Communications
PcOS Series 90PLUS
Programmer's Guide
Overview
Page 130
Rev Q
11/07/05
The print control software takes information from the buffer (as it needs it and can use it). When the buffer
output function finds that the buffer is getting low, it notifies the communication driver that the information flow
can be resumed (if it was stopped) and allows more information to be placed in the buffer.
The Series 90PLUS Printer has a configurable input buffer. The printer can be configured to allow from 256 to
6144 bytes of input. This means that up to 6144 characters (or control codes) can be sent to the printer before
they are interpreted and printed. In effect, the host computer can get 6144 characters ahead of the printer. In all
cases, the buffer will resume communications when it is half empty. For example, if the buffer is configured to
be 2K, the printer will signal stop when 2048 bytes are in the buffer; resume will be signaled when 1024 bytes
remain.
Inquire (ENQ) commands are preprocessed, which means they are found in the input data stream and acted upon
as they are received, so the status returned is valid as of the time the command is received. This is termed, “real-
time status” even though inquire commands are preprocessed and still placed in the buffer. Real-time status
assures that data is not lost when the inquire sequence is part of another command. However, this also means
that the buffer may be filled by inquire commands if the printer is waiting for some activity.
Summary of Contents for Ithaca 90PLUS Series
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