640x400 black-and-white

A project log for XORYA - extremely low cost game console on PIC32

XORYA game console is just one chip PIC32MX170F256B (32-bit MIPS core, 256K flash, 64K data mem) in DIP28 package and a few other components

shaosSHAOS 12/10/2023 at 05:080 Comments

Xorya is capable of showing 640x400 black-and-white images by constantly switching half-frames 640x200 every frame to make "fake" interlaced video and some NTSC TVs will "stitch" those half-frames to full frame thinking it's truly interlaced video - some examples:

The only problem with fake interlaced screen - sometimes TVs may be confused and switch odd and even lines:

To resolve it just re-connect the cable once or twice and it will stay in sync until reset.

And some TVs will just constantly blink (usually cheap ones).

Source code of the program:

Use GIGA define to show 400-line XBM images ( it's a reference to ZX-Spectrum world where this technique was called "gigascreen" ; )

By default this example shows schematics of color Xorya in 640x200 without GIGA :)