Semi-Automatic simply means that there is no clutch but there is a gear shift lever through which you need to change gears. There are two speed ranges, one for the low speed i.e. upto a max. of 80kph and normal drive mode i.e. upto a max. of 120kph.
So, you don't require to push clutch while shifting gears but you still need to pull the lever to 'D' mode if you are on highway. In fully automatic cars, a controller does shifting automatically. This TCU (Transmission Control Unit) can be installed in mehran too but I haven't found it yet.
I hope your question has been answered well.