Aaeon SBC-555 Manual page 54

IDE Primary Master/Slave PIO
These four lines set the hard disk PIO transfer mode, which affects
the hard disk data transfer rate. The system will auto-detect the
PIO mode of a device in any of these positions when they are set
to 'Auto', the recommended setting. Alternatively, you can set the
mode manually. Modes 0 to 4 are supported.
Primary Master/Slave UltraDMA
These four lines enable hard disk UltraDMA transfer mode, which
requires a drive that supports this data transfer method. The
system will auto-detect an UltraDMA device in any of these four
positions when they are set to 'Auto', the recommended setting.
The other setting is 'Disabled". You can leave these set to Auto
without effect if there are no UltraDMA devices installed
IDE Burst Mode
When this item is Enabled, the system will support burst data
transfer mode to increase HDD transfer speed.
IDE Data Port Post Write
This item allows users to select Enabled to use data port post write
for IDE drive.
IDE HDD Block Mode
Set this item to Enable to use HDD block transfer mode.
Onboard FDD Controller
Enables or Disables the onboard Floppy Druve controllers.
Onboard Serial Port 1/2
Sets the I/O address for serial ports 1/2. The system will auto-
detect the COM port address when this item set Auto, the default
setting.
COM1/3F8 (Default of onboard serial port)
COM2/2F8 (Default of onboard serial port)
COM3/3E8
COM4/2E8