On 3/9/2012 3:52 PM, Gábor Lénárt wrote: > Well, yes that's the uC part which is even more "alien" for me :) For > example I am not sure an average uC (like what you mentioned above) > has enough speed to serve an interrupt triggered by eg the PC (low > level active, afaik, but maybe it should be triggerd by the falling > edge instead?) line from C64; since I plan to use interrupts on the uC > part, so the uC itself can do other things meanwhile in the "main > program" (not in interrupt handler). Anyway, never mind, I will also > ask my "uC expert friend here" before I write too much non-senses here > :) It's really interesting on the DTV though where I guess even > 1Mbyte/sec is possible with DTV's DMA but then anyway since lack of > the handshaking, no interrupt service is needed but some kind of very > exact timing instead (or using somewhat slower "manual" method to > "ack" every bytes). AVR's can be triggered on rise, fall, high level, or low level. I think, for now, ignore DMA. As you note, you'll need some way to sync, which complicates things. If you don't use DMA, you have more time to process a read/write (unless you're running a SuperCPU or Chameleon whic can issue IO at 1MHz) > Well, I'm more used to have von Neumann architecture rather than Harvard :) > Isn't it possible to use normal RAM for code with eg an AVR (maybe even > internal RAM, I guess it's possible to use external RAM with uCs with > external bus interface but it implies a rather pin-monster being, hehe)? THere are some that can do that, but not the AVR. As far as I know, PIC and AVR must run apps from FLASH, not RAM. > So the flash would only contain the boot loader itself. But anyway a simple > theory: I can store eg a word in my firmware which mean some kind of > "version number". The boot loader can check the version number from the SD > card and the version number flashed by the boot last time. If they are the > same, no re-flashing is needed. Or maybe even some kind of checksumming > which is more accurate stuff. Other possibility is to have a simple button > I have to hold while powering-on the require loading (and flashing into the > uC) a new firmware. Yep. Message was sent through the cbm-hackers mailing listReceived on 2012-03-10 05:00:05
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