| ??? 04/17/02 08:49 Read: times |
#21852 - RE: Read-write signals |
Hi Phillip, Charles,
why to the hell PSEN was connected ? PSEN was only needed, if code want to be executed from SRAM. And then it must be ANDed with /RD. On memory mapped I/O or SRAM as data space only, /RD and /WR must be used but never PSEN ! Instead 8255 I use simple 74HC541 / 74HC573 as I/O and then the 74HC139 as decoder. Then on one half of the 74HC139 the /WR signal can be included to drive the 74HC573 latches. Peter |
| Topic | Author | Date |
| Read-write signals | 01/01/70 00:00 | |
| RE: Read-write signals | 01/01/70 00:00 | |
| RE: Read-write signals | 01/01/70 00:00 | |
| RE: Read-write signals | 01/01/70 00:00 | |
| RE: Read-write signals | 01/01/70 00:00 | |
| RE: Read-write signals | 01/01/70 00:00 | |
| RE: Read-write signals | 01/01/70 00:00 | |
| RE: Read-write signals | 01/01/70 00:00 | |
| RE: Read-write signals | 01/01/70 00:00 | |
| RE: Read-write signals | 01/01/70 00:00 | |
| RE: Read-write signals | 01/01/70 00:00 | |
| RE: Read-write signals | 01/01/70 00:00 | |
| RE: Read-write signals | 01/01/70 00:00 | |
| RE: Read-write signals | 01/01/70 00:00 | |
| RE: Read-write signals | 01/01/70 00:00 | |
| RE: Read-write signals | 01/01/70 00:00 | |
| RE: Read-write signals | 01/01/70 00:00 | |
| RE: Read-write signals | 01/01/70 00:00 | |
| RE: Read-write signals | 01/01/70 00:00 | |
| RE: Read-write signals | 01/01/70 00:00 | |
| RE: Read-write signals | 01/01/70 00:00 | |
RE: Read-write signals | 01/01/70 00:00 |