HP 5100tn Printer Job Language - Technical Reference Manual - Page 200

Example Printing System Figure 10-1 contains an example printing system. The print system contains one I/O-switching LaserJet printer which is connected to seven computers. Host computer #1 is connected via the serial I/O interface. Host computers #2 and #3 are connected through an external printer sharing box that also buffers print job data. The printer sharing box is connected to the printer through the Bi-Tronics I/O interface. Network servers #4 and #5 spool print jobs from network clients #6 and #7. Although all the network clients and spoolers are connected to the same network cable as the printer, only the two network servers are capable of communicating directly with the printer. In this example, the network clients spool print jobs to a network server; they can not interact directly with the printer. Given the printing system as shown in Figure 10-1, not all of the printing system components can query the printer and expect a response back. Printer Status Readback and Printer Sharing Host computer #1 is directly connected to the printer via the bi-directional serial I/O link. If the software on the host computer supports bi-directional printer communication, applications on host computer #1 can expect the printer to respond to queries. However, at the time an application on host computer #1 requests information, the printer may be processing a print job from a different I/O interface, so the response to host computer #1's query may be delayed, as described in the "Printer Status Readback and Printer I/O Switching" section in this chapter. 10-20 Programming Tips