IBM 5150

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
Cursor
-
Only
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.
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