HP qms 1660 Manuale Utente
Parallel
Interface Modes
5-31
Additional Technical Information
Byte Mode
Printer-host communication is done in bytes.The byte mode may be
used by the host device in a DMA (Direct Memory Access) mode for
more efficient operation.
used by the host device in a DMA (Direct Memory Access) mode for
more efficient operation.
When byte transfer is complete and there is no more data to transmit,
the host may do one of the following:
the host may do one of the following:
n
Terminate and return to the compatibility mode.
n
Stay in the Host Busy, Data Not Available phase.
n
Set Host Busy Low, putting the interface into the idle phase.
If there is additional data, the host may do one of the following:
n
Set Host Busy Low, indicating that the host can accept additional
data.
data.
n
Stay in the Host Busy, Data Not Available phase.
n
Terminate and return to the compatibility mode.
Check your host documentation to see if the host is 1284 compatible.
Compatibility Mode
Printer-host communication is done in a manner that ensures com-
patibility.
patibility.
ECP (Enhanced Compatibility Port) Mode
This is an advanced version of byte mode which allows transfer of
data in either direction without returning to the compatibility mode.
The communication is a half-duplex channel with either device, the
host or the printer, making a request for data transfer when there is
available data. In the case of simultaneous requests for transfer, the
printer always defers to the host.
data in either direction without returning to the compatibility mode.
The communication is a half-duplex channel with either device, the
host or the printer, making a request for data transfer when there is
available data. In the case of simultaneous requests for transfer, the
printer always defers to the host.