Version 5 Breadboard VGA video CRTC & Video DAC

A project log for Nanocomp 6809 8 Bit Retro Computer on Breadboards

Wireless World Magazine in January and June 1981 published this design. Reproduced on solderless breadboards using the original Monitor ROM

dave-henryDave Henry 11/23/2022 at 21:520 Comments

The next stage of the Nanocomp project. In Version 5  we are starting to add a VGA compatible video controller on breadboards to the project. The introduction video V01  explains the steps which will build the controller in stages. Some screenshots of an earlier version of the project included below too.

The second video starts to build out the video controller with the Motorola 6845 compatible CRTC to generate the Vertical and Horizontal Sync outputs and a simple resistor video Digital Analogue Converter (DAC) to generate VGA compatible Red Green Blue signals.

The image below shows the RGB inputs connected to the CRTC Memory Address lines to generate a test pattern showing the 16 colours generated by the simple resistor DAC.

V5 Schematic Diagram updated with initial video card details in Nanocomp6809V5.pdf in files section. KiCad files uploaded in GitHub