Here's a small collection of information regarding the Rover Engine Management Unit (ECU) .
The Rover Modular Engine Management System (MEMS) does exist since the early 90s. For the early SPI (Single Point Injection) Models the MEMS 1.3 and MEMS 1.6 has been used. Later for the MPI (Multi Point Injection) Models the MEMS 1.9 and MEMS 2J replaced the early versions.
As sucessor of the classic MEMS the MEMS 3, was introduced later, however this was based on a complete new development and design.
At www.rovermems.com you'll find a great collection of Information about all MEMS 1.3 up to MEMS 2J. James Portman has done an impressive Job and offers all necessary Hard- & Software for perfoming necessary Diagnosis.
Andrew Revill has been busy on the MEMS 3 angenommen and offers software for re-programming and diagnosis!
It might be worth to mention, that the trigger pattern is different between the MEMS Versions. Below you can find the patterns in an overview. A "00" represents a gap, a "01" a tooth on the trigger wheel.