IBM 5150 PC Technical Reference (6025005, August, 1981) (PDF)

Table 6. 6845 Register Description
ADDR REG. REGISTER 40x25 80x25 GRAPHIC
REG. # TYPE UNITS I/O ALPHA ALPHA MODES
0 RO Horizontal Char. Write 38 71 38
Total
Only
1 R1 Horizontal Char. Write 28 50 28
Displayed
Only
2 R2 Horiz. Sync Char. Write 20 5A 20
Position
Only
3 R3 Horiz. Sync Char. Write OA OA OA
Width
Only
4 R4 Vertical Total Char. Write 1F 1F 7F
Row Only
5 R5 Vertical Total Scan Write 06 06 06
Adjust Line Only
6 R6 Vertical Char. Write 19 19 64
Displayed Row Only
7 R7 Vert. Sync Char. Write 1C 1C 70
Position Row Only
8 R8 I nterlace Mode - Write 02 02 02
Only
9 R9 Max Scan Scan Write 07 07 01
Line Addr. Line Only
A R10 Cursor Start Scan Write 06 06 06
Line Only
B R11 Cursor End Scan Write 07 07 07
Line Only
C R12 Start Addr. (HI - Write 00 00 00
Only
0 R13 Start Addr. (Ll - Write 00 00 00
E R14
Only
Cursor - Read/ XX XX XX
Addr. (HI
Write
F R15 Cursor - Read/ XX XX XX
Addr. (Ll
Write
10 R16 Light Pen (HI - Read XX XX XX
Only
11 R17 Light Pen (Ll - Read XX XX XX
Only
Note: All register values are given in hexadecimal.
2-56