Page: 20Service Guide OL400Chapter 2 Principles of Operation2.3.03 Engine BoardThe Engine Board is composed of the items listed below.MPU80C51, or MPU83C154 (8-bit CPU)LLAB Revision 11The MPU 83C154 contains the printer control program in its internal ROM.Therefore, the external ROM (Q1) is not required on Revision 11.MSM73H019GS (80 pin LSI)EPROM (Printer Control Program)EPROMThis 1-Kbit electrically erasable PROM (EEPROM) is loaded with the following data:Total number of sheets printed after installationTotal number of sheets printed with the current drumTotal number of sheets printed with the current fuserSetting of time required from the completion of printing to Stand-byFeed length needed to feed the paper to a printable position.Print starting line on paper (Top margin)LED head drive time.NOTE:The EEPROM preserves the above data while the supply voltage is off.The count of the total number of sheets printed after installation cannot be reset.The count of the total number of sheets printed with the drum currently in use should betaken as a rough measure of the useful life of the drum.It is reset to zero when the drum is replaced by holding down the RESET button andapplying power to the printer.Copyright 1997, Okidata, Division of OKI America, Inc. All rights reserved. See the OKIDATA BusinessPartner Exchange (BPX) for any updates to this material. (http://bpx.okidata.com)
