RGBTOHDMI

The RGBtoHDMI interface converts the "digital" RGB video signal from vintage computers like the BBC Micro or PC MDA/CGA/EGA to HDMI or DVI compatible with most modern TVs/Monitors. The interface comprises a Raspberry Pi Zero and a specially designed Hat containing a small CPLD. Custom firmware on the Raspberry Pi, in conjunction with the CPLD, is able to correctly sample each of the supported video modes to give a pixel-perfect rendition. The HDMI output is locked to the input so there are no frame drops, repeats or tears and it also has low lag of around 4 milliseconds (less than a quarter of a frame )

An addon analog interface is available for the 6-12 bit versions of the converter to support a limited number of computers with a few levels of analog RGB / YUV output such as Amstrad CPC, Spectrum, Atom, Dragon or Tandy Color Computer, or monochrome composite output such as Apple II /IIe/IIc, UK101, Superboard II, ZX80 and ZX81. Note this interface can only distinguish a few analog levels and is not suitable for systems with many levels of RGB or YUV.

One unusual feature of the converter is optional integer scaling where one original pixel on the computer is scaled to an exact number of lcd pixels without using any interpolation filtering. This results in the low resolution output from real hardware looking as clean and sharp as sources output at the native resolution of the lcd (see the Gallery of Screencaps for examples) although you can use filtering if you prefer.

Due to the way the video is sampled and re-quantised, when everything is setup correctly the output is totally noise free even when passing through an analog stage and it effectively makes the output of real hardware look like it is coming from an emulator.

We are currently selling the following versions -

1) Fully Populated Board - Just plug into a Raspberry Pi 2 WH, load the image, attach cables and start running!

2) Full Board + Raspberry Pi Zero 2WH - All you need to do is attach all cables and start running!

3) Board + Pi + Case - Same as #2 but includes white resin printed case.

(PCB and 3D parts made and PCB populated in 3rd party 3D+PCBA facility overseas,  Raspberry Pi sourced nationally. This is a hoglet67 from Github project, our use is from their GNU General Public License v3.0 available online.