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cPCI-MXS64 Technical Reference Manual
NOTE
To operate in EPP or ECP mode, ensure the peripheral is designed to work in
this mode and the BIOS setup is configured to support it.
2.6.1 Standard Mode
The Standard mode is unidirectional. It is supported to maintain the compatibility with the
IBM PC standard.
2.6.2 EPP Mode
The EPP (Enhanced Parallel Port) mode consists of a hardware independent method of
accessing a parallel port configured as EPP. It provides support for single I/O cycle as well
as the high performance block I/O transfers. The EPP mode always uses the most optimum
method for I/O transfers. For example, if the hardware supports it, EPP mode will perform
32-bit I/O block transfers.
EPP mode assumes that the parallel port can be used to connect more than one peripheral
device using multiplexor or daisy chain configurations.
A multiplexor is an external device that permits up to eight parallel port devices to share a
single parallel port.
A daisy chain device has two ports: input and output. The input port is connected either to
the host parallel port or the daisy chain device in front of it. The output is used to connect
the next peripheral device to the daisy chain. The last device, however, can be one without
daisy chain support.
2.6.3 ECP Mode
ECP (Extended Capabilities Port) works the same as EPP mode, but it will take precedence
over the EPP mode when addressing multiple logical devices in a single physical product.
While the EPP mode may intermix read and write operations without any overhead or
protocol handshaking, the ECP mode negotiates data transfers using a request from the host
and an acknowledgment from the peripheral.
2-6
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