Deluxe Monochrome Text Adapter  (250-3046C) Programming Faxback Doc. # 2151

The following information is used to set the MODE Registers:

DTDA REGISTER VALUES

   ┌───────────────────┬─────────────────┬─────────────┐
   │ Resolution:       │     80 x 25     │     80 x 25 │
   │ Adapter Mode:     │ Monochrome Text │ Color Text  │
   ├───────────────────┼─────────────────┼─────────────┤
   │ R0--HOR TOTAL     │     61          │     61      │
   │ R1--HOR DISP      │     50          │     50      │
   │ R2--HYSNC POSN    │     52          │     52      │
   │ R3--HS WIDTH      │     0F          │     0F      │
   │ R4--VERT TOTAL    │     19          │     19      │
   │ R5--VERT ADJ      │     06          │     06      │
   │ R6--VERT DISP     │     19          │     19      │
   │ R7--VSYNC POSN    │     19          │     19      │
   │ R8--INTERLACE     │     02          │     02      │
   │ R9--MAX SCAN      │     0D          │     0D      │
   │ R10--CUR START    │     0B          │     0B      │
   │ R11--CURSOR END   │     0C          │     0C      │
   │ R12--START (H)    │     00          │     00      │
   │ R13--START (L)    │     00          │     00      │
   │ R14--CURSOR (H)   │     00          │     00      │
   │ R15--CURSOR (L)   │     00          │     00      │
   │ MODE REG          │     29          │     2D      │
   └───────────────────┴─────────────────┴─────────────┘

Notes: 

* All values given are in HEX.
* Use CRTC I/O addresses 3B4 (register number) and 3B5 (register value)

MODE register I/O address of 3B8

Blinking Text:

The background intensity bit (80 of ODD bytes) in the video display word is 
shared with the character BLINK logic. If bit 20 of the MODE register is a 0, 
then all 16 colors are available for character backgrounds. If the bit is set 
to a 1, the background intensity bit (80) is changed to be a BLINK CHARACTER 
bit.

Mode Control Register:

Bit  Function

08   VIDEO ENABLE--When set to a "0" the video displays are turned off. The 
     monochrome display SYNC signals are set to the OFF state and all video 
     outputs are turned off.

20   BLINK ENABLE--When set to "0" text characters can not blink. When set to 
     a "1" the BACKGROUND INTENSITY bit (80) of the display RAM character 
     attribute byte will control the blinking of the character (if set, the 
     character will blink).

Text Mode:

The even byte of each word contains the number of the character to display. 
The IBM standard character set contains 256 unique characters numbered from 
0-255.

The odd byte (attribute byte) determines the shade of the character dots and 
their surrounding background. The lower four bits contain the shade code of 
the character's dots. If bit 0 (B) is set to a 1, then underline is enabled. 
The upper four bits determine the shade of the dots in the character matrix 
that that surround the character outline.

Even Byte Character Code:

Bits:  7   6   5   4   3   2   1   0
       character code 00-FF

Bits:  7   6   5   4   3   2   1   0
       I   R   G   B   I   R   G   B

       BACKGROUND        FOREGROUND