Schematic: quite easy
VGA mode used: 640x480 @ 31,5kHz/60Hz, (virtual) dot clock 25 MHz, visible information per line: ≈ 80%.
Bitmap size displayed: 128x120x4 (every pixel is a rectangle of 5x4 dot cells), using fixed DOS/Windows/CGA palette.
|Visible picture at different values for RN2 (click radio buttons to switch!)|
The quartz crystal frequency is only 20 MHz (the ATmega88-20 is not overclocked). All components are available at Reichelt. The optimum microcontroller would be ATtiny84-20.
This PCB design (Eagle, SMD) for usual nine-pin SubD adapters uses a plug and a socket, so you have both genders readily available.
Population of this two-sided, 1 mm thick PCB
Freeware, open-source, you can use it for what your want, even commercially. Keep a copyright notice when you use this project with small or no modifications.
Here you see my test bench, and how it works