If you read further in the thread I linked, you will see that someone dumped the ROM from that Japanese Sega Channel and it somehow boots in emulators. http://forums.sonicretro.org/index.php?showtopic=25935&view=findpost&p=764202 Also, as I said, there are already a few US Sega Channel ROM floating around (although there isn't much to see). You are right that most menu graphics/sounds/text were retrieved from cable network since it was regularely updated but the console needs code with 68k instructions to boot from and initiate the menu routines. It would not make much sense to have that bootcode in volatile RAM, loaded entirely from network everytime you start the console, especially when the boot code does not really need to be changed. It is also very likely that the FPGA does the address decoding when the console accesses the cartridge and has a way to switch between Internal ROM and the RAM where the downloaded game is stored, so it would be normal that address/data/ctrl lines go trough it from cartridge port. I am not sure exactly why you can not dump it with Sega CD method but it might just be that Sega Channel cartridge has hardware mapped in the same range as Sega CD hardware or does full-range address decoding which prevents the cartridge ROM from being accessed through the upper memory area (which becomes cartridge area when the console boots from Sega CD).
I wasn't able to view that page earlier as sonic retro appeared down for maintenance at the time. There's a ton of good info in there, thanks for the link!
This looks very cool. The sega cd method sounds very close to what they did back in the day. You see,back in the day,sega would send cable providers a cd with some roms and some update info for the list of games and news.
You can grab photos of the innards of the Japanese Sega Channel Adapters I dumped here and here. Hope you discover more way past cool things!
I hope so as well, i need to find a tool to dump the ROM. The Sega CD method does not work with the Sega channel. The rom appears to be re branded by scientific Atlanta so i have no clue as to which programmer i need. I may just go with the one used on sonic retro and hope it works both ways.
Just a few notes that may/may not help. If you're going to set it up to broadcast, keep in mind that there were the handful of different models due to different cable companies using a different "cable plant". The Scientific Atlanta(SA) may receive signal differently than the Texas Instruments ones. This is why in the US if you and a friend both have the same provider and live a town apart, he may have a Motorola cable box, and you get an SA one. They can't be swapped between areas, and SA is generally inferior. I work with someone that used to install these, I'll see what info I can get from him on Tuesday if I remember. The one thing I do remember is that he told me he would have to install a filter on the line but I can't remember the specs on it.
