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ADJUSTING PRINT QUALITY AND SPEED
XEROX DOCUPRINT 96/4635/180 NPS TROUBLESHOOTING GUIDE 7-9
In the example shown in this log, here is the calculation:
The start time was: 4:09:08 pm
The stop time was: 10:23:31 pm
(This gives an elapsed time of 16 minutes and 30 seconds, or
990 seconds)
PPM = 60 x 2170/990 = 131.5 pages per minute
As you can see for the same job, the calculated throughput
approaches the maximum speed of the printer as the start-up latency
becomes less important and the calculation is closer to the actual
sustained throughput of the job.
300 dpi versus 600 dpi performance
There is one additional issue to consider when running performance
tests with the Model 96, 4635, or 180 systems. The above examples
were run at 300 spots per inch resolution. When a block of jobs starts,
the DocuPrint will report the printing resolution, the page size of the
document, and the number of page buffers available in the software
for the job. At 300 dpi, on 216 x 279 mm paper (UsLetter), 139 page
buffers are reported allocated. This is consistent with a DocuPrint
Printer Controller with 192 MB of memory installed.
When running jobs at 600 dpi, the amount of available page buffers
available is 4 times smaller. This leads to a corresponding decrease
in the overall performance of a job. Here is the sequencer log entry
when the above job is run at 600 dpi:
As shown above, only 35 page buffers are allocated at 600 dpi. The
decomposition rate of this job at 600 dpi is:
PPM = 60 x 217/147.92 = 88.0 pages per minute,
which represents the maximum rate that this job can be printed at
600 dpi.
Job #245 start, ftpadmin, 99995163.ps, November 19, 1996 4:06:34 pm PST
Job #244 stop, ftpadmin, 99995163.ps, November 19, 1996 4:07:31 pm PST
pages: 217, decomp: 90.09, elapsed: 154.39, compress: 4.39x, min free:
101877K
compress pages: 13, expand pages: 0
Job #245 stop, ftpadmin, 99995163.ps, November 19, 1996 4:09:08 pm PST
pages: 217, decomp: 87.61, elapsed: 154.50, compress: 5.48x, min free:
101893K
compress pages: 7, expand pages: 0
Job #214 start, ftpadmin, 99995163.ps, November 19, 1996 1:10:37 pm PST
Printing duplex, 600 spi, 216 x 279 mm, 35 buf
Job #214 stop, ftpadmin, 99995163.ps, November 19, 1996 1:13:38 pm PST
pages: 217, decomp: 147.92, elapsed: 181.47, compress: 15.08x, min
free: 101670K
compress pages: 5, expand pages: 0