A-4 Interface And Connectors Rev. B
A.2 IEEE1284 Parallel Interface

A.2.1 Mode

The IEEE1284 parallel interface is comprised of the following two modes.
Compatibility Mode
Compatibility Mode is Data Transmission from Host to Printer: Centronics compatible.
Specifications
Data transmission:8-bit Parallel
Synchronization: Externally supplied n*Strobe signals
Handshaking: n*Ack and Busy signals
Signal levels: TTL compatible
Connector: ADS-B36BLFDR176 (HONDA) or
equivalent (IEEE 1284 Type B)
Reverse communication (Printer Host):Nibble or Byte Mode
* n before the signal name indicates active LOW.
Reverse Mode
The status data transmission from the printer to the host proceeds in the Nibble or Byte mode.
This mode allows data transmission from the asynchronous printer under the control of the
host.
Data transmissions in the Nibble Mode are made via the existing control lines in units of four
bits (Nibble). In the Byte Mode, data transmissions proceed by making the eight-bits data lines
bidirectional.
Both modes fail to proceed concurrently with the Compatibility Mode, thereby causing half
duplex transmission.
Mode Communication direction Other information
Compatibility Mode Host printer
communication
Centronics standard
Reverse Mode Printer host
communication
Assumes a data transfer from an asynchronous printer.