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 a 5¼″ 40-track 360KB DS DD drive, whereas model 80 has a 5¼″ 80-track 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
The interface contains the PPI i8255 chip. All of its ports are routed to edge connector at side and the system doesn't use it, so it's available for user's I/O fully. It can be enbled/disabled by the OUT instruction. It is because there are Spectrum clones with 8255 included at the same ports. It is in socket always, so it can be removed or replaced easily in the case of troubles.