6.1.4ICH Fixed I/O Registers
Port | Register Name |
00h, 02h, 04h, 06h | Channel 0, 1, 2, 3 DMA Base & Current Address Regsiter |
C0h, C4h, C8h, CCh | Channel 4, 5, 6, 7 DMA Base & Current Address Register |
01h, 03h, 05h, 07h | Channel 0, 1, 2, 3 DMA Base & Current Count Register |
C2h, C6h, Cah, CEh | Channel 4, 5, 6, 7 DMA Base & Current Count Register |
Aliased at | |
20h | Master PIC ICW1 Init. Cmd Word 1 Register |
| Master PIC OCW2 Op Ctrl Word 2 Register |
| Master PIC OCW3 Op Ctrl Word 3 Register |
21h | Master PIC ICW2 Init. Cmd Word 1 Register |
| Master PIC ICW3 Init. Cmd Word 1 Register |
| Master PIC ICW4 Init. Cmd Word 1 Register |
| Master PIC OCW1 Op Ctrl Word 3 Register |
Aliased at | |
| |
| |
| |
40h | Counter 0 Interval Time Status Byte Format |
| Counter 0 Counter Access Port Register |
41h | Counter 1 Interval Time Status Byte Format |
| Counter 1 Counter Access Port Register |
42h | Counter 2 Interval Time Status Byte Format |
| Counter 2 Counter Access Port Register |
43h | Timer Control Word Register |
| Timer Control Word Register Read Back |
| Counter Latch Command |
Aliased at | |
61h | NMI Status and Control Register |
70h | NMI Enable Register |
| |
71h | |
72h | Extended RAM Index Register |
73h | Extended RAM Target Register |
Aliased at | |
Aliased at | |
81h, 82h, 83h | Channel 2, 3, 1 DMA Memory Low Page Register |
Reserved Page Registers | |
89h, 8Ah, 8Bh | Channel 6, 7, 5 DMA Memory Low Page Register |
Reserved Page Registers | |
8Fh | Refresh Low Page Register |
Aliased at | |
(except 92h) |
|
92h | Fast A20 and INIT Register |
continued
Compaq Deskpro EX and Deskpro EXS Series of Personal Computers