http://neil.franklin.ch/Projects/SoftVGA/README
author Neil Franklin, last modification 2008.09.21

Introduction to my SOftVGA project

Aim was my desire to experiment with generating an video picture in software
without using an specialised video generator hardware (VLSI or TTLs).

This preferably with an single chip, so use an microcotroller, not an general
microprocessor system.


Making only an B&W picture is too simple and boring.

Making an NTSC or PAL colour picture requires lots of processing power
(basically an 8bit DSP) or using an dedicated analog chip, and so is not so
impressive.

Making an RGB picture for TV is not possible, unless one has an TV with
an full SCART connector with RGB input, which I do not have. S-Video is
still modulated U and V signals.

So I settled for an VGA generator, despite the higher timing requirements
(25.4us vs 40us for the output-useable pixels).


Aim was also for this picture to have an usable text resolution for output
for small computer projects, which requires preferably an 40x25 display, as
32x25 or 32x24 or even worse 32x16 are too little.

This high resolution, and multiple bits per pixel (which precludes using an
shift register) required an AVR microcontroller. With this it turned out to
be just do-able.