Disk drives

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The Floppy Disk Drive is a common Mass Data storage from the 80's.

Alongside other technologies :

In modern day, the Cassette port can easily be replaced by any modern audio device : MP3 or CD readers.

  • Amstrad CPC464: This computer lacks the disc controller hardware and the software to use a disc drive. To use discs on an Amstrad CPC464 the most compatible interface is the DDI-1 (this includes AMSDOS ROM). Normally this interface came with one FD-1 3" disc drive.
  • Amstrad 464+: This computer lacks the disc controller hardware and the software to use a disc drive. The PCB of the 464+ is the same as the 6128+ but with the components removed. So it is possible to add all the extra components required to get a disc interface and Amstrad Action published an article about how to do this. However finding all the components is not so easy now. A DDI-1 can be fitted to the 464+, but you will probably need a conversion cable; to convert the connector on the expansion to the old edge connector on the DDI-1, but also the DDI-1 interface needs modifying to be compatible.
  • Amstrad CPC664, CPC6128, 6128+: These computers all come with disc interface and AMSDOS ROM integrated into the computer. In addition they all come with an internal 3" disc drive.

Disks are one of the easiest way to use programs on the Amstrad.

The 3" drives and 3" discs are not so easy to find now.

For many years now, most users connect a 3.5" disc drive.

Mostly this drive is connected as external drive B (and potentially with a drive switch to swap roles of drive A and drive B).

Some Amstrads have been customised to fit one internally, but this does require modifying the case and is easier on a 6128+.

Technical Information

Characteristics of a disc drive:

  • Number of sides
  • Number of tracks
  • Rotational speed
  • Ready signal
  • Density of the media it can read
  • Disc format
  • Capacity

Number of Sides

Number of sides is 1 (single sided) or 2 (double sided).

The number of sides determines the total capacity that this drive can access.

AMSDOS & Double sided drives

AMSDOS is designed for single sided drives. This means it will only read 1 side of a double sided disc. The standard AMSDOS format is 178K per side.

For 5.25" drives:

  • You can cut another write-protect notch on the other side. Then you can turn the disc over and insert it the other way up. With standard AMSDOS format you now have 2 * 178K for each disc.

For both drives:

  • Use another DOS on CPC, one which can read/write 2 sided discs (ParaDOS, ROMDOS etc). The disc formats supported by the other DOS each have their own capacity.
  • Install a side switch. This gives you manual control over which side is accessed. With standard AMSDOS format you now have 2 * 178K for each disc.

Number of Tracks

Number of tracks is either 40 or 80.

The number of tracks determine the total capacity that this drive can access.

NOTE: It is possible to read a disc created on a 40 track drive in an 80 track drive.

AMSDOS and number of tracks

All the default formats are designed for 40 track disc capacity.

DATA format is 178K per side.

If you have an 80 track drive and you want to use it's capacity you need to use another CPC DOS that can use 80 tracks.

Rotational Speed

The rotational speed is either 300rpm or 360rpm, and it is the speed at which the disc is rotated within the drive when the motor is active. The speed of the motor doesn't affect data transfer rate.

Ready signal

The CPC floppy disc controller requires a "ready" signal from the drive.

The drive is ready when:

  • the disc motor is on,
  • the drive is selected
  • a disc is in the drive
  • the rotational speed has stabalised (a short time after motor is switched on)

Density of the media it can read

The drive is designed for one or more specific media densities which it can read.

Low density (FM), Double Density (MFM), High Density (MFM).

Examples of low-density:

  • BBC Micro DFS formatted discs.

Examples of double density:

  • 360K 5.25" PC MS-DOS formatted discs
  • 720K 3.5" PC MS-DOS formatted discs

Examples of high density:

  • 1.2MB 5.25" PC MS-DOS formatted discs
  • 1.44MB 3.5" PC MS-DOS formatted discs

The Amstrad's disc controller can only read Double density discs. AMSDOS is limited to it's own disc formats so it can't read PC formatted discs, the filesystems are not compatible. If you want to read PC double density disc formats use DOSCopy on the Amstrad.

3.5" high density Floppy discs have an extra hole. The drive detects the hole and automatically switches to high density recording mode. It is advised that you either cover the holes with some opaque tape, or you use true double density discs.

5.25" high density floppy discs are the same as 5.25" double density discs, e.g. there is no physical difference except for the surface of the disc itself.

The density of the media determines the total capacity of the drive.


This defines the total capacity or capability of the drive. The actual useable amount depends on the filesystem that is written to it.

Amstrad parts numbers

  • 30001 P.C.B. 3" Disc drive
  • 30002 P.C.B. 3" Disc drive
  • Z70312 P.C.B. 3" Disc Drive
  • Z70313 P.C.B. 3" Disc Drive
  • Z70341 P.C.B. 3" Disc Drive
  • Z80264 P.C.B. 3" disc drive

Existing models

Drive Emulators

Usefull Pages

Abbreviations used in French

  • K7 = cassettes/tapes ("Ka Sept")
  • D7 = disquettes/disk ("Dé Sept")