HP LaserJet M1005 Service Manual - Page 62
Formatter system, Central processing unit, Standard boot process, Device startup messages
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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 device interface ● monitoring the control panel and relaying device-status information ● developing and coordinating data placement and timing with the print engine ● communicating with the host computer through the bidirectional interface The formatter receives print data from the universal serial bus (USB) interface in a compressed raster format. The firmware decompresses the raster data and sends the data to the ECU. The ECU initiates the printing processes to transfer the data to the page. Central processing unit The formatter incorporates an embedded Tensilica processor operating at 230 MHz. Standard boot process When the device 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 64K of code). The second block of code is a compressed version of the device control code. When the device is turned on, the boot block decompresses the device control code and stores it in RAM. Then the device performs a full startup with the control code running from RAM. Device startup messages The LCD display contains different messages depending upon the progress of the boot process: Table 5-2 Device startup messages Message -blank- Contact Service Hewlett Packard Ready......... Cause (Blank display for many seconds after power-on.) Boot-block failure. Control-code failure. The device is starting up. Device startup is complete and the device is ready for use. Solution Use the power switch to turn the power to the device off. Check all wire-harness connectors and FFCs to make sure that they are firmly connected. Replace the formatter. See Formatter on page 94. Replace the formatter. See Formatter on page 94. Wait for the Ready message. Begin using the device. 46 Chapter 5 Theory of Operation ENWW