I have tested a quite interesting breakout board – Serial VGA. It allows to organize multi-windows textual output via RS-232 (TTL) on a VGA monitor.

The maximum window size is 100x50 with 64 colours. It supports up to 9 windows simultaneously. Each window is controlled independently via special escape (^[) sequences.

In general – very useful for small projects on microcontrollers if you don’t bother doing VGA output by yourself (RS-232 output can be implemented even manually if your microcontroller doesn’t support it for some reason). I also tested Serial VGA with Raspberry Pi. The only recommendation is to support the CTS signal line on baud rates faster than 9600. Otherwise the device can loose some characters.

The Serial VGA datasheet.