A veri nice escursion on the ZX80 and ZX81 video generation

[marste]

A bit longish but very nicely done.
This series of videos take you step by step to the final design:
1. https://www.youtube.com/watch?v=pVQJxV9JCSE - ZX80/81 Video circuit generated from scratch
2. https://www.youtube.com/watch?v=T5yu_0K32s8 - Video circuit revealed, hi-res display of 256 x 192 pixels
3. https://www.youtube.com/watch?v=Y1mMUuR7wLs - Text
4. https://www.youtube.com/watch?v=Lr5wi_q69Pw - Display File
5. https://www.youtube.com/watch?v=JHETqNwk7gs - How interrupt is generated for HSYNC
6. https://www.youtube.com/watch?v=QPGE8JjC700 - ZX80 fully explained
7. https://www.youtube.com/watch?v=xIfiWr-CRmk - ZX81 Video Circuit "grand finale" with all the explanations of the ZX81 video circuit