Vortex Disc Drives

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A series of external 3.5" and 5.25" floppy disc drives from Vortex providing up to 720K capacity (704K available). The Vortex drives were most popular in Germany. For more information regarding VDOS and the Vortex Disk Format, see the dedicated VDOS Wiki page.

S- and D-Drives (720K)

These are the first generation of 720K floppy disc drives from Vortex. They came in variants having either a single drive ("S" variant) or two drives ("D" variant). The "S" variant (as well as the less expensive "Z" variant) was delivered with the same double-height casing as the "D" variant, so that a second drive could be retrofitted.

F1-S and F1-D (5,25")

The F1-S and F1-D models are based on BASF 6138 (81690-001) type 5,25" disk drives, i.e. double-sided, 80 tracks per side, 96 tpi density.

M1-S and M1-D (3,5")

The M1-S and M1-D models are based on 3,5" disk drives.

A1-S Upgrade Kit

Vortex offered an upgrade kit consisting of a single bare drive and an installation manual, allowing to upgrade a single F1/M1-S drive to a dual F1/M1-D drive. To do this, one simply had to install the additional drive in the free slot of the drive case.

FDA-1 3" Drive Adapter

This adapter makes it possible to connect an external FD-1 3" drive on Vortex F1/M1 setups on the CPC 464. Since only two drives can be used at the same time, the external 3" drive first had to be selected manually with RSX commands.

RSX Description
|S,1 Use 3" drive as drive A, upper Vortex drive is disabled
|S,2 Use 3" drive as drive B, lower Vortex drive is disabled
|S,0 Disable the 3" drive (default)

FDC I/O Ports

All types of floppy disk controllers for the F1-S/D and M1-S/D series are based on the NEC 765 chip. The manual states that on "controllers having an integrated ROM module/eprommer" (probably the later 6128 interfaces?), the port addresses can be freely configured using a decoder ROM.

CPC 464:

Address Description
0xFB7E uPD control
0xFB7F uPD data
0xFA7E motor on/off

CPC 664/6128:

Address Description
0xFBF6 uPD control
0xFBF7 uPD data
0xFA7E motor on/off


Z-Drives (180K/side)

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.

F1-Z (5,25")

The F1-Z model is based on a later revision of the BASF 6138 type disk drive (81757-001), which offers more configuration options using jumpers. The drive was shipped in a "double step" configuration to use only 40 tracks, and thus the cheaper and more widely available DS DD floppy disks (48 tpi, 180K/side) could be used.

M1-Z (3,5")

The M1-Z model is equipped with a single 3,5" disk drive.

A1-Z Upgrade Kit

Vortex offered an upgrade kit consisting of a controller, manual, CP/M license and an utility disk which allows a Z-Drive to be upgraded to a S-Drive.

X-Drives (720K)

These are the latest drives from Vortex for use with a CPC 464 with DDI-1 or a CPC 664/6128 (ie. on systems that already have a floppy disc controller); no additional controller was required anymore. Instead, a ROM module was supplied together with the drive, which provided VDOS 2.0-X. Only single-drive variants were available. The |S command (for accessing a third drive) is no longer used, the new |X command allows to swap drive A and B (same as X-DDOS from Dobbertin).

F1-X and F1-XRS (5,25")

The F1-X model is based on a single BASF 6139 type 5,25" disk drive. These are compatible with the BASF 6138 disk drives used in the previous 5,25" models, but have a slightly more compact design and a number of design flaws that affected durability were corrected. The F1-XRS variant is equipped with an additional RS232-C interface.

M1-X and M1-XRS (3,5")

The M1-X model is based on a single NEC FD1035 type 3,5" disk drive. The M1-XRS variant is equipped with an additional RS232-C interface.


The X-drives for the CPC 664/6128 are connected directly to the floppy port. In order to provide VDOS, the "X-Modul" (sometimes also called "VDOS module") must be connected additionally to the expansion port. This contains a ROM board that provides a VDOS 2.0-X ROM. The ROM board supplied for the CPC 464 came together with a chunky housing in which both the "X-Modul" and the DDI-1 controller were installed. All variants were also available with an additional RS232-C interface (in this case called either "XRS-Modul" or "X-Modul/RS").

RS232 I/O Ports

The RS232-C interface of the "XRS-Modul" was advertised to be compatible with Amstrad/Pace interfaces, but offers only one channel (so no channel B).

Address Description
0xFADC SIO data (R/W)
0xFADD SIO control (R/W)
0xFBDC 8253 counter 0 (R/W)
0xFBDD 8253 counter 1 (R/W)
0xFBDF Mode word (W)