The parallel interface on the K-class (and earlier models) is quite narrow in it's ability to accomodate the *MANY* versions of the parallel interface, commonly called Centronics. Centronics was the first printer company to define a fairly standard high-speed interface to supplement RS-232 (serial). Large line printers in the 60's and 70's mostly had proprietary interfaces, and it was not until low-cost dot matrix came out that a more portable interface standard emerged.
However, the Centronics interface design varied even within Centronics printers so when the PC market began to drive common (and low-cost) printer interfaces, a lot of attention was paid to integrating smart BIOS and/or electronics to accomodate the differing standards. The standards varied in terms of handshaking and whether these protocol signals were levels or pulsed.
The HP implementation was to control the interface using various minor number values and the man page called "cent" will give the details. There are five separate modes (minor number values) which can all be setup by creating different device files and varying the last hex digit. You can create the device files like this:
mknod /dev/c2t0d0_lp1 c 216 0x020001
mknod /dev/c2t0d0_lp2 c 216 0x020002
mknod /dev/c2t0d0_lp3 c 216 0x020003
mknod /dev/c2t0d0_lp4 c 216 0x020004
mknod /dev/c2t0d0_lp5 c 216 0x020005
Mode 6 is not available for 800 series (K380) boxes. Now try cat'ing a simple file to each device file:
cat /etc/issue > /dev/c2t0d0_lp1
cat /etc/issue > /dev/c2t0d0_lp2
cat /etc/issue > /dev/c2t0d0_lp3
cat /etc/issue > /dev/c2t0d0_lp4
cat /etc/issue > /dev/c2t0d0_lp5
One (or more) of those device files may work. If multiple device files work, use long listings to verify the most reliable handshake mode. NOTE: cat'ing direct to the port will require filtering ASCII files because in Unix, ASCII files are string followed only by a linefeed (LF). For multi-line files, use this:
ux2dos /etc/issue > /dev/c2t0d0_lp1
Note also that cat'ing direct will leave off the formfeed between print jobs, but this is just a test. Once you find a device file that works, add the printer using the dumb model script and you should be ready to print. If none of the files work, you may have one of the few completely incompatible parallel interfaces on your printer. While it may work fine on a PC, even HP's RuggedWriter (a 1980's dot matrix printer) could not be made to work with any HP 9000 server.
In that case, you have an even better solution than parallel: HP makes a Centronics-to-LAN adapter box called a JetDirect External. The 170x is only $129 retail and allows you to move your printer to anywhere you can run a LAN cable. It also allows other machines such as PCs to print to the printer (although you can lockout any incoming jobs based on IPP address). The JetDirect External box has multi-protocol parallel interface capability that is as universal as a typical PC.
Bill Hassell, sysadmin
