Technical information

Check your host documentation to see if the host is 1284 compatible.
Printer-host parallel communication is done in a manner that ensures
compatibility.
This is an advanced version of byte mode which allows transfer of
data in either direction without returning to the compatibility mode.
The parallel communication is a half-duplex channel with either
device, the host or the printer, making a request for data transfer
when there is available data. In the case of simultaneous requests for
transfer, the printer always defers to the host.
Printer-host parallel communication is done via asynchronous bidirec-
tional eight-bit transfer. A return to compatibility mode is not required.
Printer-host parallel communication is done in nibbles (four bits; one-
half byte) with the low order nibble sent first. A transfer of two nibbles
is required for each byte of information.
Your QMS 1725E Print System supports PS Protocol, a new protocol
for communication between the printer and a host computer over the
serial, parallel, and optional interfaces. This binary communications
protocol (BCP) allows any 8-bit binary value (0-255) to be treated as
data, while allowing a few of the values to function as special control
characters. When communicating 8-bit binary data in binary or binary
fixed mode, the printer uses the quoting mechanism of the binary