Chapter 3 Hardware Description
AI5TT Pentium Baby AT Motherboard User
’
s Manual
9
3.6 DMA Channels
There are seven DMA Channels available on the motherboard. Only
DRQ2 is used by the floppy controller. In the case that ECP mode on the
parallel port is used, DRQ1 or DRQ3 will be used.
3.7 I/O Port Address Map
Each peripheral device in the system is assigned a set of I/O port
addresses which also becomes the identity of the device. There is a total
of 1K port address space available. The following table lists the I/O port
addresses used on the motherboard.
Address
Device Description
000h - 01Fh
DMA Controller #1
020h - 03Fh
Interrupt Controller #1
040h - 05Fh
Timer
060h - 06Fh
Keyboard Controller
070h - 07Fh
Real Time Clock, NMI
080h - 09Fh
DMA Page Register
0A0h - 0BFh
Interrupt Controller #2
0C0h - 0DFh
DMA Controller #2
0F0h
Clear Math Coprocessor Busy Signal
0F1h
Reset Math Coprocessor
1F0h - 1F7h
IDE Interface
278 - 27F
Parallel Port #2(LPT2)
2F8h - 2FFh
Serial Port #2(COM2)
2B0 - 2DF
Graphics adapter Controller
378h - 3FFh
Parallel Port #1(LPT1)
360 - 36F
Network Ports
3B0 - 3BF
Monochrome & Printer adapter
3C0 - 3CF
EGA adapter
3D0 - 3DF
CGA adapter
3F0h - 3F7h
Floppy Disk Controller
3F8h - 3FFh
Serial Port #1(COM1)
