Timeline for What are my options for fast bidirectional transfer between a C64 and a 1541?
Current License: CC BY-SA 4.0
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| Mar 10, 2020 at 2:21 | comment | added | Tommy | @Raffzahn right; I started with code that is designed for the display off to see how fast you can go if you don't have to worry about bad lines and sprite fetches, then calculated it out for 40 bytes to see whether it would fit in the vertical area where there are no sprites or bad lines. And I think it fits, though I showed my arithmetic in case I've made a calculation or logical error. | |
| Mar 9, 2020 at 22:52 | comment | added | Brian H | Good answer. Installing standard JiffyDOS into the C64 and drive would probably be the first thing I'd try. If both drive and host lose max. 25% to the transfer overhead, and the host can do it without being affected by any interrupts or VIC-II bad lines, then seems pretty predictable to work within those constraints for the rest of the 75% per frame available on both CPUs. Plus you have VBLANK time. Trouble is figuring out how to have user code coexist nicely with JiffyDOS code, which I'm sure uses some of the 2kB in the 1541. Who knows? It might even suck up the whole zero page. | |
| Mar 9, 2020 at 21:52 | comment | added | Raffzahn | As far as I understand it the question is about data transfer with display not only enabled, but updated by the data received as well. | |
| Mar 9, 2020 at 21:32 | history | answered | Tommy | CC BY-SA 4.0 |