How simple...

[Rich M]

>FWIW the rover mini system is a MEMS system... >what ever that means.

"Modular Engine Management System".
In principle the same ECU is fitted to every post-Lucas era 'MEMS'
controlled Rover engined vehicle model (Honda engined versions use Jap
electronics); that includes Mini, 200, 400, 600(turbo only) 800 and MGF.
There obviously need to be variations due to engine spec - capacity, TBI or
multi-point inj., ignition type - distributor or distributorless, turbo or
nat-asp., etc. This is where the 'Modular' bit comes in; the ECU is
fundamentally based on the same internals with various different hardware
configurations and programs to accomodate the different sensors and
actuators required for each individual application.
You will come across a few different 'version' designators; eg. MEMS1.3,
MEMS1.6, MEMS1.9 which   roughly segregate the applications.
All MEMS systems use as a minimum the following sensors:
Crank position
Coolant temperature
MAP
Throttle position
Inlet Air temperature

Additional sensors , depending on application, include:
Knock
Cam position (for Distributorless ignition)
Lambda (post-1992 catalyst vehicles)
Fuel rail temperature

All MEMS systems control ignition, either single coil or distributorless.
All systems use a stepper motor controlled throttle stop for idle speed
control.

Hope this is of interest.
Rich