Citizen Systems iDP3240 user manual Bidirectional Parallel Interface IEEE1284, Outline

6.PARALLEL INTERFACE

6.1Bidirectional Parallel Interface (IEEE1284)

6.1.1Compatibility Mode (Host → Printer communication :

Centronics compliant)

•General description

This printer provides Compatibility Mode, which specifies the Centronics interface conventionally used for a wide variety of applications.

•Specifications

Data transfer method:	8-bit parallel
Synchronizing method:	Controlled by nStrobe signal externally supplied
Handshaking:	Handled by nAck and Busy signals
Signal level:	All signals are C-MOS compatible

6.1.2 Reverse Mode (Printer → Host communication)

Data transfer from the printer to the host computer is conducted in Nibble or Byte Mode. (For details, See “APPENDIX 2. BIDIRECTIONAL PARALLEL INTERFACE”.)

Outline

The reverse mode has been devised to handle data transfer from an asynchronous printer controlled by a host computer.

In Nibble Mode, data is transferred, 4-bits (A nibble) at a time, using traditional control lines. In Byte Mode, data is transferred by making 8-bit data lines bi- directional. Note that either mode cannot work simultaneously with Compatibility Mode, thus resulting in half-duplex transmission. (For details, See “APPENDIX 2. BIDIRECTIONAL PARALLEL INTERFACE”.)

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