#95338 - to slow, too low Responding to: ???'s previous message |
The 8255 is not an 8085/805x/804x compatible device by design, ... may, in fact, be too slow for the MCU in question in the upper reaches of its clock rates.
excellent statement I don't recall whether that MCU allows software controlled extension of the external memory cycle in its memory-mapped application. "the MCU in question ..that MCU" come on, Richard, this is a '51 forum. The '51 architecture does not as standard have memory cycle stretching, however some derivatives (Dallas, SILabs) do, however not in an "address range dependent" way. ...the current-generation of programmable logic tolerates 3 volts, tops, with 5-volt tolerance Lattice, for one, still has a good selection of 5V parts. Erik |
| Topic | Author | Date |
| external memory access problem | 01/01/70 00:00 | |
| my first suggestion.... | 01/01/70 00:00 | |
| actually i tried in single instruction | 01/01/70 00:00 | |
| more | 01/01/70 00:00 | |
| Relic Chips Are Slow | 01/01/70 00:00 | |
| Memory Map IT !! | 01/01/70 00:00 | |
| and then you may get others | 01/01/70 00:00 | |
| Such AS ?? | 01/01/70 00:00 | |
| with the '51 | 01/01/70 00:00 | |
| 8085/805x <=>8255 | 01/01/70 00:00 | |
| to slow, too low | 01/01/70 00:00 | |
really need more info to be helpful | 01/01/70 00:00 | |
| Query | 01/01/70 00:00 | |
| re query | 01/01/70 00:00 |