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Performance Considerations
The printer prints letter size and A4 size fanfold paper at 27 pages
per minute portrait (one page every 2.2 seconds) and 35 pages per
minute landscape. To sustain printing at full speed, data for each
page must be received and rendered in less than 2.2 seconds for
portrait mode (otherwise the printer will pause).
Failure to print at full speed may be caused by one or more of the
following:
•
an inefficient application program
•
an insufficient communication interface bandwidth
•
a slow host computer
•
a low priority on the host printer port or printing task
•
a highly complex print job, usually containing a large number of
characters and graphics that exceeds the bandwidth of the
controller
An inefficient application program is listed first because a highly
efficient program sends fewer characters to the printer than a less
effective program, and it can be used to overcome the other four
causes of performance problems. This is especially true of IGP/
VGL and IGP/PGL applications, due to the power of these printer
emulations. In many cases, converting a program from IGP/VGL to
IGP/PGL results in substantial performance improvements.
Wide width printing jobs with a large number of characters on a
page can exceed the communication bandwidth and/or the
communication speed of the host computer. A plain text print job of
132 columns by 66 lines requires a sustained data transmission
rate of 3485 characters per second, or for serial communication a
sustained throughput of 34.85 KBaud (assuming 8 bits of data, 1
stop bit, 1 start bit, and no parity bit). In this case, RS-232 would not
be an acceptable selection for communication because the
maximum RS-232 baud rate of 19.2 KBaud is less than the
required 34.85 KBaud sustained throughput. Sustaining high
communication data transfer rates may require the host computer
to be tuned to meet the printer's speed requirements.
Performance Considerations
247
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