NetWare 4.1/9000 Print Services

C-3
Optimizing Network Printing Performance
Parallel Versus Serial Ports
Parallel Versus Serial Ports
The primary factor that affects network printing speed is whether you
connect the printers to parallel ports or serial ports. Parallel ports normally
are about two times faster than serial ports at 9,600 baud, and up to four
times faster than serial ports at 4,800 baud. Unless distance requires the use
of a serial port, use the parallel port for best performance.
NPRINTER.EXE software for NetWare Services and RPRINTER for
releases after NetWare 3.11 can send data to a printer's parallel port as fast as
most laser printers can receive it. The current limit is about 35KB per second
and will increase as new versions take advantage of new hardware that is
likely to appear.
Serial ports are essentially limited by the baud rate used. In general, the data
rate in bytes per second will approximate the baud rate divided by ten. At
9600 baud, the maximum data throughput is about 0.96K bytes per second.
NPRINTER.EXE for 4.0 and RPRINTER for releases after NetWare 3.11
support 19.2K baud and 38.4K baud, which yield maximum data
throughputs of about 1.92K bytes and 3.84K bytes per second, respectively.
Estimating Data Transmission Rates
With bit-mapped graphic images, including text output from many word
processing configurations, printer speed may be limited solely by how fast
the data can pass through the workstation's print port to the printer.
Choose an interface that is fast enough to keep up with the bulk of the print
jobs to be run on a particular printer. To do this, you will need to estimate the
data transmission rate for that printer.
• For printers rated in characters-per-second (CPS), use the CPS rating for the
preferred font and point size as the estimated data transmission rate. Assume that
only print engine limitations will limit printer output.
• For page-per-second rated printers, estimate print data transmission this way:
• For a representative print job, count the number of pages to be printed.
• Print the job to a file and record the finished file size in bytes.
• Divide the total pages (pages-per-job) by the pages-per-minute and multiply