Scali
Veteran Member
I have two machines which are Plantronics ColorPlus-compatible.
One is the onboard video on my Commodore PC20-III. The other is a Philips P3105 which came with an ATi Small Wonder.
(By the looks of it, the onboard video of the PC20-III is just an ATi Small Wonder copy-pasted onto the mainboard... but Commodore does not mention ATi anywhere).
Anyway, there is not a lot of information on programming the extra modes.
I have found this manual for the PC20-III: http://dostalgie.de/downloads/pc10III-20III/PC10III_OM_COMMODORE_EN_DE.pdf
It contains a dump of the CRTC registers, and info on how the pixels are made up.
This sounds to me like the 16-colour mode is technically always on (it does not seem to mention any extra control register to enable/disable it... I will have to take a closer look at the CRTC register dump, but it says it's the same as CGA, which it probably is). So just writing pixel data to the second plane should 'blend' with the regular CGA plane to enable extra colours.
I will have to experiment with that.
The only other information I have been able to find so far is this: http://www.seasip.info/VintagePC/cga.html
It mentions an extra control register at 03DDh, which apparently controls how the two planes work together.
The same register is also described here: http://www.seasip.info/AmstradXT/1640tech/section1.html#1.11.3.3
Aside from that, I have found some programming example on the ATi Small Wonder disk, which I have yet to study closer, but that may be specific to the ATi card, rather than generic Plantronics-code.
So, does anyone have any experience programming Plantronics ColorPlus and/or has some extra documentation on it?
One is the onboard video on my Commodore PC20-III. The other is a Philips P3105 which came with an ATi Small Wonder.
(By the looks of it, the onboard video of the PC20-III is just an ATi Small Wonder copy-pasted onto the mainboard... but Commodore does not mention ATi anywhere).
Anyway, there is not a lot of information on programming the extra modes.
I have found this manual for the PC20-III: http://dostalgie.de/downloads/pc10III-20III/PC10III_OM_COMMODORE_EN_DE.pdf
It contains a dump of the CRTC registers, and info on how the pixels are made up.
This sounds to me like the 16-colour mode is technically always on (it does not seem to mention any extra control register to enable/disable it... I will have to take a closer look at the CRTC register dump, but it says it's the same as CGA, which it probably is). So just writing pixel data to the second plane should 'blend' with the regular CGA plane to enable extra colours.
I will have to experiment with that.
The only other information I have been able to find so far is this: http://www.seasip.info/VintagePC/cga.html
It mentions an extra control register at 03DDh, which apparently controls how the two planes work together.
The same register is also described here: http://www.seasip.info/AmstradXT/1640tech/section1.html#1.11.3.3
Aside from that, I have found some programming example on the ATi Small Wonder disk, which I have yet to study closer, but that may be specific to the ATi card, rather than generic Plantronics-code.
So, does anyone have any experience programming Plantronics ColorPlus and/or has some extra documentation on it?