mamedev
Incorrect video attribute styling in DEC VT102 and VT240
The video attribute styling of vt102 and vt240 are not quite correct, DEC had thorough QA procedures ensuring that products were made to conform to, reading documents is difficult and leaves some bits to interpretation. Here is a video of the terminal test-suite vttest - which is often used when developing terminals, running on VT220 and VT320 hardware showing consistent attribute rendering between products. https://www.youtube.com/watch?v=03Pz5AmxbE4
The vt102 machine in mame has one attribute wrong in normal video mode: reverse video + blinking. vtvideo alternates between regular state and inverted state, while actual hardware alternates the background between dim and regular intensity. This also affects the blinking of non-inverse attributes when using dark on light mode.
The vt240 machine is another DEC terminal in mame that overall works well, its interpretation of video attributes is further from matching real hardware.
The attributes in the v240 aren't hard coded in any way, it's all done by the upd7220 and the discrete hardware attached to it. The main problem is the logic unit (http://bitsavers.org/pdf/dec/terminal/vt240/EK-VT240-TM-001_VT240_Technical_Manual_Aug84.pdf#page=162) which is a black box and I think it's mostly right but there are clearly some remaining problems (https://mametesters.org/view.php?id=7156, https://forums.bannister.org/ubbthreads.php?ubb=showflat&Number=114082#Post114082).
