Amstrad External Disk Drive

Amstrad made two different disk drives for the Amstrad/Schneider CPC range:

• DDI-1: a set consisting of the real DDI-1 (= Disk Drive Interface) and a FD-1 3" disk drive, as well as the CP/M 2.2 license and disk.

This set was for the CPC464 which didn't have a built-in 765 FDC disk controller.

• FD-1: a 3" disk drive as secondary disk drive unit for the CPC664, CPC6128 and CPC464 with DDI-1

There was no official external disk drive for the 6128Plus or even the 464Plus. The difference between a CPC664/CPC6128 and a 6128Plus was simply a changed pin-out which can easily be solved by a new plug on the disk drive's cable.

The 464Plus was harder to equip with a disk drive. Although the pin-out of the expansion port was left unchanged, the DDI-1 cannot be used on the 464Plus without modifications (see Connecting a Disc Interface to CPC464+).

Technical Details

The two disk drives were identical. The only difference was that the DDI-1 shipped with controller, manual and CP/M 2.2 on one disk.

The disk drives were jumpered (more accurately, soldered) to react on both drive select lines, A: and B:.

The cable decided which drive became A: and which one became B: :

• On the CPC664 and CPC6128 computers, DRIVE SELECT 0 was not connected on the external connector, so the drive could only become drive B: on these systems.
• For the DDI-1, DRIVE SELECT 0 was only wired to the outermost connector of the attached cable, while the inner connector was wired to DRIVE SELECT 1 only, thus the drive at the cable's end always became A: while the other one became drive B: accordingly.

Note that the drive also powered the DDI-1 interface when used together with it. Certain pins documented as N/C in the CPC664/CPC6128 manual in fact carry +5V from the drive to the controller. The main reason for this was that you couldn't connect a standard drive with a more common format (5¼" in the beginning, 3½" later and today) and thus cheaper disks as drive A: without modifications, as the DDI-1 wouldn't work without the power fed from the FD-1.

Pictures

• 

  FD-1 (disc drive)

• 

  DDI-1 (disc interface)

• 

  DDI-1 (pcb)

• 

  DDI-1 (schematic)

• 

  DDI-1 (top)

• 

  DDI-1 (bottom)

Covers

• Manuals
• 

  (English) User Manual

• 

  (German) User Manual

• 

  (Spanish) User Manual

• 

  Service Manual

Manuals

• Amstrad DDI-1 (English) Manual
• Amstrad DDI-1 (Spanish) Manual

Service Manual

• Amstrad DDI-1 FD-1 Service Manual

Datasheets

• Media:UPD765 Datasheet OCRed.pdf - uPD765 disc controller
• Media:FDC9229BT Datasheet.pdf - FDC9229BT data separator (that usually assists the uPD765 chip)
• Media:DDI Schematic.png - DDI-1 Schematic (disc interface for CPC464)