September 12, 2025
VGA output for the CPC 6128
I got this Amstrad CPC 6128 with a bulky CRT monitor. I’m pretty sure ‘true’ retrocomputing fans would enjoy the ‘genuine’ experience it provides, but I don’t.
The monitor also contains the power supply for the CPC. Both the CRT itself and this PSU are the kind of electronic that don’t deal well with time. I don’t trust them.
Thus, to gain space, confidence and display comfort, I’ve decided to get a VGA adapter.
This is not as simple as it seems. You can more or less twiddle with passive adapters for either VGA or TV (using SCART or composite cables), but it highly depends on the receiver and luck. I’m not a lucky guy.
There are relatively expensive “general purpose” adapters from “retro computers” to DVI and/or HDMI, usually FPGA-based, but lot of software on the Amstrad CPC use some video “tricks” that don’t behave well with those.
Fortunately, there’s a great project, recent (2024), and specifically made and tested for the Amstrad CPC. The developer explicitely tested all those corner cases and fixed his adapter accordingly. To my knowledge, that’s the only adapater reaching this level of compatibility.
It’s called VGA4CPC. It’s based on a Raspberry Pi Pico and requires only a handfull of other components. It’s all open source. I mean “really open source”, as you get not only the source code for the software, but also the KiCad schematics. And not only a blurry PDF of the schematic, or even a photo, as lot of “open source” hardware projects do.
Once found the perfect (for me at least) solution, everything went smooth. I ordered PCB and components (even made a group purchase for this: English, French), soldered it, programmed the Pi Pico (dang, it’s really just a drag&drop), and voilà, it just works.
The Amstrad video signal is 50Hz. The adapter can output a VGA 50Hz signal, which is ideal as it’s synced with the input, but you need a VGA display that accepts that. I don’t have one, so I use the 60Hz output, which will probably give some glitches with demanding games/demos.
Anyone knows of where there would be someone who would sell this as a plug’n play device already soldered and programmed ?
It’s absolutely the solution I’m looking for being through many other different solutions with more or less success but never near perfect.
Feel free to reach out on therealholger@gmail.com
Thanks
We did group purchases for kits (see links in the article), but nobody is proposing a final-and-tested product..
Holger, there is a community project on PCBWay which is most of the way there. You’d still need to connect to 9 pin DIN and flash the device once. Unfortunately, I am waiting for the author to respond to PCBWay about their assembly queries. Will post link separately in case links are flagged as SPAM.
The PCBWay SMT version as a community project ready for assembly: https://www.pcbway.com/project/shareproject/Amstrad_Schneider_CPC464_664_6128_VGA_Output_952d1484.html
I know this VGA monitor. It is 16:10 aspect ratio rather than the more common 4:3 or 16:9. If you think about it, if the Amstrad CPC had square pixels, mode 1 would be a 16:10 mode (320 x 200, / 2 = 160 x 100, / 10 = 16 x 10 ). Did you manage to fill the screen in mode 1 using this adaptor board?
No more than what is seen on my photo upthere.
Anyway, you dont want the 320×200 to fill the screen, there’s the BORDER.
And one great feature of this adapter is that it also works with all the “tricks” to use this border real-estate, as used by games & demos alike.