gardiner@umn-cs.cs.umn.edu (David Gardiner) (05/04/90)
I have a HP Laserjet Series II with a Pacific Page postscript emulation cartridge, hooked up to a 386 (DOS). I want to make the thing print faster and believe that most of the print time is in transmission. I read somewhere that the data transmission to the printer would be better if I used a serial connection than with the current parallel one. Even though the parallel interface transmits more bits per cycle, the serial can run at a much higher cycle rate. Does anyone know if this is true? I think (my manauals are at home) that serial can transmit at 9600 baud. What is the speed of a parallel port? Thanks in advance. David Gardiner P.S. If anyone wants a review of the Pacific Page, let me know. -- -------------------------------------------------------------------- David Gardiner University of Minnesota Computer Science Dept. gardiner@umn-cs.cs.umn.edu
pnl@hpfinote.HP.COM (Peter Lim) (05/06/90)
> I have a HP Laserjet Series II with a Pacific Page postscript emulation > cartridge, hooked up to a 386 (DOS). I want to make the thing print > faster and believe that most of the print time is in transmission. > If you print a lot of bit-mapped graphics then this would be true. Otherwise, Postscript (vector based) usually transmit a lot less code compared to PCL (bit-mapped). Of course, the faster you can transfer the merrier. > I read somewhere that the data transmission to the printer would be > better if I used a serial connection than with the current parallel > one. Even though the parallel interface transmits more bits per > cycle, the serial can run at a much higher cycle rate. > > Does anyone know if this is true? I think (my manauals are at home) that > serial can transmit at 9600 baud. What is the speed of a parallel port? > Don't know about serial being faster than parallel. For a 9600 baud serial transfer to be faster than a parallel port, the parallel port has to transfer at less than 9600 / 8 = 1200 times/second. Which means about under a millisecond per transfer. I don't know how slow the PC's parallel port is, I do remember building a parallel transfer system a long time ago and the rate was like 35 K (Byte or Bit, I can't quite remember) per second. That was a polling system (not even interrupt driven !). Assuming it is 35K bit/second, it is still about 4 times the speed of a 9600 baud serial transfer. So there ..... Of course I could be wrong :-). On a different note; I do have second hand information that the slowness is due to the Pacific Page postscript emulator (PPPE). A friend of mine once tried the PPPE on a LaserJet IID (I believe this is faster than the series II); the thing was hooked on to a UNIX machine. He dumped a short but recursive postscript file (to print a recursive triangle/pyramid type of pattern), it took about 5 minutes. I tried the same file on a 386-25 no cache, with 80387 and Ultrascript (a postscript interpretor). The printer is the lowly LaserJet IIP (the half-speed low cost printer) using parallel port. The page came out at under 2 minutes ! Sure is a lot faster than PPPE on a faster printer ! Of course I have lots of RAM and gave Ultrascript about 3 MB of extended memory to play with. One thing though, when Ultrasript process the postscript file, everything stops on the 386 :-). Regards, ## Life is fast enough as it is ........ Peter Lim. ## .... DON'T PUSH IT !! >>>-------, ########################################### : E-mail: plim@hpsgwg.HP.COM Snail-mail: Hewlett Packard Singapore, : Tel: (065)-279-2289 (ICDS, ICS) | Telnet: 520-2289 1150 Depot Road, __\@/__ ... also at: pnl@hpfipnl.HP.COM Singapore 0410. SPLAT !