[Coco] ROM Cart registers

[Darren A]

On Sun, Jan 31, 2016 at 12:47 PM, RETRO Innovations <go4retro at go4retro.com>
wrote:

I am struggling to  think of a valid reason to strobe SLENB* when SCS has
> not been strobed and the address is located in the $ff40-$ff8f range.
>
> Jim
>


It means you're claiming the address space for exclusive use and you don't
need to make the effort to write an "MPI aware" driver. You completely
decode addresses yourself so the device is always active, even when the MPI
slot containing it is not. By asserting SLENB* you prevent other devices
(those that require SCS) from responding and creating a conflict,
effectively locking them out.

SCS only covers the $FF40-FF5F range.  $FF60-FF7F were assigned by Radio
Shack to various products. $FF80-$FFDF are allocated to the GIME on the
CoCo 3.

- Darren