A flow-based FIFO sub-system for a disk formatter in a data processing system that performs data width conversion. The sub-system has a first FIFO unit having a first width interfacing to a first bursting channel, and a second FIFO unit having a second width interfacing to a second bursting channel, the second width not being a multiple of the first width and the first width not being a multiple of the second width. Data width conversion is performed between the first FIFO unit and the second FIFO unit to convert data moving from the first FIFO unit to the second FIFO unit from the first width to the second width, and to convert data moving from the second FIFO unit to the first FIFO unit from the second width to the first width. The sub-system also includes an Error Correcting Code interface between the first FIFO unit and the second FIFO unit for performing in-line correction.