UF-490, UF-4000, UF-4100, UF-490YC, UF-490YR - Panasonic Fax Service Manual (repair manual). Page 9

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• 2-4. LP Engine Control Block

•High Voltage Development Clock Control

It generates control pulse signals with a High Voltage Supply.

•LSU Control

It generates control pulse signals and control a LSU Scan Motor such as observing abnormal 
rotation, etc. It also controls Laser output signals for synchronizing horizontal lines.

•Fuser Control

It controls on/off of Fuser heater with a Low Voltage Power Supply.

•IEEE 1284

It proceeds handshaking conforms to IEEE 1284 requirement and transfers data, such as a 
receiving data from PC (Printer Interface) or a transmit scanned data to PC (PC Scanner). 
It is complied with Compatibility Mode, Nibble Mode, Byte Mode, ECP Mode.

3. System Memory

This system consists of the following memories.

•F-ROM (IC5) 

→ F-ROM (2MB) for programming and data backup.

The program is downloaded from PC via IEEE 1284 parallel port.

•S-DRAM (IC6) 

→ Work RAM, Page Memory, Line Memory, Image Data Memory, Buffer 

(8MB) for transmission and reception. During an electrical power failure, the image data is not 
backed up.