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Service Guide OL400
Chapter 2 Principles of Operation
2.3.03 Engine Board
The Engine Board is composed of the items listed below.
MPU80C51, or MPU83C154 (8-bit CPU)
LLAB Revision 11
The 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)
EPROM
This 1-Kbit electrically erasable PROM (EEPROM) is loaded with the following data:
Total number of sheets printed after installation
Total number of sheets printed with the current drum
Total number of sheets printed with the current fuser
Setting of time required from the completion of printing to Stand-by
Feed 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 be
taken 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 and
applying power to the printer.
Copyright 1997, Okidata, Division of OKI America, Inc. All rights reserved. See the OKIDATA Business
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