HP 3015 Service Manual - Page 93
Formatter system, Central processing unit, Line interface unit (HP LaserJet 3015 and 3030 only) - laserjet firmware
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Formatter system The formatter coordinates the major systems. It is responsible for the following tasks or actions: ● formatting and controlling copies ● receiving and processing print data from the printer interface ● monitoring the control panel and relaying printer-status information ● developing and coordinating data placement and timing with the print engine ● communicating with the host computer through the bidirectional interface ● communicating fax data to and from the LIU (HP LaserJet 3015 and 3030 only) The formatter receives print data from the bidirectional enhanced capabilities port (ECP) mode interface or universal serial bus (USB) interface and converts it into a dot image. The ECU synchronizes the image-formation system with the paper-feed system and signals the formatter to send the print-image data. The formatter sends the print-image data (dots) in the form of a video signal, and the printing process begins. Central processing unit The formatter incorporates an embedded Coldfire V4 processor operating at 133 MHz. Line interface unit (HP LaserJet 3015 and 3030 only) The line interface unit (LIU) provides the required safety isolation, signal coupling, and impedance matching between the telephone line and the modem chipset that is located on the formatter. Standard boot process When the product is unplugged or the power is off, the firmware code is stored on the formatter in two blocks. The first block of code is an executable boot block (about 64 K of code). The second block of code is a compressed version of the product control code. When the product is turned on, the boot block decompresses the product control code and stores it in RAM. Then the product performs a full startup with the control code running from RAM. Product startup messages The LED display contains different messages depending upon the progress of the boot process: ENWW Formatter system 75