QMS 1060, User Manual

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Parallel
Interface Modes
QMS 1060 Print System Reference 5-30
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.
When byte transfer is complete and there is no more data to transmit
the host may do one of the following:
n
terminate and return to the compatibility mode.
n
stay in the HostBusy, Data Not Available phase.
n
set HostBusy Low, putting the interface in the idle phase.
If there is additional data, the host may do one of the following:
n
set HostBusy Low, indicating that the host can accept additional
data.
n
stay in the HostBusy, 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.
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.