Issue:
I am running Mkdev serial using driver version 1.x and the following is shown: 
AT-FAST       I/O   100
AT-FAST5     I/O   180
What selection should I use and what is AT-FAST5?

Solution:
The AT-FAST 5 selection is a valid selection, like the AT-FAST, if required. Due to the AT-FAST 16 port only supporting 5 signals the AT-FAST 5 is for 5 signals only. The AT-FAST is for 8 signals, which was not implemented on the 16 port card, but can be selected and use with 5 signals.