What is the mark IV and mark V control system of GE gas turbine? Briefly explain it? And how it works?

Dear Khalid Abdur Rehman, The Mark V and Mark VI is two version of speedtronic turbine control system from GE (general electric) ,this system does control all functions of a gas turbine or steam turbine (alsoto protect the turbine against the over-temperature and over-speed ...)

The Mark V and Mark VI including TCP (turbine control panel) with industrial controller (one in simplex and3 controllers in TMR type) and different I/O card, terminal board...This system also consists of their own software (EX: TOOLBOX, Cimplicity in HMI)..

Mark v , vi and vie plc based control , these are version for  SPEEDTRONICControl contains a number of control, protection and sequencing systems designed for reliable and safe operation of the gas turbine. 

Markv oldest , markvi new markvie newest 

I understand the funtionalities of Emersson Dcs. How much longer time need to understand Mark V or mark VI system?