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PCI Bus Master Technology
As opposed to PCI cards with PCI target chip, the TRACE PRO AE is
constructed as PCI bus master card. The PCI bus master technology offers
some important advantages: It allows extremely small latencies while
keeping the CPU load very small. Such qualities are fundamental key
functions for a powerful digital audio workstation (DAW). Unfortunately,
the PCI bus master technology also has a disadvantage.
Background
: The principle of operation allows for a PCI card to
independently initiate a data communication with the main board of the
computer. The parameter for the time wise length of such data transfer is
called “PCI Latency Timer”.
Problem
: If this time is very long, a PCI card may perfectly and effectively
exchange data with the main board, but on the other hand, it may block
other components, trying to do the same. That’s why it could happen, that
e.g. a network card or a hard drive controller might hinder the operation of
the TRACE PRO AE, if the PCI Latency Timer for this component is set up
very high.
Solution
: If, even with correct driver- and DMA latency time, digital clicks
or distortions appear on a recording or a playback when using the TRACE
PRO AE with a lot of channels on high samplerates, it may appear
necessary to perform changes at the PCI Latency Timer. Some BIOS
allows changing the PCI Latency Timer for every PCI slot separately. That
means, if you figure out, that e.g. the latency time for the network card of
the computer is set up quite high (64 or more) and thereby hinders the
TRACE PRO AE, the PCI Latency Timer for this component has to be
reduced. Some other BIOS allows only global changes of the PCI Latency
Timer parameter. In that case the time frame may only be changed for all
components equally. But also on the Internet several programs are offered,
that allow adjustments of the PCI Latency Timer for different components
