Didaktik 40 and Didaktik 80 is external disk drive interface developed in Didaktik Skalica in former Czechoslovakia. The only difference between model 40 and 80 is the disk drive built in.
Model 40 has 5 1/4 40 tracks 360KB DS DD drive, Model 80 has 5 1/4 80 tracks 720KB DS DD drive.
Second drive can be connected by edge connector at the side. System tests both drives at the startup, so any combination of drives can be connected.
There are two versions of the hardware: V1 uses WD2797 floppy controller chip V2 uses GM82C765B floppy controller chip