Acer Altos G520 series, Service Manual

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18 Chapter 1
0C0-0DF DMA Controller-2, 8237
0F0 CLEAR Math Co-processor BUSY
0F1 RESET Math Co-processor
0F8-0FF Math Co-processor
4A0 System I/O Port
Bit 3: Onboard VGA Enable/Disable
1: Disable
0: Enable
Bit 0: Onboard LAN 1 Enable/Disable
Bit 1: Onboard LAN 2 Enable/Disable
1: Disable
0: Enable
Bit 2: Onboard SCSI Enable/Disable
1: Enable
0: Disable
Bit [4:7]: Host Frequency Setting
[0, 0, 1, 1]: 1/5, reset only
[0, 1, 1, 1]: 2/11, 300 MHz
[1, 0, 0, 0]: 1/6, 350 MHz
[0, 0, 0, 1]: 1/4, 400 MHz
[0, 1, 0, 1]: 2/9, 450 MHz
[0, 0, 1, 1]: 1/5, 500 MHz
4A1 SMISW/SCISW/SOFTNMI
BIOS/Password check control
0CF8 PCI Configuration Address Reg
0CFC PCI Configuration Data Reg
1F0-1F7 Fixed Hard Disk
278-27F Parallel Port 2
2F8-2FF Serial Port 2
378-37F Parallel Port 1
3B0-3BF Monochrome Display
3C0-3CF EGA, VGA, SVGA
3D0-3DF CGA, VGA, SVGA
3F0-3F7 Floppy Disk Controller
3F7-3FF Serial Port 1
Hex Range Device Function
000-01F DMA Controller-1, 8237
020-027 Interrupt Controller-1 8259
030-037 Interrupt Controller-1 8259
IRQ Assignment Map
Interrupt Channel Function
IRQ0 Timer output 0
IRQ1 Keyboard
IRQ2 Reserved
IRQ3 Serial Port 2
IRQ4 Serial Port 1
I/O Address Map
Hex Range Device Function