40
1st MB Memory Address Map
Memory address
Description
00000-9FFFF System
memory
A0000-BFFFF VGA
buffer
C0000-C7FFF VGA
BIOS
F0000-FFFFF System
BIOS
1000000- Extend
BIOS
IRQ Mapping Table
IRQ0 System Timer
IRQ8
RTC clock
IRQ1 Keyboard
IRQ9 Available
IRQ2 Cascade to IRQ Controller IRQ10 COM4
IRQ3 COM2
IRQ11 COM3
IRQ4 COM1
IRQ12 PS/2
mouse
IRQ5 Audio
Device
IRQ13 FPU
IRQ6 FDC
IRQ14 Primary
IDE
IRQ7 Printer
IRQ15 Secondary
IDE
DMA Channel Assignments
Channel Function
0
Available
1
Available
2
Floppy disk (8-bit transfer)
3
Available
4
Cascade for DMA controller 1
5
Available
6
Available
7
Available