TYAN Tempest i5400XL User Manual page 57

This field allows the user to select the parallel port mode.
In addition to "Output only" and "Bi-directional", there are two faster bidirectional
modes available - the ECP (Extended Capabilities Port) and EPP (Enhanced
Parallel Port) modes.
ECP uses the DMA protocol to achieve data transfer rates of up to 2.5 Mb/s and
provides symmetric bidirectional communication. On the other hand, EPP uses
existing parallel port signals to provide asymmetric bidirectional communication.
Generally, because of its FIFOs and the DMA channel it uses, ECP is good for
large data transfers (useful for scanners and printers). On the other hand, EPP is
better with links that switch directions frequently (like parallel port drives).
Output only / Bi-directional / EPP / ECP
Base I/O Address
Set the base I/O address for parallel port.
378 / 278 / 3BC
Interrupt
Set the interrupt for parallel port
IRQ7 / IRQ5
DMA Channel
This BIOS feature determines which DMA channel the parallel port should use
when it is in ECP mode.
The ECP mode uses the DMA protocol to achieve data transfer rates of up to 2.5
Mbits/s and provides symmetric bidirectional communications. For all this, it
requires the use of a DMA channel.
By default, the parallel port uses DMA Channel 3 when it is in ECP mode. This
works fine in most situations.
This feature is provided just in case one of your add-on cards requires the use of
DMA Channel 3. In such a case, you can use this BIOS feature to force the parallel
port to use the alternate DMA Channel 1.
Please note that there is no performance advantage in choosing DMA Channel 3
over DMA Channel 1 or vice versa. As long as either Channel 3 or Channel 1 is
available for your parallel port to use, the parallel port will be able to function
properly in ECP mode.
DMA 1 / DMA 3
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