The Plantronics Colorplus is a graphics card for IBM PC computers, first sold in 1982. It implements a superset of the then-current CGA standard, using the same monitor standard (4-bit digital TTLRGBI monitor) and providing the same pixel resolutions.[1] It was produced by Frederick Electronics (of Frederick, Maryland), a subsidiary of Plantronics since 1968, and sold by Plantronics' Enhanced Graphics Products division.[2][3]
The Colorplus has twice the memory of a standard CGA board (32k, compared to 16k). The additional memory can be used in graphics modes to double the color depth, giving two additional graphics modes—16 colors at 320 × 200 resolution, or 4 colors at 640 × 200 resolution.[4]
Plantronics 320 × 200 with 16 colors graphics resolution, corrected for aspect ratioPlantronics 640 × 200 with 4 colors graphics resolution, corrected for aspect ratio
CGA compatible modes:
160 × 100 16 color mode (actual a text mode using , ▌, ▐ and █)
320 × 200 in 4 colors from a 16 color hardware palette. Pixel aspect ratio of 1:1.2.
640 × 200 in 2 colors. Pixel aspect ratio of 1:2.4
40 × 25 with 8 × 8 pixel font text mode (effective resolution of 320 × 200)
80 × 25 with 8 × 8 pixel font text mode (effective resolution of 640 × 200)
"New high-resolution" text font, selectable by hardware jumper
The "new" font was actually the unused "thin" font already present in the IBM CGA ROMs, with 1-pixel wide vertical strokes. This offered greater clarity on RGB monitors, versus the default "thick" / 2-pixel font more suitable for output to composite monitors and over RF to televisions but, contrary to Plantronics' advertising claims, was drawn at the same 8 × 8 pixel resolution.
Software support
Few software made use of the enhanced Plantronics modes, for which there was no BIOS support.
A 1984 advertisement[2] listed the following software as compatible:
Some contemporary software has added support for Plantronics modes:
Planet X3, released by American YouTuber David "The 8-Bit Guy" Murray in 2019, was the first video game known to have Colorplus support (320 × 200 with 16 colors). This support was added by Planet X3 enthusiast Benedikt Freisen.[7]
Attack of the Petscii Robots by American YouTuber David "The 8-Bit Guy" in 2020, ported to MS-DOS computers with a graphics mode providing support for Plantronics Plus.
FastDoom, a port of Doom (1993 video game) developed by Victor Nieto, added support for ColorPlus 320 × 200 with 16 colors mode in 2021.[9]
Hardware clones
Some third-party CGA and EGA clones, such as the ATIGraphics Solution and the ParadiseAutoSwitch EGA 480,[10] could emulate the extra modes (usually describing them simply as 'Plantronics mode').
