Tyan Computer GX21 Switch User Manual


 
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EPP Mode Select
There are two versions of the EPP transfer protocol - EPP 1.7
and EPP 1.9. This BIOS feature allows you to select the ver-
sion of EPP that the parallel port should use.
Generally, EPP 1.9 is the preferred setting because it sup-
ports the newer EPP 1.9 devices and most EPP 1.7 devices;
and offers advantages like support for longer cables. How-
ever, because certain EPP 1.7 devices cannot work properly
with an EPP 1.9 port, this BIOS feature was implemented to
allow you to set the EPP mode to EPP 1.7 when such an
issue ocurrs.
Therefore, it is recommended that you set this BIOS feature
to EPP 1.9. But if you have trouble connecting to your parallel
port device, switch to EPP 1.7. The choices are:
EPP1.9 / EPP1.7
ECP Mode Use DMA
This BIOS feature determines which DMA channel the paral-
lel port should use when it is in ECP mode.
The ECP mode uses the DMA protocol to achieve data trans-
fer rates of up to 2.5 Mbits/s and provides symmetric bidirec-
tional 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. The choices are:
DMA1 / DMA3