Q & A on Direct Socket Printing Q: I'm probably off topic and off target as well, but mayby you can help me. I'm familiar with most TCP/IP concepts, including "socket". But i can't seem to find info on "direct socket" I need to know the difference between LPD/LPR and direct-socket-printing. Can you get me on the road? Direct me to an internet-source;, a book ? A: The term "direct socket printing" refers to network-capable printers that maintain their own queues. To use such a device, one creates a socket, uses it to form a TCP connection to the printer, sends a file to be printed, and then closes the connection. The printer contains a CPU, standard TCP/IP protocols, and a storage device (e.g., a disk) for spooling files. The printer maintains a queue of files waiting to be printed, and can accept additional files while it is printing. The lpr/lpd model of printing uses a standard computer running Unix to maintin spooled files and control a printer. To print, one pipes data into the lpr program, which places the data in a file on disk. Once the file has been created, lpr fires off lpd in the background. At most one copy of lpd executes at any time, so if one is already running lpr does nothing. lpd communicates with the printer, sending it one file at a time to print. The advantage of the lpr/lpd model is that software on the computer controls the print queue, priorities, etc. The advantage of the direct socket model is that the printer is self-contained, so one does not need to devote any computer resources to printing.