The NSC driver installer starts off by checking each slot, bit-banging
into the card's memory space to try and detect an NSC installed. If a
Z80 card is encountered before the NSC is hit, the Z80 card is
activated, causing the 6502 to halt.
Borrow the Z80 detection routine from A2D's This Apple and verify that
there isn't a Z80 in the slot before we start bit-banging.
Fixes#15
When a SmartPort device was found that wasn't the FujiNet, the search
continuation used the wrong offset to get the high byte of the slot
address.
Also, fix the "jumbo" clock driver's Makefile to ensure it is rebuilt
when dependencies change.
This one driver pulls in the installers for each other clock driver,
and invokes each in turn:
* No-Slot Clock
* ROMX
* FujiNet
* DClock
* Cricket!
This requires adding `.ifndef JUMBO` guards in the other drivers for
when they pull in include files (symbols, macros, etc). The other
drivers are adjusted to return with carry clear on successful install,
failure otherwise.
