jbn@glacier.STANFORD.EDU (John B. Nagle) (09/11/88)
I'm losing characters between my PC and Laserwriter. I assume that I have flow control problems. The present setup is: PC is running the standard DOS 3.1 PRINT program and driver. The cable connection between the PC and the Laserwriter has a null modem box from 3M, with TX1 -> RX2 DTR1 -> DSR2 CTS1 -> RTS1, DCD2 TX2 -> RX1 DTR2 -> DSR1 CTS2 -> RTS2, DCD1 3M calls this a "standard null modem". It seems strange, in that flow control is normally provided via RTS/CTS. Yet the Laserwriter documentation indicates that the Laserwriter tries to do flow control on DSR/DTR, which is nonstandard. The Laserwriter (a IINT) is in DSR/DTR mode, 9600 baud. Postscript files (which are not missing characters) sent to the printer lose 1 to 10 characters on rare occasions, perhaps once every few pages. What are the PC printer conventions on flow control, anyway? Where is this documented? John Nagle
gts@violet.berkeley.edu (Greg Small) (09/12/88)
= From: jbn@glacier.STANFORD.EDU (John B. Nagle)
= The Laserwriter (a IINT) is in DSR/DTR mode, 9600 baud.
= It seems strange, in that flow control is normally provided via RTS/CTS.
= Yet the Laserwriter documentation indicates that the Laserwriter tries
= to do flow control on DSR/DTR, which is nonstandard.
Actually, DTR/DSR is far more common for flow control than RTS/CTS and neither
were specified for that function (RTS/CTS was for half-duplex line turnaround).
Look in the back of the LaserWriter NT manual under printing on MS-DOS. It gives
the PostScript program to be sent to the LW that sets DTR/DSR flow control.
What they do not mention is that the file must be terminated with Ctrl-D.
Just copy the file to the LW serial port.
statusdict begin 25 sccbatch exch pop
4 eq {stop} if
serverdict begin 0 exitserver
statusdict begin 25 9600 4 setsccbatch
Ctrl-D
This also should work for an old LaswerWriter Plus but not the plain LW.
Gregory T Small (415)642-5979
Personal Computer Networking & Communications gts@violet.Berkeley.EDU
Workstation Support Services - Software Group ucbvax!jade!gts
267 Evans Hall SPGGTS@UCBCMSA.BITNET
University of California, Berkeley, Ca 94720cramer@optilink.UUCP (Clayton Cramer) (09/13/88)
In article <14151@agate.BERKELEY.EDU>, gts@violet.berkeley.edu (Greg Small) writes: > Look in the back of the LaserWriter NT manual under printing on MS-DOS. It gives > the PostScript program to be sent to the LW that sets DTR/DSR flow control. > What they do not mention is that the file must be terminated with Ctrl-D. > Just copy the file to the LW serial port. > > statusdict begin 25 sccbatch exch pop > 4 eq {stop} if > serverdict begin 0 exitserver > statusdict begin 25 9600 4 setsccbatch > Ctrl-D > > This also should work for an old LaswerWriter Plus but not the plain LW. Not quite. Early Apple LasrWriters had a release of PostScript (V17.0, if my memory serves me right) that didn't have provision for supporting DTR protocol. At some point, LaserWriters started coming with the newer version (V23.0?) that did support DTR as well. Clayton E. Cramer