Xerox 96 NPS manual Dpi versus 600 dpi performance

ADJUSTING PRINT QUALITY AND SPEED

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

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:

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

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.

XEROX DOCUPRINT 96/4635/180 NPS TROUBLESHOOTING GUIDE 7-9