Interfaces, The parallel interface, Signals description – Compuprint 3046 Programmer Manual User Manual
Page 20
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This appendix provides technical information for the parallel and serial interfaces
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The parallel interface of this printer fully supports the Centronics protocol plus the specific features
requested by the EPSON and IBM printer connection in monodirectional mode and the Compatibility
and Nibbles modes in bidirectional mode, plus the negotiation phases and the device identifier (as IEEE
P1284).
The parallel interface is available on a specific 36 contact connector type AMPHENOL
57-40360-12-D56 or equivalent connector for 1284 Type B.
• Drive Capability
Up to 15 feet (5 m) on AWG26 min. wire size of twisted conductors on TTL receiver. The max.
reachable distance is conditioned by the host drive capability and by the noise level along the
interface cable path.
• Printer Connector Type
36 pins, 1284 Type B
• Cable Connector
25 pin, 1284 A Type
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According to the IEEE - P1284 Standard, the pins assume different meanings and are identified by
different names depending on the actual handshaking mode as follows:
• Compatibility mode (Centronics)
This is the lower level mode provides an asynchronous, byte-wide forward (host-to-peripheral)
channel with data and status lines used according to their original definitions. The interfaces power
up in the compatibility Mode Idle phase.
• Nibble Mode
This mode provides an asynchronous, reverse (peripheral-to-host) channel, under control of the
host. In this mode, peripheral device to host data bytes are sent as two sequential, four-bit nibbles
using the four peripheral-to-host status lines. These two modes cannot be active simultaneously.
• Byte Mode
This mode provides an asynchronous, byte-wide reverse (peripheral-to host) channel based on
eight data lines of the interface for data and the control/status lines for handshaking. Byte mode is
under host control and it cannot be simultaneously active with compatibility mode.