A Universal Floppy Disk Drive Adapter for the Amstrad / Schneider CPC 464
A versatile floppy disk drive adapter board for the Amstrad / Schneider CPC. This printed circuit board (PCB) is primarily intended for the CPC 464.
The Gerbers are here.
Connecting disk drives other than the standard Amstrad DD1 / FD1 drives to the CPC via the DDI-1 disk controller usually requires some floppy cable mods. Moreover, these mods usually fix the drive to either being CPC A or B drive.
With this adapter board, one can flexibly use the DIP switches to select 2 out of 3 possible disk drives, and flexibly determine which one is A or B. Moreover, no more (destructive) cable mods are required with this board.
The following drives can be used:
- the standard Amstrad DD1 / FD1 3" floppy
- standard PC 3.5" floppy (with READY signal if possible)
- 5.25" floppy (with READY signal if possible)
- Gotek floppy drive
If the drive does no emit the READY signal, then it can be "faked" by grounding the READY line with the corresponding READY DIP switch (this is a standard CPC floppy cable hack).
The pictures show an application example - I am using the Amstrad DDI-1 disk controller and an old 2bay SCSI enclosure.
Notice that the sockets labeled I1 and I2 are the input sockets for the Amstrad DDI-1 connectors - in case of the DDI-1 controller, both of these need to be used, in order to recover the A (DS0) and B (DS1) drive selection lines. With a different controller it may be sufficient to only use one of these sockets. Also, O1, O2, and O3 are output sockets and are used for connecting the drives. Moreover, 5V is not supplied over the adapter.
Please note that by default / factory setting, the DDI-1 is powered by the DD1 / FD1 3" disk drive. However, this adapter DOES NOT connect the 5V power lines in order to protect other drives - powering drives over the ribbon cable was a proprietary Amstrad invention, and can destroy drives such as the Gotek. Hence, in order to be able to use the DDI-1 with this adapter board, a DDI-1 modification has to be applied: the DDI-1 has to be powered over the CPC expansion bus. This modification is described here..
I recommend putting a switch in the DDI-1 such that the mod can be turn on and off as needed.
Simple. Each drive has a Drive Select 0 (DS0) and Drive Select 1 (DS1) input. By default, DS0 is used for the A connector of the DDI-1, and DS1 for its B connector. Moreover, DS1 is not connected for A, and DS0 is not connected for B in the DDI-1 floppy cable. The purpose of the two I1, I2 sockets is to recover both DS0, DS1 signals. In addition, each individual disk drive is also jumpered (or configured) to either respond to DS0 or DS1; sometimes, it response to both, like the Amstrad DD1 / FD1 drives.
Hence, for each of the three connected drives, the DIP switch allows to select the following signal routes: A -> DS0, B -> DS0, A -> DS1, and B -> DS1. A drive which is jumpered to respond to DS1 can be made to act as an A drive via A -> DS1; vice versa, a drive that is configured for DS0 can be made to react to B: B -> DS0. The routing can be determined for 2 of the 3 connected drives individually. To disable a drive, make sure all DIP switches for the correpsonding drive are in OFF position (it will then neither respond to A nor B).
The PCBs can be ordered from OshPark.