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13. APPENDIX 2. BIDIRECTIONAL PARALLEL INTERFACE

13.1 Overview

The interface of the printer is a Level-1 compatible device according to IEEE-P1284.
It supports the communication modes described in 13.1.1 below.

13.1.1 Parallel Interface Communication Modes

The parallel interface of the printer provides three communication modes as
outlined below. When the printer is turned on or reset, it defaults to Compatibility
mode.
• Compatibility Mode
Data is transmitted from the host to the printer in units of one byte. Usually, this
mode is used for data transmission. You may switch to the other modes from
Compatibility mode.
• Nibble Mode
Data is transmitted from the printer to the host in units of four bits. The data
transmission from the printer uses a status signal line. To send one byte of data
in this mode, two sets of four-bit data are sent consecutively.
• Byte Mode
Data is transmitted from the printer to the host in units of one byte. Data
transmission from the printer uses an 8-bit data signal line. For Byte mode, the
host must be capable of toggling the signal direction over the 8-bit data signal
line. Communication from the host to the printer is called Forward mode, while
communication from the printer to the host is called Reverse mode.