HART cartridge and the BBGRam cannot coexist because they share
some common I/O registers. Suppose you had HART cartridge
plugged in but not the BBGRam, and you had the HART serial driver
and internal memory driver installed. Then, you decide to unplug
the HART and put the BBGRam in. You do so, then load up
Novaterm again. It locks up! This is because Novaterm is still
loading the HART driver as specified in the configuration file. When it
loads the HART driver, the function that tests for the presence of the
cartridge interferes with the BBGRam, and the system locks up (or
does something else unpredictable). To avoid these conflicts:

1. Unplug everything.
2. Load up Novaterm.
3. Change drivers and save the configuration. (Novaterm will not
    lock up if a device it is looking for simply isn't present.)
4. Plug in the new hardware.
5. Start Novaterm again.

As you get used to switching things around, you'll eventually
determine which cross-configured drivers won't lock up the system.
The I/O registers used by common serial and memory devices are
listed below. A device doesn't necessarily use all registers it reserves,
but it occupies more address space due to "mirroring" of registers.

Memory drivers

internal: No I/O registers used.
VDC+internal: Uses $D600-$D601.
REU: Uses $DF00-$DF0A, mirrored every 32 bytes.
BBG/GEORam: Uses $DE00-$DEFF and $DF80-$DFFF.
RAMLink: Uses $DE00-$DEFF and $DF10-$DFFF.
RAMDrive: Uses $DE00-$DEFF and $DF10-$DFFF.

Serial drivers

User port: CIA #2 registers used.
UP9600: CIA #1 and #2 registers used.
SwiftLink: Uses $DE00-$DEFF ($DE00-0F with AddressFixer).
CommPort: Uses $DF00-$DFFF ($DF00-0F with AddressFixer).
SL-DE20: Uses $DE20-$DE2F (with AddressFixer).
SL-DF20: Uses $DF20-$DF2F (with AddressFixer).
SL-D700: Uses $D700-$D7FF ($D700-0F with AddressFixer).
HART: Uses $DE18-$DE1F and $DF18-$DF1F.