The C64 Floppy-Speeder Professional-DOS from Mikrotronic

"The Professional-DOS Floppy-Speeder from Mikrotronic for the Commodore home computers C64, C128 and C128D and it's peripherals C1541, C1541-C and C1571 was one of the Super-Floppy-Speeders. This class of speeder systems were mostly equipped with hardware modification boards and a parallel cable of course. Well known products are Dolphin-DOS from Dolphin-Software, Prologic-DOS (Classic) from Jann Datentechnik, Turbo-Trans from Roßmöller and Professional-DOS from Mikrotronic."