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Parallel Interface
Interface Signal Path
This printer uses a high-speed parallel interface to accept data transfers at
rates up to 300,000 characters per second.
The interface board contains the circuitry needed for CENTRONICS parallel
and Dataproducts short line parallel interfaces. The Dataproducts interface
requires an optional internal cable with the proper connector.
The optional Dataproducts long line parallel interface requires an additional
circuit board as well as the internal cable with the proper external connector.
This long line interface is used for installations where the printer may be
located up to 500 feet (152 meters) from the host.
All parallel interfaces accept seven- or eight-bit data transfers.
Input Buff er Size
Two 4090-byte buffers are provided to store data when using the parallel
interface. When one buffer is full, incoming data is switched to the second
buffer. When using the multisource interface option, buffer size is reduced to
2045-byte. This allows both the parallel and serial interfaces to have two
2045-byte storage areas.
CENTRONICS Interface Operation
4-2
u~r·s
Manual
The data source can clear the input buff er through the PRIME lead before
initiating a data transfer. Selection of the printer for receiving data will cause
the SELECT line to go high, identifying the printer
to
the data source as
being available to print received data.
Data is applied to the printer on eight parallel lines on specific pins at the
interface reserved for this purpose. Each eight bits placed on the parallel
input data bus is strobed into a latch by the STB pulse. Thereafter, the
printer moves the data into a buffer for subsequent printing by means of a
direct memory access routine.
The printer accepts the data and control signals from the data source.
Printer status is furnished to the host through the data cable via the
interface logic board.
Nov 93
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