Yes, I agree working without internet connection is really difficult.
Glad to know you have idea for managing the 64KB of ram efficiently.
I will need to read some doc to understand the memory, the IO subsystem, and how the two cpu communicate it will be the hard part for me because when I work with multiple processor and numa node, it is handled by linux for me.
So lot of thing to understand
Hope you will have your internet access soon.
Yes the z80 and 68k intercommunication is confusing. Last time I wrote this tracker, I never did any work on the z80. Just used bus requests as the 68k requires permission from the z80 to access the YM2612 sound chip, as the YM2612 resides in z80 memory space. This time however the sound driver should be done entirely and purely in z80. The 68k is a 16 bit cpu and YM2612 only accepts 8 bit writes with wait time in between writes, so using the 68k last time was wasteful. Have a look at the sega documentation, it's a must.
Now that I think about it, now would be a good time to start work on the new sound driver, since it's pure z80 I don't need sgdk for this one. By the way. You mentioned you've done x86 asm. 68k is easier and is a gorgeous architecture, it's very logical too. You should have no real trouble understanding it.