Ieee1284 Parallel Interface; Mode - Epson TM L90 Technical Reference Manual

A.2 IEEE1284 Parallel Interface
A.2.1 Mode
The IEEE1284 parallel interface is comprised of the following two modes.

Mode

Compatibility Mode
Reverse Mode
❏ Compatibility Mode
Compatibility Mode is Data Transmission from Host to Printer: Centronics compatible.
Specifications
• Data transmission:8-bit Parallel
• Synchronization:
• Handshaking:
• Signal levels:
• Connector:
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.
A-4 Interface And Connectors
Communication direction
Host → printer
communication
Printer → host
communication
Externally supplied n*Strobe signals
n*Ack and Busy signals
TTL compatible
ADS-B36BLFDR176 (HONDA) or
Other information
Centronics standard
Assumes a data transfer from an asynchronous printer.
Rev. B