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| MMC64 + RRnet https://www.retrohackers.org/viewtopic.php?f=6&t=74 |
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| Author: | RaveGuru [ Mon Mar 20, 2006 2:16 am ] |
| Post subject: | MMC64 + RRnet |
I'm trying to get RRnet connected to the MMC64 working. I can access the RRnet but I get intermittent results. I'm writing #$0a, #$1c to $df13 to initialize the MMC64, then I toggle bit 1 in $df11 to read #$64 and Revision# out of $df13, leaving bit 1 in $df11 enabled. Finally I'm clearing bit 3 in $df11 to put clockport IO at $de00. I don't know if this is the correct register settings for transparent clockport access, but the documentation is sparse. What exactly does bit 1 in $df11 ("card selected") imply by the way? |
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| Author: | tnt/beyond force [ Mon Mar 20, 2006 9:52 am ] |
| Post subject: | |
Can't help with RR-net, but "card select" controls /CS line for MMC/SD card. It needs to be 0 for the card to respond to commands. It's also used to synchronize SPI bytes - toggling it before commands helps with some cards. |
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| Author: | RaveGuru [ Mon Mar 20, 2006 6:35 pm ] |
| Post subject: | |
Hmm.. so it shouldn't interfere with the clockport access then. How exactly does bit 0 and 5 in $df11 correlate? |
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| Author: | tnt/beyond force [ Mon Mar 27, 2006 12:44 pm ] |
| Post subject: | |
RaveGuru wrote: How exactly does bit 0 and 5 in $df11 correlate?
Code: Bits config
0 5 ------------------------- 0 0 : $8000 = MMC64 BIOS 0 1 : $8000 = MMC64 BIOS 1 0 : $8000/$E000 = external ROM if any, depending on cartridge 1 1 : $8000 = RAM, $E000 = kernal I don't remember if bit5=1 also disables cartridge I/O lines, but that would be logical (assuming Oliver had enough I/O pins available). |
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| Author: | RaveGuru [ Tue Mar 28, 2006 9:51 pm ] |
| Post subject: | |
Ok. Just borrowed a MMC64 so I'll check it out ... |
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| Author: | RaveGuru [ Wed Mar 29, 2006 6:17 pm ] |
| Post subject: | |
I emailed Jens Schoenfeld and got a pretty interesting answer back. Jens Schoenfeld wrote: Many C128
computers have serious timing problems that I haven't been able to solve with the MMC64 yet. The Retro Replay works fine because it uses a much older (and slower) logic chip. The ultrafast logic chip on the MMC64 is "too fast" for a few C128 models. Sometimes it helps to re-install the metal shield in the C128 (many people remove that), this reduces GND noise. Further, the clockport is re-mapped to $de20 if a Retro Replay is detected in the pass-through port of the MMC64. It's all relevant information, however since I'm on a C64 this is probably not related to my problem. I've emailed back and currently waiting for response. I'll keep you posted. |
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