| ??? 04/02/07 23:44 Read: times |
#136455 - Eureka! Responding to: ???'s previous message |
With /EA high, and if you have less than 64K of program storage, then the MOVC instruction will be internal for the internal code, and external for the external code. Wow, that's very interesting! So just to make sure I understand this correctly: When running from internal code (/EA high as you said) once the PC is outside of the internal memory area (say $0000-$1FFF for a 8K ROM) then the remaining 56K of the program address space is treated as external? Meaning /PSEN will be strobed for each opcode/operand fetched within $2000-$FFFF? I had assumed the program ROM was mirrored beyond that point or it was just unusable space, but that's wasteful. In the context of how the security bits work, this certainly makes a lot of sense. |
| Topic | Author | Date |
| MOVC question | 01/01/70 00:00 | |
| what derivative? | 01/01/70 00:00 | |
| Re: MOVC question | 01/01/70 00:00 | |
| MOVC is external with /EA low | 01/01/70 00:00 | |
| Eureka! | 01/01/70 00:00 | |
| You are correct | 01/01/70 00:00 | |
| Derivative dependent | 01/01/70 00:00 | |
| I'm a classical sort of guy | 01/01/70 00:00 | |
| I think it is irrelevant to discuss derivatives... | 01/01/70 00:00 | |
| not discussing such | 01/01/70 00:00 | |
| for example DS89C4x0? | 01/01/70 00:00 | |
| yup | 01/01/70 00:00 | |
| Blast from the past | 01/01/70 00:00 | |
| this is how it works with an unlocked AT89C52 | 01/01/70 00:00 | |
| Nice work | 01/01/70 00:00 | |
miniLA | 01/01/70 00:00 | |
| an answer | 01/01/70 00:00 |