RGBTOHDMI Base

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 )

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.

(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.