Xerox WorkCentre Pro 412 Service Manual page 37

5-2-4 Program ROM (Flash Memory) Control
1) Device
Type No.
Capacity
2) Programming
Before assembly
After assembly
3) Operating Principle
When the RCSO(ROM CHIP SELECT) signal is activated from the CPU after the POWER is ON, it activates
RD SIGNAL and reads the DATA(HIGH/LOW) stored in the FLASH MEMORY to control the overall system.
The FLASH MEMORY may also write. When turning the power on, press and hold the key (power switch) for
2 - 3 seconds, then the LED will scroll and the PROGRAM DOWNLOAD MODE will be activated. In this
mode, you can download the program through the parallel port.
Tr Ta
MCLK
nWR
A23-2
ROMCS
nTA
WorkCentre Pro 412
Launch Issue
AM29F800B
4 Mbyte (512K * 16BITS * 4)
EPROM programmer or programming at the factory
Download from PC
Tw Tw Tw Tw
ACC+1
SETUP
Write Timing Diagram for Two Beat Burst Cycle
August 2001
Tw Tw Tw Td
HOLD
Circuit Description
Tr Tr Tr Tr
5-11