Bit of an update -
I installed a 3.5" floppy as drive A. It's hard to make them fit lol. I had to remove a fair amount of plastic.
I noticed the screw spacing on the side of the CPC is the same as the screw spacing on a 3.5" floppy but the 3.5" sits a little inward of the front of the CPC. It works and I copied the system disks with a floppy in a PC with CPCDiskXP. I couldn't get CPCDiskXP to do *anything* with a USB floppy so I gave up on that.
I have ordered another drive and 50 Disks.
I noticed that the edge connector for the external drive has a couple of +5 Volt pins so I am going to try an external 3.5" disk from the edge connector that uses power from the same connector.
I have been using the composite monochrome output from the video connector with a monitor that has VGA, s-Video and Composite inputs so it can scan down to the low 50Hz PAL frame rate.
I tried connecting the signals from the CPC Video connector to the VGA input by connecting the CPC composite sync to both the vertical and horizontal sync signals going into the monitor. That almost worked but the Hsync was out at the top of the screen as the Vsync was interfering.
I then tried collecting all the signals directly from the gate array and then the image was stable but the active area of the screen started right on the left edge of the screen. It looks like the gate array delays the Hsync signal in some way.
So now I will make a box with a RGBs to colour composite and s-Video converter. I will run the power plug to the box and have a second lead that then conveys power (5 Volts) to the CPC. I will also have a 6 Pin Din lead to connect the box to the CPC. On the output side I will have a composite colour output and an s-Video output for the monitor.
I am going to build the circuit with an AD722 (not AD724) as it has directly coupled inputs. I will be making it the worst possible way to test, ie vero type board in a plastic unshielded box.
I am hoping to get a better picture with the directly coupled inputs but at same time it will be far more sensitive to RF induced into any possible ground loop. The AD722 has both a digital and analog grounds and I haven't yet worked out how would be best to attempt to isolate the two. My concern is that because the circuit in the box shares the same power supply as the CPC then I have to worry about any RF that might be induced into the power cable between the box and CPC, even the earth itself.
I was going to put 100nF caps in the DC input and output of the box and run the digital rail of the AD722 from the 5 Volts. I was then going to connect the Video signal ground to the analog ground of the AD722 and use an inductor to decouple the 5 Volt rail that would otherwise be directly shared with the digital side of the AD722.
Does this sound like it could work or am I lining myself up for failure by sharing the 5 Volts power supply with the CPC and s-Video converter

Any comments
