These are less expensive drives and were meant to be directly connected as B drive to a CPC 464 with DDI-1 or a CPC 664/6128. Since these drives ship neither with an own controller nor a [[VDOS]] ROM, they do rely fully on AMSDOS and thus only 40 tracks on one side can be accessed, resulting in the same capacity (180K/side) as the 3" drives. Technically, the Z-drives are actually only S-drives without Vortex controller and CP/M licence.
The 5.25" drive used in the F1-Z drive is based on a later revision of the BASF 6138 (81757-001)drive, which offers more configuration options using jumpers. The drive was shipped with a setting of 40 tracks, and thus the cheaper DS DD floppy disks (48 tpi, 180K/side) could be used.
=== Variants ===