need internal information of the old hercules graphics card (hgc)standard

[johannes.black]

I would like to improve the dosbox dos emulator and would like to
implement black/{green,amber} hercules emulation in the program.

Does anybody have good information about the hgc internals?
Additionally I´m interested which colors the hgc green / amber color
represent in todays 24 bit / 32 bit graphic cards (RGB-value)? Also I
´m intersted in the normal afterglow delay in an average hercules
monitor (from green/amber to black). Get the after glow function
exponentially or linear to zero?

Greetings and thanks
jo

 

[Bob Myers]

Additionally I´m interested which colors the hgc green / amber color
represent in todays 24 bit / 32 bit graphic cards (RGB-value)?

RGB values do not, strictly speaking, properly identify a
particular color. You need to know at least the specific
primary colors in question and the "white point" of the
display, and it would be very, very helpful to know the
precise response curve of the display before you could
consider a RGB triple as pointing to one specific color.

However, for what it's worth - the old "amber" phosphor
in the monochrome monitors was almost always the
"P3" type, which may help you find color information re
that particular phosphor. P3 is a medium-persistence
phosphor, and you could probably simulate the "fade"
by dropping the brightness along an exponential curve
such that you got down below 10% of the initial level
in, say, 0.2-0.3 seconds. In contrast, the "green" phosphor
was P31, and had a much shorter persistence.

Bob M.