| ??? 03/18/05 10:01 Modified: 03/18/05 10:06 Read: times |
#89917 - xor Responding to: ???'s previous message |
/ROM_CS = control_pin .XOR. A15
/RAM_CS = .NOT. /ROM_CS /RAM_WR = /WR /RAM_OE = /RD /ROM_OE = /PSEN I wonder how do you want to control the control_pin. If you switch while running program from ROM, if you don't do it exactly at the boundary (7FFF-8000 when switching ROM from 0-7FFF to 8000-FFFF and FFFF-0 when switching back (but at 0 you have the reset vector, so you need also to distinguish between reset and fall-through)), it will crash. (for both data and code space /RAM_OE = /RD .AND. /PSEN /ROM_OE = /RAM_RD) More variations possible, please specify why you want to do this. Jan Waclawek |
| Topic | Author | Date |
| Interfacing to EPROM/RAM | 01/01/70 00:00 | |
| Yes you can...but | 01/01/70 00:00 | |
| do some reading on how the 8051 works | 01/01/70 00:00 | |
| exact hardware | 01/01/70 00:00 | |
| Yes but.... | 01/01/70 00:00 | |
| its mentioned | 01/01/70 00:00 | |
| Actually it isn't | 01/01/70 00:00 | |
| sorry for that | 01/01/70 00:00 | |
| xor | 01/01/70 00:00 | |
| truth table | 01/01/70 00:00 | |
solution | 01/01/70 00:00 |