Abstract: An improved printer is provided which includes a print engine control program that minimizes the power consumption of the paper-handling devices to allow for a smaller DC power supply. Some of the paper-handling devices are input paper trays, output paper stackers, and a duplexer, which all preferably contain a microcontroller and an individual electric motor drive. The base printer also contains a microcontroller in the print engine that controls the printer's mechanisms and various subassemblies that are used in the laser electrophotographic printing process. To maintain control of the entire paper path, the print engine sends commands to the paper-handling devices, and these devices send responses to these commands. Most of the printer's paper-handling devices receive their electrical power entirely from the base printer, which is supplied as a DC voltage. The print engine avoids the concurrent running of subsystems in cases where the functionality of the printer is not compromised.

Abstract: An improved communications buffer system is provided which dynamically allocates the size and number of buffers to optimally receive and transmit packets of communications data over a communications link, while efficiently using the amount of available memory so as to provide optimal throughput capability with respect to the allocated amount of memory. The printer first determines how much "free" memory is available in its "pool area" and then how best to divide up that pool area into both transmit and receive buffers for a single port. Once the entire pool area has been allocated for these transmit and receive buffers, the communication session can begin between the host computer and the printer for communicating the actual print job data.

Abstract: An improved non-stop, constant velocity laser printer is provided which operates in parallel to both begin printing a particular page of print media while virtually simultaneously receiving further data for that same page from a host computer. Since the communications link between the host computer and the printer is slower than the rate of consumption by the printhead provided with this printer, a certain amount of data for each page is first buffered in the printer before the print media begins to move via the printer's print engine. Since it is important for the printer to receive all of the required data for the entire page before the printhead requires that data for consumption, the printer must decide how much data of that particular page should be buffered within the printer before commanding the print engine to start moving the print media.

Abstract: An improved printing system is provided having at least one host computer and a printer in which the printer acquires print job accounting information and communicates it to the host computer via NPAP messages. A host computer downloads print job data to the printer through a communications port on the printer (i.e., either a parallel port, serial port, or network port), and as the printer prints the print job that it received from the host computer, the printer temporarily stores job accounting information. At the end of the print job, the printer communicates that job accounting information back to armed host computers via a bi-directional communications port, including typical information such as: the job identifier number, job processing time, number of sheets of paper from each paper source, number of impressions from each paper source (either one-sided or two-sided impressions), the port identifier, the network user name, the name of the print job (as specified), and the printer's serial number.