Note:  To access these display modes, you would do the normal GRAPHICS call, followed by a
POKE to the GTPRIOR register (623) with one of these values:

64-127:  Mode 9 (monochrome shades)
128-191:  Mode 10 (programmable registers)
192-255:  Mode 11 (various hues, all one luminance)

So for example, to call GRAPHICS 0/9, you do GRAPHICS 0, then POKE 623 with a value between 64-127.

On all mode 9 displays, the background color only is controlled from POKE 712,hue*16 or SETCOLOR 4,hue,0

On all mode 11 displays, the luminance is also controlled from POKE 712,0-14 or SETCOLOR 4,0,luminance

On mode 10 displays, the background color is controlled through PCOLR0 (704) which is the same register
used for Player 0.  This means that Player 0 will not display in these modes unless on top of a different color.  I have noticed that other players and missiles have trouble displaying on this background as well.  A possible remedy for this is by redefining the bit patterns on CHR$(32) (space) to be one of the other programmable colours, which are controlled from various player and playfield registers, some of which may not be accessible in some display modes.

All of these modes have been documented on a real Atari except for modes 12 and 13, which I did on AtariWin800,
so the actual results may be different.  You may want to test this on a real Atari.

Another caveat:  There is a known issue with Atari800Win Plus 4.1 regarding Graphics 12 and 13 with the GTIA mode set.  The emulator will not display control characters or lowercase (ATASCII 0-31 and ATASCII 96-127) in these modes, instead substituting ATASCII characters 32-97.  This causes the graphics modes not to display properly in the emulator.  These modes will, however, display properly with other emulators such as Atari800 and Atari++. 


Documentation of GTIA text modes

Graphics 0/9, 0/10, 0/11
========================
These modes use a 2x8 display grid.  Each pixel is controlled by 4 bits which determine one of 16 colours.
When the character is inversed (ATASCII 128-255) the 1 and 0 bits in the pixel are reversed.  


Graphics 0/9
------------
16 monochrome shades displayable.

ATASCII:  0000  0001  0010  0011  0100  0101  0110  0111  1000  1001  1010  1011  1100  1101  1110  1111
-------   ----  ----  ----  ----  ----  ----  ----  ----  ----  ----  ----  ----  ----  ----  ----  ----
0-127        0     1     2     3     4     5     6     7     8     9    10    11    12    13    14    15 (GRAPHICS 9
128-255     15    14    13    12    11    10     9     8     7     6     5     4     3     2     1     0   colours)


Graphics 0/10
-------------
9 programmable colours (all four player registers and all five playfield registers)
In this mode, the bit combinations correlate to Graphics 10 colours.  As in Graphics 10, colors 8-11 correlate to register 712 (SETCOLOR 4) while colors 12-15 are identical to colors 4-7 (708-711 or SETCOLOR registers 1-3)

ATASCII:  0000  0001  0010  0011  0100  0101  0110  0111  1000  1001  1010  1011  1100  1101  1110  1111
-------   ----  ----  ----  ----  ----  ----  ----  ----  ----  ----  ----  ----  ----  ----  ----  ----
0-127      704   705   706   707   708   709   710   711   712   712   712   712   708   709   710   711 (colour
128-255    711   710   709   708   712   712   712   712   711   710   709   708   707   706   705   704   registers)


Graphics 0/11
-------------
16 hues displayable, hues 1-15 are one luminance while bit pattern 0000 correlates to the background.

ATASCII:  0000  0001  0010  0011  0100  0101  0110  0111  1000  1001  1010  1011  1100  1101  1110  1111
-------   ----  ----  ----  ----  ----  ----  ----  ----  ----  ----  ----  ----  ----  ----  ----  ----
0-127        0     1     2     3     4     5     6     7     8     9    10    11    12    13    14    15 (GRAPHICS 11
128-255     15    14    13    12    11    10     9     8     7     6     5     4     3     2     1     0   colours)



GRAPHICS 1/9, 1/10, 1/11, 2/9, 2/10, 2/11
=========================================
These character modes use a 4x8 grid, similar to ANTIC 4/5 (GRAPHICS 12/13).  As in regular Graphics 1 or 2, only 64
characters at a time can be displayed.  To display the other 64 characters requires a POKE to register 756.

Additionally, ATASCII 0-63 is undisplayable in these modes (all bit pairs
correspond to the background colour), while the other three ranges (64-127, 128-191, 192-255) correspond to three
palettes, containing between 2 and 3 colours each plus the background colour, all programmable through bit-pairs as 
in the ANTIC 4/5 modes.

GRAPHICS 1/9,2/9
----------------
10 monochrome shades, arranged across three pallettes.  Bit 00 corresponds to the background colour on all pallettes.
Each pallette has three unique colours plus the background colour.  GRAPHICS 9 colours 6, 7, 8, 11, 12, and 13 are unavailable in these modes.
 
              BIT PAIRS
         ------------------
ATASCII: 00    01   10   11   

64-127:   0     1    4    5   (GRAPHICS 9 COLORS)  
128-191:  0     2    9   10
192-255:  0     3    14  15


GRAPHICS 1/10,2/10
------------------
8 programmable colours, arranged across three pallettes.  Bit 00 again corresponds to the background colour, in this
case PCOLR0 (704).  Register 710 (Setcolor 2) is unavailable in this mode.  In addition, register 708 is shared between two pallettes (64-127 and 192-255) while on the second pallette (128-191) register 712 (SETCOLOR 4) corresponds to bit pairs 10 and 11.
  
