Taxan RGB video for Apple II

Taxan RGB Video for 8-bit Apples

Information on the TAXAN Model 410-80 RGB video card and the TAXAN
RGBvision-I for the Apple II. This card doesn't seem to be documented
on the web yet, so here are some things I learned empirically.

Taxan Model 410-80

This is an 80-column RGB video card manufactured by "Video-7" (copyright
1983) that fits into the AUX Connector of an Apple II+ or Apple //e.
Some Taxan video cards include an extra 64KB of RAM, but the model I
have, 410-80, does not.

The card includes a cable with a female 15-pin video connector that
looks compatible with the Apple IIgs video cables, but is
slightly different. First the colors will be completely wrong unless
the green and red pins are swapped.

Secondly, unlike an Apple IIgs RGB port, this is a digital RGB
card. This card appears to use the eight colors of the IBM CGA palette
to approximate the Apple II colors. For word processing, this is fine,
but for games it can make a difference. In particular, the edges of
hi-res graphics sometimes appear grotty. Below is the color mapping,
from the fifteen colors of the low-res Apple II palette.

ACTUAL: DISPLAYED
Black: Black
Magenta: Red
Dark Blue: Blue
Purple: Purple
Dark Green: Green
Grey: Yellow
Medium Blue: Cyan
Light Blue: White
Brown: Black
Orange: Red
Grey: Blue
Pink: Purple
Light Green: Green
Yellow: Yellow
Aquamarine: Cyan
White: White

Pin out

The 15 pin female connector from the Taxan 410-80 card is almost
the same as an Apple IIgs, except that Green and Red are swapped.

Pin 2: Green video
Pin 3: Composite sync
Pin 5: Red video
Pin 9: Blue video
Shell: Ground

Taxan RGB Vision I monitor

Although the color palette is limited when used with the Taxan 410-80,
this is actually an analog RGB monitor. That means you'll get full
color when connected to an analog RGB video source, for example from an
Apple IIgs.

The monitor has three modes, but I only use Mode II:
Mode I: CGA style digital RGBI
Mode II: Apple IIgs style analog RGB
Mode III: Apple III style digital XRGB

Pinout of RGB Vision I monitor

<br />
Taxan female jack (Mode II)<br />
4  3  2  1<br />
8  7  6  5<br />

Pin 1: Unknown, not used with Apple II (?intensity?)
Pin 2: Red
Pin 3: Green
Pin 4: Blue
Pin 5: Ground
Pin 6: Ground
Pin 7: Horizontal/Composite sync
Pin 8: Vertical sync

CGA incompatability

Although my TAXAN RGB Vision I monitor came with a cable that comes from
the Mode II port and ends in a 9-pin male connector that looks
exactly the same as an IBM CGA connector, it does not work as a
CGA monitor. It didn't cause any damage to my monitor, but it didn't
work either.

Likewise, plugging a CGA monitor into the Taxan 410-80 video card didn't
work, but caused no harm.

Here is the pinout of that 9-pin male connector:

1: Ground
2: Ground
3: Red
4: Green
5: Blue
6: Not used with Apple II (intensity?)
7: x - No connection
8: Horizontal / Composite sync
9: Not used with Apple II (V sync)

CGA compatability

I haven't tried yet, but it appears that the Taxan RGBvision I can be
used as a CGA monitor with the proper cable connected and the mode
switch set to Mode I. The Mode I jack on the monitor is an 8-pin DIN
with this pin out:

1: Intensity
2: Red
3: Green
4: Blue
5: Ground
6: Ground
7: Horizontal/Composite sync
8: Vertical sync

Unanswered questions

Is there any way to add 64K of RAM to the 410-80 video card? Probably
not. Many of the chips are socketed, but none are empty and most are
just TTL logic.

Are any games actually unplayable due to the limited palette of the
Taxan 410-80 video card? Unlikely, since most games use the Apple II
high resolution mode which has an even smaller palette.

What is pin 1 on the RGBvision I monitor input jacks? I'm guessing it's
CGA style "intensity".