dbfunk@ICAEN.UIOWA.EDU (David B Funk) (05/24/89)
A reader saw my LaserJet posting and asked me a question: > I read your nice article on Laserjet printers and have a couple > of questions. Are you connecting your printer through the > parallel or serial port? I really want to know if you have a > printer driver for a Laserjet hooked up to a parallel port on > one of those SPE boards. I can see how that would be a lot > faster. I originally wrote my driver only for serial I/O, but after we got some SPE boards, I tried a parallel I/O version. After doing some tests, I dropped it because it was slower than the serial version and took a lot more CPU time. The details: Node type: DN3000, OS: sr9.7.0.4, SPE v1.3. Bitmap size 1024 X 800 (cpscr on a 19L monochrome display) at 100 DPI Print time: SIO 9600 baud: 108 seconds SPE parallel: 88 seconds SIO 19200 baud: 55 seconds It looks like the SPE parallel driver does not use interrups, it uses only polled I/O. If you take the printer off-line during a print job, the print-server goes in a spin loop and takes up 60% of CPU time. If you use SIO with hardware handshake, when you take the printer off-line the print-server just stops and waits. So for my money, the serial port at 19200 baud is the way to go. Dave Funk