              BIT PAIRS
         ------------------
ATASCII: 00    01   10   11   

64-127:  704, 705, 708, 709 
128-191: 704, 706, 712, 712 
192-255: 704, 707, 708, 711 



GRAPHICS 1/11,2/11
------------------
10 hues of one luminance, arranged across three pallettes, in the same manner as 1/9 and 2/9.  GRAPHICS 11 colours 6, 7, 8, 11, 12, and 13 are unavailable in these modes.

              BIT PAIRS
         ------------------
ATASCII: 00    01   10   11     Graphics 11 colors

64-127:   0     1    4    5     (black, yellow, purple, indigo)
128-191:  0     2    9   10     (black, orange, blue, teal)
192-255:  0     3    14  15     (black, red, olive, gold)



GRAPHICS 12/9, 13/9, 12/10, 13/10, 12/11, 13/11
===============================================
These displays use a 2x8 design grid, as in the 0/9-0/11 modes, however the available colours are arranged across
two pallettes, with the second pallette accessible through ATASCII 128-255 (inverse).  With the exception of modes 12/10 and 13/10 (which have all 9 mode 10 colours available), there are two fewer colours available in these modes than in 0/9 and 0/11.

The rules for displaying colors work like this:  Each 4 bit combination is split into two bit pairs which are interpreted by the GTIA chip.  There are basically four rules in play here:

1.  Any 4 bit combination which contains at least one high bit pair combination (11) will enable alternate palleting for that bit combination in inverse.  This means that the color associated with this 4-bit combination will change if the character is inversed.  This covers the combinations 0011, 0111, 1011, 1100, 1101, 1110, and 1111

2.  The bit pair combinations 00 and 01 are treated exactly the same when processed by the GTIA chip.  When any combination of 00 and 01 are in the same 4-bit combination, the resulting color is the background color.  In combinations where colors are displayable but one of the bit pairs are 00 or 01, changing the pairing of the lower two bit combinations will not change the color.  This leads to a lot of color redundancy in the 4-bit combinations.  In fact, the second four 4-bit combinations (0100, 0101, 0011, 0101) give the exact same colors as the first four (0000, 0001, 0010, and 0011).

3.  The bit pair combination 10, when paired either with itself, or the lower bit pairs (00 and 01) enable a color which is unchanged between the normal and inverse pallettes.  

4.  The number of redundant combinations is increased in modes 12/10 and 13/10 because of the fact that Graphics 10 colors 8-11 are all mapped to register 712, while colors 12-15 are all duplicates of 4-7, being mapped to 708-711 respectively.


Despite the fewer bit combinations available, these modes are not entirely useless.  They can be used in character-flip software display modes, one example being a mode I have named CIN 12, which flips every VBI between a normal ANTIC 4 (Graphics 12) character set, and a character set under Graphics 12/11, enabling a display pallette of 36 colors per character grid, and 60 colors total displayable onscreen at once, at ANTIC 4 pixel resolution.

A warning:  These modes will not display properly on AtariWin800 Plus 4.1 because of a bug in the emulator which substitues the Upper Case characters and punctuation (ATASCII 32-95) on top of the lowercase and control characters, thereby preventing the latter from being displayed.  This bug is not present in other emulators such as Atari800 and Atari++.

GRAPHICS 12/9, 13/9
-------------------
14 monochrome shades.  Colours 0, 1, 4, and 5 are shared between both pallettes.  9 unique colours can be displayed
within each pallette.  GRAPHICS 9 colours 11 and 14 are unavailable in this display mode.

ATASCII:  0000  0001  0010  0011  0100  0101  0110  0111  1000  1001  1010  1011  1100  1101  1110  1111
0-127        0     0     1     2     0     0     1     2     4     4     5     6     8     8     9    10  
128-255      0     0     1     3     0     0     1     3     4     4     5     7    12    12    13    15


GRAPHICS 12/10, 13/10
---------------------
9 programmable colours.  The entire range of GRAPHICS 10 colours are available here.  Color registers
704, 705, 708, and 709 are shared between both pallettes.  Due to a quirk in the Atari color register layout
in GRAPHICS 10, there is one fewer colour available in the second pallette than in the first.  Pallette 1 can display 7 unique colours, while pallette 2 displays 6 unique colours. 

ATASCII:  0000  0001  0010  0011  0100  0101  0110  0111  1000  1001  1010  1011  1100  1101  1110  1111
0-127      704   704   705   706   704   704   705   706   708   708   709   710   712   712   712   712   
128-255    704   704   705   707   704   704   705   707   708   708   709   711   708   708   709   711


GRAPHICS 12/11, 13/11
---------------------
14 hues of one luminance, arranged in the same manner as GRAPHICS 12/9 and 13/9.  Colours 0, 1, 4, and 5 are shared, with 9 unique colours in each pallette.  Again, GRAPHICS colours 11 and 14 are unavailable.

ATASCII:  0000  0001  0010  0011  0100  0101  0110  0111  1000  1001  1010  1011  1100  1101  1110  1111
0-127        0     0     1     2     0     0     1     2     4     4     5     6     8     8     9    10  
128-255      0     0     1     3     0     0     1     3     4     4     5     7    12    12    13    15







