The Sentinel 65X memory map:
- In 65C02 emulation mode:
$0000-7FFF: RAM
$8000-DEFF: ROM
$DF00-DFFF: I/O
$E000-FFFF: ROM
- In Native mode:
$000000-007FFF: RAM
$008000-00DEFF: ROM
$00DF00-00DFFF: I/O
$00E000-00FFFF: ROM
$010000-07FFFF: RAM
$080000-BFFFFF: Reserved for expansions
$C00000-C7FFFF: ROM
$C80000-FFFFFF: Reserved for expansions
In both modes, you can disable the ROM in the low 64K for more RAM by clearing bit 4 of $00DF27.
If you do bank out the ROM, you should copy the interrupt vectors starting at $00FF80 to RAM, or disable interrupts. Up to you.
The CPU technically starts up in 6502 emulation mode, but by the time any user facing code is running, it's already in 16-bit native mode.
You can control the procesor speed with the bits of $00DF4, the system speed control register; you can choose 8MHz or 2MHz operation. Most likely 2MHz is only useful to talk to very slow expansions.
You will note that the top four bits affect the CPU speed when the current address is in a particular memory region, while bit 3 sets the "default" speed. If you happen to clear bit 1, then you will be running the CPU off the 32KHz TOD clock signal -- I cannot imagine a productive use for this, but I can't stop you.
