Specifications

Appendix A: Chipset and I/O map
71
x3C4 R/W Sequencer index
x3C5 R/W Sequencer data
x3C6 R/W
R/W
Video DAC pixel mask
Hidden DAC register
x3C7 R
W
DAC state
Pixel address read mode
x3C8 R/W Pixel mask write mode
x3C9 R/W Pixel data
x3CA R Feature control readback
x3CC R Miscellaneous output readback
x3CE R/W Graphics controller index
x3CF R/W Graphics controller data
Table A-27. EGA controller
I/O Addr Functional group R/W Usage
Table A-28. CGA controller
I/O Addr Functional group R/W Usage
x3D4 CGA controller R/W CRT controller index (color)
x3D5 R/W CRT controller data (color)
x3DA R
W
Input status register 1 (color
Feature control (color)
Table A-29. COM 3 serial poert
I/O Addr Functional group R/W Usage
x3E8-
x3EF
COM 3 serial port R/W COM 1 moved to COM 3 (see
register description in Ta b l e A - 3 2 ,
Serial I/O (COM 1) port on page 72
Table A-30. Floppy disk controller
I/O Addr Functional group R/W Usage
x3F0 Floppy disk controller R Status register A
x3F1 R Status register B
x3F2 R/W Digital output register
x3F3 R/W Tape driver register
x3F4 R
W
Main status register
Data rate select register
x3F5 R/W Data register
Ta b l e A - 3 1 . P r i m a r y I D E
I/O Addr Functional group R/W Usage
x3F6 Primary IDE R/W Alternate status/device control
x3F7 R
W
Digital input register
Configuration control register