Hi Bryce,
I have installed a floppy into the CPC case to work as drive A.
I followed a picture you have here -
Adaptor Cable for Internal HxCand it didn't work.
The three signals that seem to be transposed in the picture are ...
Main Board - Floppy Drive
NC -> /DriveB
Drive0 -> MotorA
/Index -> /Index
NOT transposed is -
/MotorOn -> /MotorB
I looked up how a 'standard' 3.5" floppy works and found that by default they are hard wired as DriveB
So I just transposed the last two wires - /Index to give -
/MotorOn -> /MotorB
NC -> /DriveA
/Drive0 -> /DriveB
empty -> gap
/Index -> /Index
Now it seems to work .. it lights when I type |A the motor runs and I can hear it seeking. I don't yet have a formatted disk so I get an error.
I also saw this picture on another page but I can't find it now.
I also bridged the /RDY signal to ground on the Main board connector as new 3.5" use this signal for DiskChange instead.
I wanted to do it this way because when I need to replace the drive I can get *any* standard PC 3.5" and just plug it in without needing to worry about jumpers.
I don't have an Amstrad monitor so I am just using a 5 Volt 3 Amp 'Wall Wart' and NO 12 Volt supply. Newer 3.5" floppy drives don't use 12 Volts anyway.
The CPC6128 is 1.7 Amp and the Floppy Drive is 0.96 Amp so the 3 amp supply is fine.
One other thing that I might mention is that the CPC6128 Floppy Power connector uses RED for 12 Volts and Orange for 5 Volts. On my CPC they had the same colours / positions on the connector as a ATX supply meaning they were transposed when compared to a normal 3.5" floppy. I just swapped the pins in the connector at the end of the floppy power lead. Oops - except that orange is yellow (Sorry I am colour blind).
This would be an issue for people using an amstrad monitor and have 12 Volts connected to the CPC as the 12 Volts would be going into the floppies 5 Volt pin. I am hoping that this info might be helpful for someone.
The confusions started for me when I read HXC / Internal adaptor. I read this to mean HXC and Internal Floppy Drive adaptor cable. It now looks to mean HXC running on internal floppy connector adaptor cable. Or something like that.
Now I will put a PC together with a 3.5" floppy and XP and do some formatting / disk dumps.