| ??? 07/27/05 17:19 Read: times |
#98292 - Seems kind of pointless Responding to: ???'s previous message |
I'm not one to say that just because one needs more than 64k of memory that the 8052 is automatically the wrong choice (though it certainly is possible), but this theoretical "solution" just seems weird to me.
A couple of points struck me from the article. From the article said:
Because of the control A15 has over BS[2..0], the common area is always accessed as the lowest 32KB of the physical memory regardless of which bank is selected by the BS[] pins. Therefore, the lower 32KB of Banks 1 through 7 are unused and unavailable. This is about the most memory-inefficient way I've seen to wire banked memory. Would anyone really develop a circuit where they're throwing away 32k of each 64k of available memory? From the article said:
Then the PME-51 detects that an interrupt is being processed it takes all the actions of a FCALL instruction except that it clears the XAR instead of loading it with the contents of the holding register. The XAR is cleared since all 8051 interrupt vectors reside in the first 64KB of program memory. Right. And how exactly does an external part detect when the 8051 starts executing an interrupt? Or does it just assume that anytime address 0003h, 000Bh, 0013h, etc. are executed that it is automatically an interrupt? José Félix Díaz Ivorra said:
d)How the system detects 'ajmps' from 'fjmps'? Or we loose the ajmp I wondered the same thing. I don't think he explicitly said it, but I assume we lose AJMPs and ACALLs. I don't see the point. Even as a mental exercise I don't see the point. It requires hardware that doesn't exist, software tools that don't exist, and to what end? If it can be said that few 8052 applications require 512k of code memory, I think it can be even more safely said that even fewer require 512k of contiguous code memory. I see nothing wrong with traditional bank switching as long as you don't use the inefficient approach that is suggested in the article. Regards, Craig Steiner |
| Topic | Author | Date |
| "Expand your 8051 memory" | 01/01/70 00:00 | |
| Nice technique used | 01/01/70 00:00 | |
| tour de force | 01/01/70 00:00 | |
Not necessarily... | 01/01/70 00:00 | |
| reinventing a square wheel | 01/01/70 00:00 | |
| Re: Expand your 8051 memory | 01/01/70 00:00 | |
| Hmmm | 01/01/70 00:00 | |
| Pranav! | 01/01/70 00:00 | |
| Very nice dream | 01/01/70 00:00 | |
| Seems kind of pointless | 01/01/70 00:00 | |
| Only a mental exercise | 01/01/70 00:00 |