Table of Contents
Advertisement
Preset Row Scan Register Format
Bit
7
6
5
4
3
2
1
0
III
I I I I
I :
Starting Row Scan Count after
a Vertical Retrace
Not Used
This register is used for pel scrolling.
Bit O-Bit 4
Preset Row Scan (Pel Scrolling)-This register
specifies the starting row scan count after a
vertical retrace. The row scan counter
increments each horizontal retrace time until a
maximum row scan occurs. At maximum row
scan compare time the row scan is cleared (not
preset).
Maximum Scan Line Register
This is a write-only register pointed to when the value in the CRT
Controller address register is hex 09. The processor output port
address for this register is hex 3B5 or hex 3D5.
Maxim um Scan Line Register Format
Bit
7
6
5
4
3
2
1
0
I I
I
Bit O-Bit 4
I
I :
Maximum Scan Line
Not Used
Maximum Scan Line-This register specifies the
number of scan lines per character row. The
number to be programmed is the maximum row
scan number minus one.
Cursor Start Register
This is a write-only register pointed to when the value in the CRT
Controller address register is hex OA. The processor output port
32 IBM Enhanced Graphics Adapter
Advertisement
Chapters
Table of Contents
